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VEGETATION

OF THE

PEAK DISTRICT

CAMBKIDGE UNIVERSITY PRESS
ILonion: FETTEB LANE, B.C.
C. F. CLAY, MANAGER

100, PRINCES STREET
ILonHon: WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND
Berlin: A. ASHER AND CO. *
Eetpjifl: F. A. BROCKHAUS
#efo!orfc: G. P. PUTNAM'S SONS
ana Calcutta: MACMILLAN AND CO., LTD.

VEGETATION

OF THE

PEAK DISTRICT

C. Ef MOSS

B.A. (Cantab.), D.Sc. (Viet.), F.R.G.S., F.L.S.,
Curator of the Herbarium, University of Cambridge

Cambridge :
at the University Press

(JTambrtoge :

PRINTED BY JOHN CLAY, M.A.
AT THE UNIVERSITY PRESS

?«imto IN CHEAT

PREFACE

study of vegetation in the British Isles, begun by the
J- late Robert Smith, is being vigorously prosecuted by the
members of the British Vegetation Committee. Already,
several vegetation maps and memoirs have been published of
parts of the central and northern Pennines, Scotland, Ireland, and
Somerset by W. G. Smith, Lewis, Pethybridge, Praeger, Rankin,
and myself, in addition to several minor publications by these
and other members. Whilst this book was going through the
press, Tansley's Types, of British Vegetation appeared, where,
for the first time, a sketch of the plant formations and plant
associations of the whole of the British Isles is given. Several
vegetation maps, of Hampshire, the Isle of Wight, Norfolk,
north-eastern Yorkshire, Lanarkshire, and other districts, have
been finished by various members of the Vegetation Committee,
but cannot be published at present owing to lack of funds.
The present volume and the accompanying maps owe their
publication to the generosity of the Royal Society and the
Royal Geographical Society, whom I take the present oppor-
tunity of thanking on my own behalf and on that of British
phytogeographers and ecologists in general. I fear, however,
that, until government recognition is taken of the botanical
survey of the country, publication of this kind of work will
continue to languish.

The present work is the result of a botanical survey of the
Peak District of the southern Pennines begun in January, 1903.
In preparing the vegetation maps, the Ordnance maps on the
scale of six inches to the mile (1 : 10560) were used for field
work. However, these were not found so superior to ' the

vi PREFACE

one-inch maps as had been anticipated, owing to the fact that
the six-inch maps of the moorlands of the district, with the
exception of those in the West Riding of Yorkshire, are not
contoured.

With regard to the nomenclature of plant communities, the
terms plant formation and plant association are used in
accordance with resolutions passed unanimously by the British
Vegetation Committee, and presented to the International
Congress of Botanists held at Brussels in 1910. They are
used in the same sense throughout Tansley's Types of British
Vegetation.

The names of plants are, as a rule, the same as those given
in the tenth, the latest edition of The London Catalogue of
British Plants (London, 1908). This being so, the author-
citation is omitted, as being unnecessary in a work of this
character : synonyms, however, are added in special cases. The
sequence adopted is that of Engler's system which, in several
European countries and in the United States of America, is
rapidly superseding that of Bentham and Hooker.

I wish to thank Mr J. Ramsbottom, B.A., of the British
Museum (Natural History), for kindly reading the proof-sheets,
the Royal Geographical Society for use of the blocks of figures
4, 12, 15, 22, 24 and 25, and Mr A. Wilson, F.L.S. for use of the
blocks of figures 19, 30 and 31.

C. E. M.

CAMBRIDGE,

December 1912.

CONTENTS

CHAPTER I

INTRODUCTION

General description of the Peak District. Types of scenery. Rocks and
soils. Soils and their characteristic plants. Flora and vegetation.
Vegetation maps. Plant communities. Vegetation maps and floristic
maps. The value of vegetation maps. Rainfall. Smoke. Tempera-
ture. The upper atmosphere ; temperatures ; direction of the wind ;
velocity of the wind ; humidity of the atmosphere. Note on the use
of the words "acidic" and "basic." pp. 1-37

•\

CHAPTER II

WOODLAND ASSOCIATIONS

Distribution of the woods. Woodland associations of Great Britain.
Woodland associations of the southern Pennines. Factors related to
the distribution of the woodland associations. Oak woods of Quercus
Robur. Transitional woods of Quercus Robur and Q. sessiliftora.
Oak woods of Quercus sessiliflora ; trees and shrubs ; variation of
vegetation in the oak woods ; influence of shade on the ground vege-
tation. Alder-willow thickets. Birch woods of Betula pubescent ; the
primitive birch-forest. Ash woods of Fraxinus excelsior ; semi-natural
woods an4 plantations on the limestone slopes ; trees and shrubs ;
herbaceous vegetation. Comparison of the woodland plants of the
southern Pennines. pp. 38-87

CHAPTER III

SCRUB ASSOCIATIONS

Past and present upper altitudinal limit of trees. Buried timber in the
peat. Degeneration of woodland. Distribution of character of the
existing scrub. Scrub in other districts. Relation of the ground
vegetation of woodland to retrogressive scrub. Progressive and
retrogressive scrub. Comparison of the types of retrogressive scrub.

pp. 88-102

viil CONTENTS

CHAPTER IV

GRASSLAND ASSOCIATIONS

Distribution of the grassland. Types of grassland. I. Grassland of the
sandstones and shales : siliceous grassland ; (1) Nardus grassland ;
mixed siliceous grassland ; (2) Molinia grassland. Eelationships of
the plant associations of the siliceous soils. II. Grassland of the
limestone : calcareous grassland ; mixed calcareous grassland : tran-
sitional calcareous grassland. Calcareous heath. Pseudo-calcareous
heaths. Species of the calcareous grassland and the siliceous grass-
land. Relationships of the plant associations of the siliceous and the
calcareous soils. pp. 103-133

CHAPTER V

ASSOCIATIONS OF ROCKS AND SCREES

The limestone cliffs : limestone screes. Sandstone rocks and screes. Are
the plants of cliffs and screes lithophytes ? pp. 134-143

CHAPTER VI

MARSH AND AQUATIC ASSOCIATIONS

General distribution of the marsh (or swamp) and aquatic associations.
Non-calcareous waters. Swamps on the sandstones and shales. Cal-
careous waters. Swamps on the limestone. Ruderal marsh species.
Reed swamps. The vegetation of quickly flowing streams. Alien
aquatic plants. The relation of calcium salts to the flora and vege-
tation, pp. 144-162

CHAPTER VII

MOORLAND ASSOCIATIONS

General distribution of moorland. Classification of moorland associations.
The fen formation. " Hochmoor " and " Flachmoor." Moors and
fens. Bryophytes of the moors. Factors related to the distri-
bution of the moorland associations. Heather moors. Transitional
association of heather moor and siliceous grassland. Bilberry moors.
Transitional association of heather moor and bilberry moor. Cotton-
grass moors. Transitional association of cotton-grass moor and
siliceous grassland. Transitional association of heather moor and
cotton-grass moor. Retrogressive moors. The Peak of Derbyshire.
Bare peat. Sub- Alpine grassland. Zonation of the moorland and
grassland associations. List of species of the moor formation.

pp. 163-198
CHAPTER VIII

CULTIVATED LAND : CULTURE ASSOCIATIONS

Origin of the cultivated land. Nature of the cultivated land. Perma-
nent pasture. The arable land. Plantations. Afforestation. Utili-
zation of the peat-moors. pp. 199-213

CONTENTS IX

APPENDIX I

SUMMARY AND RELATIONS OP THE PLANT COMMUNITIES
OF THE PEAK DISTRICT

1. The Plant Formation of Calcareous soils (Calcarion).

2. The Plant Formation of Siliceous soils (Silicion).

3. The Plant Formation of the Acidic Peaty soils (Oxodion).

4. The Relationships of the Oxodion and the Silicion.

5. The Plant Formation of Fresh Waters.

pp. 214-217

APPENDIX II

SUMMARY OP BRITISH PLANT FORMATIONS AND ASSOCIATIONS

pp. 218-221

APPENDIX III

List of References . ' s , - * . . . pp. 222-228

INDEX pp. 229-235

LIST OF ILLUSTRATIONS

FIGURE PAGE

1. Subsoil map of the Peak District (northern area) ... 6

2. Subsoil map of the Peak District (southern area) . . .11

3. Oak Wood of Quercus sessHiflora near its upper altitudinal

limit. Ground vegetation of Bilberry and silver Hair-
grass . . v . facing 38

4. Oak Wood of Querciis sessiliflora. Shrubby undergrowth . „ 42

5. Oak Wood of Quereus sessiliflora. Ground vegetation of

Blue-bells „ 46

6. Oak Wood of Quercu* sessiKflora. Ground vegetation of

Bracken and wood Soft-grass „ 50

7. Oak Wood of Qiiercus sessiliflora. Ground vegetation of

Bilberry and silver Hair-grass „ 54

8. Birch Wood of Betula pubescens. Ground vegetation of

Rush and tufted Hair-grass '„ 60

X LIST OF ILLUSTRATIONS

FIGURE PAGE

9. Ash Wood of Fraxinus excelsior. General view . . facing 66

10. Ash Wood of Fraxinus excelsior : society of Wych

Elms. Ground vegetation of Dog's Mercury . . .,70

11. Maps of the Vegetation of Cressbrook Dale . . . „ 74

12. A Sandstone Clough. Siliceous grassland and scrub . „ 90

13. A streamless Limestone Dale. Calcareous grassland and

scrub „ 94

14. Siliceous grassland. Blue Moor-grass and Mat-grass . „ 104

15. Siliceous grassland. Bracken abundant „ 108

16. Siliceous grassland. Rush abundant . . . . ,,110

17. Calcareous scrub and grassland „ 120

18. Ash Wood and Limestone Cliffs „ 134

19. Rocks of Millstone Grit ,,140

20. A Dripping Shaly Bank . „ 146

21. A Limestone Dale „ 152

22. Heather Moor on peat over Millstone Grit rock . . „ 164

23. Heather Moor on peat over Chert ,,168

24. Heather Moor and Upland Cultivation . . . . ,,172

25. Bilberry Moor ,,178

26. Cotton-grass Moor „ 180

27. Junction of Heather Moor and Cotton-grass Moor . . „ 182

28. Retrogressive Moor. Early stage of retrogression . . ,,184

29. Retrogressive Moor. Later stage of retrogression . . ,,186

30. Retrogressive Moor. Later stage of retrogression . . ,,188

31. Retrogressive Moor. Later stage of retrogression . . ,,190

32. Map of the Vegetation of the Peak of Derbyshire . . ,,192

33. Diagram of a flat-topped eminence in the Peak District . . 195

34. Diagram of a more pointed eminence in the Peak District . 195

35. Derelict Plantation on wet peat facing 210

36. Reservoir among the moors ,,212

Two coloured vegetation maps in pocket of cover at end

CHAPTER I

INTRODUCTION

THE Peak District has no definite geographical boundaries ;
and, for the purposes of the present memoir, it is regarded as
being co-extensive with the accompanying vegetation maps
(see also figures 1 and 2). A large proportion of the district
consists of unenclosed moorland and grassland; and there are
numerous small vestiges of scrub and primitive woodland,
besides several comparatively extensive stretches of semi-primi-
tive woodland. Cultivated land ascends the valleys, usually
up to about 1000 feet (305 m.), and occurs also as more or less
isolated " intakes " up to about 1500 feet (457 m.). Most of the
cultivated land is utilized as permanent pasture ; and there is
very little arable land. Plantations are fairly numerous ; and
a few of them are of moderately large size.

The highest elevation of the district is reached on an ex-
tensive, undulating plateau which bears the singularly inappro-
priate name of " the Peak." This plateau, the highest in
England south of the mid-Pennines, is peat-clad ; and it attains
an altitude of 2088 feet (636 m.). North of the Peak are two
summits which attain heights of more than 2000 feet (610 m.) :
one of these, known as Bleaklow Hill, is situated six miles

M. 1

2 VEGETATION OF THE PEAK DISTRICT

(9-7 km ) to the north of the Peak, and is 2039 feet (621 m.) in
height; and the second, one mile south of Bleaklow Hill and
apparently without any special name, is 2068 feet (630 m.) high.
These three are the only Pennine summits, south of the " York-
shire giants" of Whernside (736 m.), Ingleborough (723 m.), and
Pen-y-ghent (686 m.), which reach a height of 2000 feet.

The westerly slopes of the Pennines descend rather abruptly
into the lowland plain of Lancashire and Cheshire ; and this
physiographical feature is reflected on the accompanying vegeta-
tion maps by a comparatively narrow western zone of heather
moorland. On the east, the slope is more gradual; and the zone
of heather moor is correspondingly wider. The higher plateaux
are covered by cotton-grass moors and bilberry moors, and the
steeper hill slopes by uncultivated grassland. The foot of the
western slopes of the Peak District is characterized by a densely
populated manufacturing district, of which Manchester is the
centre ; and Sheffield is the centre of another manufacturing
district which lies at the foot of the eastern slopes. The
Pennine moors stretch away from the Peak in a northerly
direction; and it is almost but not quite possible- to walk
along the Pennine watershed from the Peak to the Border with-
out leaving the uncultivated land. South of the Peak lies the
sequestered valley of Edale; and to the south of this the
limestone hills and dales are situated. The limestone area is
flanked, both on the east and on the west, by a southern exten-
sion of characteristic Pennine moorland and grassland. The
lowest altitudes occur where the streams leave the district,
usually at an altitude of about 100 metres. The streams harbour
a few aquatic plants ; but the latter are, on the whole, poorly
represented on the Pennines generally.

In pre-railway days, the Pennine hills, with their peat-clad,
unfenced, and undrained summits formed an effectual barrier
between the Lancashire and Yorkshire peoples. Before the
construction of the turnpike roads, about a century ago, the
Pennines could scarcely be crossed except by the primitive
pack-horse roads. Some of these still exist as public footpaths;
but others, it would appear, have been closed, and are now
largely overgrown with rough grasses. At the present time, the
southern Pennines may be crossed by half a dozen good roads,
two canals, and four or five railways. An interesting account

I] INTRODUCTION 3

of a journey across the Pennines in the early part of the
eighteenth century is given by Defoe (1725 : 90, et seq.)1.

Portions of five counties, namely, south-east Lancashire,
north-east Cheshire, north Staffordshire, north Derbyshire, and
south-west Yorkshire, are represented in this district; and on the
high moorlands several of the head-streams of the Mersey, Dee,
Trent, and Yorkshire Ouse take their rise.

TYPES OF SCENERY

The district furnishes some interesting and distinct types
of scenery, which depend primarily on the nature of the
geological strata (cf. figures 1 and 2).

The lower hills of the north-west and north-east of the
district are composed of sandstones and shales belonging to
the Coal-measure series. It is on or near these rocks that the
manufacturing areas are situated. The hills of the Coal-measures
are usually cultivated up to their summits. Arable land, whilst
nowhere really common, is more abundant on the Coal-measures
than elsewhere ; and more wheat is grown on such soils than on
any other soils of the district. This is an interesting fact, as
the soils of the Coal-measures are usually described as cold and
backward (e.g., by Lees, 1888 : 66). The uncultivated parts of
the Coal-measures are few and often isolated, and consist usually
of heather associations on the sandstones and of grassland
associations on the shales. However, on the few areas of
uncultivated land of the Coal-measures at the higher altitudes,
heather moors and cotton-grass moors occur, as, for example,
south-west of Buxton. The differences therefore between the
vegetation of the uncultivated parts of the Coal-measures and
the other siliceous strata^ are due almost entirely to altitude,
and not to any differences either in the nature of the climate
or of the soil.

1 The first number in brackets after an author's name refers to the year pf
publication in which the book or paper, which is being referred to, was published.
The number after the colon refers to the page where the particular matter which
is referred to occurs in the original work. The pages of the quoted works refer,
as far as is possible, to the pages of the original memoirs, and not necessarily to
the pages of the separately issued copies, as these unfortunately are often paged
differently from the original. The titles, dates, and places of publication of the
works quoted will be found in an appendix (pp. 222-229).

1—2

4 VEGETATION OF THE PEAK DISTRICT [CH.

The hill slopes of the Coal-measures are rarely very steep,
and are characterized by a number of typical oak (Quercus
sessiliflora) woods which are at least semi-primitive in character.
These woods occasionally spread out for a little distance on to
the low, flat or gently sloping plateaux. The valley bottoms
are almost filled up with overgrown, manufacturing villages,
many of which have a population of twenty thousand people.
The smoke from the villages and hamlets, for even every
hamlet has its factory, frequently renders the sky dull and
the atmosphere thick and heavy. Sandstone walls as a rule,
hedgerows occasionally, separate the cultivated fields ; and the
stone walls and the tree trunks are permanently blackened with
soot and smoke which have effectually destroyed almost all
traces of mural plants, especially Cryptogams. Only in the
heart of the woods, some of which retain their original sylvan
character, may one, in this Coal-measure country, forget the
propinquity of coal-mines and mills.

The higher hills of the central massif consist of sandstones
and shales belonging to the Millstone Grit and to the Yoredale
or Pendleside (Hind, 1897, etc.; Hind and Howe, 1901) series of
rocks. Here there are fewer factories than on the Coal-measures,
and no coal-pits. The higher hill summits are unpopulated,
and covered with peat moors. Here and there, the moorland
plateaux terminate abruptly in precipitous escarpments, locally
known as "edges," formed of massive sandstone rocks. The
larger and broader valleys are known as "dales," the smaller
and narrower ones as " cloughs " or " deans," or, further north,
as " ghylls." The upland valleys shelter woods of oak (Quercus
sessiliflora), and rarely of birch (Betula pubescens) ; but more
frequently the slopes of the steep valleys are tenanted by
scrub or grassland. The bracken is a characteristic plant of
the drier slopes. The upper portions of the cloughs contain
numerous reservoirs (see figure 36) which are fed by the
streams issuing from the peat moors of the plateaux. The
lower plateaux and valleys are cultivated, chiefly as perma-
nent pasture: arable land is decidedly scarce: wheat, in
particular, is very rarely grown; and even fields of oats are
uncommon. The fields are usually separated by sandstone
walls; though, as in the Coal-measure country, hedgerows
occur where the shales are of great extent.

l] INTRODUCTION 5

In the south of the district, a third type of scenery is
occasioned by the rocks of the Carboniferous or Mountain
Limestone. The limestone plateaux are not so high as those
of the sandstones; and they are frequently cultivated up to
their summits. Limestone escarpments are frequent, and are
more or less covered with plants, many of which belong to quite
different species from those which characterize the sandstone
escarpments. The valleys are all spoken of as " dales " ; and
these are much richer in species than the "cloughs" of the sand-
stones and shales. The valley slopes are steep, and are clothed by
ash (Fraxinus excelsior) woods, or scrub, or calcareous grassland.
The limestone country is too remote from the factories to be
affected seriously by smoke. Arable land, on which oats are
commonly grown, is not rare; but wheat is practically never
grown on the Mountain Limestone. The fields are separated
by white, limestone walls which give to the country side a very
characteristic appearance.

Generally speaking, the cloughs in the shaly areas are
grassy : those of the sandstone areas are bolder, more rocky,
and more heathery. The prevailing hues of the cloughs are
warm browns and purples, those of the limestone dales cold
greys and greens, for in the latter localities, bracken, heather,
and bilberry are almost entirely absent.

ROCKS AND SOILS

The geological features of the district have been elucidated
by Green (1869 and 1887), Dale (1900), and others. Still, the
features of a district which are of chief interest to the geologist
are not necessarily those which are responsible for the differences
of the vegetation. From the latter point of view, it is the soil that
is important (cf. figures 1 and 2) ; and this is not always directly
related to the solid strata that are indicated on an ordinary
geological map. In the present district, although it is largely
unglaciated, there are several important soil features whjch
cannot be inferred from any of the existing geological maps.
Unfortunately, only geological maps of the old series are issued for
this district ; and no soil maps and no drift maps of the Peak
District have been published by the Ordnance Department. In
fact, the survey of the drift of this district does not appear to have

VEGETATION OF THE PEAK DISTRICT

[CH.

§5

I] INTRODUCTION 7

been yet commenced by the Geological Survey, though several
papers on the subject have been published by various geologists.

Considering first those soils which are directly a result of
the underlying strata, it is, so far as this district is concerned,
necessary and sufficient to distinguish two main classes,
calcareous and non-calcareous. The latter overlie the rocks of
the Pendleside series, the Millstone Grits, and the Coal-measures.
The calcareous soils overlie most of the rocks of the Carboni-
ferous Limestone.

The non-calcareous soils of the Pendleside beds, the Millstone
Grits, and the Coal-measures are here taken together, for the
soils to which they directly give rise are essentially alike in their
chemical and physical characters, and produce identical plant
associations. The rocks consist largely of coarse grains of sand,
of pebbles, of quartz, of pieces of decomposed felspar, and of
flakes of mica.

Local floristic differences may perhaps be related to the
different strata; but, in any case these differences are very
slight. Linton (1903 : 15) correctly states that the Coal-
measures " can scarcely be said to possess a distinctive flora " ;
but the plants given by Linton (op. cit.) as characteristic of the
grit are, in nearly all cases, plants confined to peat; and he
gives no list of species characteristic of the Pendleside (or
Yoredale) rocks, erroneously including these with the Carboni-
ferous Limestone. The beds of all three series of rocks consist
of alternating beds of sandstones and shales. In no other
part of the British Isles are these strata so characteristically
developed or so widespread as in the region of the Pennines.
Over the shales, the surface soils weather ultimately into a
kind of false clay, dark yellow in colour, and very slippery
when wet. The soils produced by the weathering of the sand-
stones consist, when newly formed, of yellow sand; but this
quickly becomes mixed with humus, when its colour is much
darker. Pure sand is of very limited occurrence in the Peak
District, and is almost limited to the vicinity of quarries,
where a few arenicolous, as opposed to silicolous, species
sometimes occur, such as Spergularia rubra.

Generally, the soils over the sandstones and shales are poor
in soluble mineral salts, especially calcium carbonate. Woodhead
(1906 : 376) states that soils of this type in the Huddersfield

8 VEGETATION OF THE PEAK DISTRICT [CH.

district only contain from 0'02 to 0'04 per cent, of lime. The
soil is usually rich in humus, and therefore retentive of water.
Over such soils, if left uncultivated and undisturbed, peat
inevitably develops in course of time.

The sandstones and shales are usually regarded as having
been originally formed from the waste and denuded material
of a great tract of granite. The resulting soils are of a siliceous
nature, very deficient in soluble mineral salts, whilst in texture
they are intermediate between loam and clay. The soils are
shallow, as in the case of practically all siliceous soils derived
from the Palaeozoic rocks; and the most typical vegetation
consists of grassland dominated by the mat-grass (Nardus
stricta) and the silver hair-grass (Deschampsia flexuosa).

There is a popular but quite erroneous impression that the
soils over the rocks of the Pendleside (or Yoredale) series of
the southern Pennines are calcareous ; and, in Linton's Flora of
Derbyshire (1903), the plant records are partly arranged on this
assumption. The error may perhaps be accounted for by the
fact that the true Yoredale rocks of the northern Pennines are
frequently calcareous, and by the additional fact that, on the
existing Ordnance maps of the Geological Survey on the scale
of a quarter of an inch to the mile (1 : 253,440), the rocks of
the Pendleside series and those of the Carboniferous Limestone
are indicated by the same colour. It is true that the Pendle-
side rocks of the southern Pennines occasionally show thin
bands of calcareous nodules ; but these bring about little or
no change in the vegetation.

The soil over the Carboniferous or Mountain Limestone is, in
general, strongly calcareous, as this rock is composed very largely
of molluscan shells, encrinites, and corals ; but it agrees with that
over the sandstones and shales in often being highly ferruginous,
and in giving, from place to place, a great range of variation in
water content. The highest percentages of calcium carbonate
occur on the steep hill slopes ; and this is no doubt due to the
continuous exposures of new surfaces by denudation. The
lowest percentages occur on the flatter plateaux; and this is
doubtless caused by the leaching of the upper layers of the soil,
the lime being carried away in solution to the subterranean or
telluric waters, which find a ready means of escape to lower
levels by means of the open joints of the limestone.

l] INTRODUCTION 9

Many of the plateaux marked on the geological maps as
consisting of limestone are capped by a layer of non-calcareous
chert (cf. Sibley, 1908); and such plateaux yield soils which
are essentially identical with those over the sandstones and
shales. Sometimes the soil contains a mixture of stones of the
limestone and of the non-calcareous chert ; and then lime-loving
plants occur. This agrees with the observations of Stebler
(1906) in Switzerland.

Contemporaneous igneous rocks (cf. Arnold-Bemrose, 1907)
occur in the limestone area. Although of comparatively
limited extent, they are interesting locally. For example, a
small patch of bilberry (Vaccinium Myrtillus) and of other
lime-avoiding plants occurs on an outcrop of volcanic "toad-
stone" or basalt near Miller's Dale railway station, and is
surrounded by lime-loving plants, e.g., the salad burnet (Pote-
rium Sanguisorba) growing on the limestone soil.

Of soils composed of recent deposits, there are the glacial
sands, the river alluvia, and the upland peat.

The glacial drift of this district is confined to its western
boundary. Boulder clay scarcely occurs; but non-calcareous,
fluvio-glacial sands form rather extensive deposits, chiefly near
the confluence of the rivers Etherow and Goyt. These deep
and non-calcareous sands bring about a noteworthy change in
the vegetation, as, in this district, woods of the pedunculate oak
(Quercus Robur = Q. pedunculata) occur on this soil alone. The
sands do not appear to occur much higher than about 600 feet
(183 m.). To the west of the Peak District, on the plain of
Lancashire and Cheshire, extensive glacial deposits are found,
which consist largely of boulder clay, gravel, and sand. These
deposits occur intermittently up to the crests of the hills which
face the western plain, and also up the river valleys. For
example, glacial boulders are to be found on the summit of
Spond's Hill, at 1350 feet (411 m.) ; and they also occur in the
valley of the Goyt, on the watershed, and in the valleys of the
Wye and the Dove (cf. Dale, 1900, etc.). The boulders, however,
are local in their occurrence, and bring about no appreciable
change in the vegetation. Except on its western fringe, as on
Tintwistle Moor, near Glossop, the general moorland plateau
of the Pennines south of the Aire and Calder watershed is not
glaciated. No perched blocks occur, no striae, and no roches

10 VEGETATION OF THE PEAK DISTRICT [CH.

moutonnees. It is not likely that traces of glaciation once
existed here and have been obliterated, as the moorland plateau
consists of uninhabited and unenclosed land where there is no
necessity to remove boulders. Moreover, on hills immediately
to the west, e.g., on the Macclesfield moors, and on the moors
some miles to the north, e.g., on the Ilkley moors, glacial drift,
boulders, and striae are found ; and it is inconceivable that all
traces of glacial action should have been entirely obliterated
from the moors of the central and eastern Peak District, and
not from the similar and neighbouring moors of Macclesfield and
Ilkley. It is highly probable, then, that the Peak of Derbyshire
and the high lands to the north, east, and south of the Peak,
stood up, even during the time of maximum glaciation, as a
nunatak, and that the ice-sheet fringed the hills of the west of
the district. The fluvio-glacial sands are probably attributable
to material washed out at the edge of the waning ice-sheet.
Barrow (1903 : 42) maintains that the glaciation of the
neighbouring district of Cheadle, Staffordshire, ceased much
earlier than in Northumberland and Scotland.

River alluvium, consisting generally of gravels, occurs at
the bottom of most of the larger valleys. The gravels are
non-calcareous in the valleys of the sandstones and shales, as,
for example, between Hope and Grindleford, and calcareous in
the limestone area, as, for example, in lower Monsal Dale.
They bring about no important changes in the vegetation. In
lower Monsal Dale, a calcareous alluvial flat is uncultivated, and
the plants there are such as occur on the other calcareous soils ;
and near Grindleford, where a non-calcareous alluvial plain is
also uncultivated, the plants are such as occur on the other
non-calcareous soils. At the present time, the river gravels are
mostly under cultivation, chiefly as permanent pasture ; but a
moderate quantity of wheat is grown on the gravelly alluvium
near the confluence of the two streams, the Noe Water and the
Derwent. In early times, it is not improbable that these
alluvial tracts were characterized by woods of the " alder and
willow series " (cf. Moss, Rankin, and Tansley, 1910 : 122, et seq.).

Peat occurs on the summits of the higher non-calcareous
hills, including the plateaux of chert in the limestone area, and
is fully dealt with in Chapter VII. It is remarkable that
very extensive deposits of peat in this country, both lowland

INTRODUCTION

•g-e

VEGETATION OF THE PEAK DISTRICT

[CH.

peat and hill peat, should be ignored on most of the maps of
the Geological Survey, even on their published drift maps.
However, this fact makes such vegetation maps as accompany
this memoir all the more valuable; as, on vegetation maps, the
plant associations characteristic of peaty soils are indicated ; and
thus the occurrence and distribution of peat may be inferred.

The following table summarizes the chief strata and soils
of the district, and states the general character of their
accompanying vegetation. Farmland and plantations occur, to
a greater or lesser extent, on all the rocks and soils, except on
wet peat, and are omitted from the table. Marsh vegetation
and stream vegetation also occur on all the soils; and these
also are omitted.

Geological Strata

Soils

Vegetation

I. Carboniferous
or Mountain Lime-
stone rocks

b. Volcanic rocks

c. Chert

d. Refuse heaps
("rakes") of old lead
mines and of recent
spar and gravel pits

1. On steep slopes, es-
pecially those below 1000
feet (305 m.) :— shallow,
brown, ferruginous, cal-
careous marls or gravels

2. On more or less
level ground, especially at
elevations greater than
1000 feet :— shallow, dark
brown, highly ferruginous,
and more or less leached
marls

Non - calcareous soils
varying from soft gravels
to a kind of false clay,
light brown or black in
colour

(c i) Non-calcareous soils
varying from hard gravels
to a kind of false clay,
reddish brown in colour,
or black when mixed with
much acidic humus

(c ii) Peat, rarely exceed-
ing one foot (30-5 cm.) in
depth

Loose calcareous and
cherty gravels containing
salts and oxides of lead

1. Ash woods,
scrub, calcareous
grassland

2. Scrub, calcare-
ous grassland, cal-
careous heath

Siliceous grassland

(c i) Siliceous grass-
land, siliceous grass-
land mixed with
heather

(c ii) Heather moor,
heather moor with
much cotton-grass

Open plant associa-
tions usually charac-
terized by the lead-
wort ( Arenaria verna)
in abundance

INTRODUCTION

Geological Strata

Soils

Vegetation

II. Pendleside

Non-calcareous, ferru-

Birch (Setulapubes-

[Yoredale] rocks : —

ginous sands, gravels, and

cens) woods and scrub,

A. Sandstones

shales, which at the sur-

oak (Quercus sessili-

B. Shales

face degenerate into a kind

flora) woods and

III. Millstone Grit

of false clay, or which may

scrub, siliceous grass-

rocks :—

be mixed with much acidic

land, siliceous grass-

A. Sandstones

humus : the colour varies

land with much hea-

B. Shales

from yellowish brown to

ther

IV. Coal-measure

black according to the

rocks : —

amount of humus present

A. Sandstones

B. Shales

V. Recent soils : —

a. Glacial sands

(a) Yellowish non-cal-

(a) Oak (Quercus

careous sands, often mixed

Robur) woods, scrub,

with acidic humus

siliceous grassland

6. River gravels

(6 i) Yellowish, non-

(b i) Stream-side

calcareous, sandy gravels

scrub and siliceous

grassland

(b ii) Calcareous gra-

(b ii) Stream -side

vels and tufa

scrub and calcareous

grassland

c. Upland peat

peat, of a depth of 15 feet

cotton-grass moors,

(457 cm.) or more, and

bilberry moors, re-

usually very wet

trogressive moors

SOILS AND THEIR CHARACTERISTIC PLANTS

It will be seen that the soils of the southern Pennines fall
into three main types, namely, calcareous soils, siliceous soils,
and peaty soils. The ground waters of the calcareous soils are
alkaline in reaction, those of the siliceous soils neutral or acid,
and those of the peaty soils of this district always acid. The
siliceous and peaty soils of the district are more closely related
to each other than either is to the calcareous soils, not only
by the acidity but also by their low, soluble mineral-content
and by their floristic composition. There is also every stage of
transition from acidic siliceous soils to the acidic peaty soils;
and in the following table of plants characteristic of (though
not in all cases absolutely confined to) each kind of soil, several
species are necessarily given as characteristic both of siliceous
and of peaty soils.

VEGETATION OF THE PEAK DISTRICT

[CH.

Calcareous soils

Siliceous soils

Acidic peaty soils

Asplenium viride
A. Trichomones
A. Kuta-muraria
A. Adiantum-nigrum
Ceterach officinarum
Phyllitis Scolopendrium
Cystopteris fragilis
Polypodium vulgare
Phegopteris Robertiana

Taxus baccata

" Juniperus communis"

Silene nutans
Arenaria verua
Helleborus viridis
H. foetidus

Ranunculus circinatus
R. fluitans
R. trichophyllus
R. Drouettii
Thalictrum minus
T. flavum

*Cheiranthus Cheiri
Arabia hirsuta
*A. albida
" A. perfoliata "
Cardamine impatiens
Draba muralis

D. incana
Erophila verua

E. praecox
"E. inflate"
Cochlearia alpina
Thlaspi alpestre

var. sylvestre

var. virens
*Iberis amara
Hutchinsea petraea
Sedum acre
" Saxifraga sphonhe-

mica "

S. Telephium
S. hypnoides
S. tridactylites
Parnassia palustris
Ribes alpinum
Spiraea Filipendula
" PotentiUa verna "

Equisetum sylvaticum
" Osmunda regalis "
Pteris aquilina
Cryptogramma crispa
Athyrium Filix-foemina
Nephrodium monta-
num

Salix repens
S. aurita
Betula pubescens
Quercus sessiliflora
Montia fontana
Spergula arvensis
Spergularia rubra
Stellaria uliginosa
Ranunculus Flamraula
R. Lenormandi
Corydalis claviculata
Rubus spp.
R. Idaeus
PotentiUa erecta
P. procumbens
Cytisus scoparius
Genista anglica
Ulex Gallii
Polygala serpyllacea
Empetrum nigrum
Ilex Aquifolium
Hypericum humifusum
Viola palustris

"Lycopodium alpi-
num"1

" L. inundatum "
Blechnum spicant

Salix repens
Ranunculus Flammula

var. tenuifolius
Drosera rotundifolia
PotentiUa erecta
Rubus Chamaemorus
Genista anglica
Ulex Gallii
Empetrum nigrum
Viola palustris

Poterium Sanguisorba
i Throughout this work, the names of species 'included within inverted
imas are taken from Linton's Flora of Derbyshire (1903) : names of species
which are not indigenous are preceded by an asterisk.

INTRODUCTION

Calcareous soils

Siliceous soils

Acidic peaty soils

Rosa spinosissima
Pyrus Aria
Anthyllis Vulneraria
Hippocrepis comosa
Ononis spinosa
Geranium lucidum
G. sanguineum
Euonyrnus europaeus
Rhamnus catharticus
Hypericum hirsutum
H. montanum
Helianthemum Cha-

maecistus
Viola hirta
V. sylvestris
V. Riviniana
var. villosa
Cornus sanguinea

Ligustrum vulgare
Polemonium coeruleum
Myosotis collina
Lithospermum officinale
Origanum vulgare
Thymus Serpyllum
Satureia Acinos
S. Calamintba
Atropa Belladonna
Verbascum Thapsus
Plantago media
" Rubia peregrina "
Galium sylvestre
var. nitidulum
Asperula cynanchica
Valerianella olitoria
V. carinata
Dipsacus pilosus
Scabiosa Columbaria
Campanula Trachelium
C. glomerata
Inula vulgaris
Arctium nemorosum
Carduus nutans
Cirsium eriophorum
Centaurea Scabiosa
Picris hieracioides
Hieracium spp.

Avena pubescens
A. pratensis
Koeleria cristata (agg.)
Melica nutans

Vaccinium Myrtillus
Erica cinerea
Calluna vulgaris
Myosotis repens
Scutellaria minor
Digitalis purpurea
Galium saxatile
G. Witheringii
Valeriana sambucifolia
Jasione montana
Wahlenbergia heder-

acea

Gnaphalium uliginosum
G. sylvaticum
Senecio sylvaticus

Andromeda Polifolia
Arctostapbylos Uva-ursi
Vaccinium Myrtillus
V. Vitis-idaea
V. Oxycoccus
Erica cinerea
E. Tetralix
Calluna vulgaris

Agrostis canina
Holcus mollis
Deschampsia flexuosa
Molinia caerulea

Potamogeton polygoni-

folius

Agrostis canina
Molinia caerulea

VEGETATION OF THE PEAK DISTRICT

[CH.

Calcareous soils

Siliceous soils

Acidic peaty soils

Bromus erectus
Brachypodium pinna-
tum

Nardus stricta
Carex helodes
C. binervis

Nardus stricta
Eriophorum vaginatum
E. angustifolium

Scirpus compressus
Carex disticha

C. echinata
C. panicea

Scirpus caespitosus
Carex canescens

C. ornithopoda

C. Qoodenowii

C. echinata

Allium vineale

C..flava (agg.)

C. panicea

A. oleraceum

Luzula maxima

C. Qoodeuowii

Polygonatum multi-

L. multiflora

C. flava (agg.)

florum

forma congesta

var. minor

P. officinale

Juncus effusus

Juncus squarrosus

Convallaria majalis
Paris quadrifolia

J. supinus
Orchis ericetorum

Narthecium osaifragum
" Listera cordata "

" Cypripedium Calceo-

lus" (extinct)

Ophrys apifera

O. rnuscifera

Orchis ustulata

O. pyramidalis

Helleborine atrorubens

The Peak District has been well studied from the floristic
standpoint, for each county represented, with the exception of
the small portion which occurs in south Lancashire, has its
published local flora. Those of west Yorkshire (Lees, 1888),
Cheshire (de Tabley, 1899), and Derbyshire (Linton, 1903) may
be taken as representative, in various ways, of the best of the
British county and local floras; and those by Painter (1889)
and Bagnall (1901) provide useful lists of species. The flora
by Crump and Crossland (1904), although it deals with an area
a little to the north of this district, may be taken as illustrating;
the flora of the non-calcareous soils of the southern Pennines
generally; and it shares, along with Wheldon and Wilson's
flora (1907), the honour of being one of the very few British
floras which deal at some length with the occurrence and
distribution of plant associations.

Whilst, however, the flora of the Peak District has been
dealt with by several authors, its vegetation has not been
described. The distinction between flora and vegetation was

I] INTRODUCTION 17

emphasized by many of the older plant geographers, notably
by Humboldt, A. P. de Candolle, Grisebach, and Thurmann.
Thurmann stated (1849: 22) that "la Flore s'entend surtout
du nombre des formes ve"g6tales distinctes qu'on y observe, la
V^g^tation de leurs proportions et de leur association." From
a flora, a knowledge is gained of the occurrence and distribution
of the species of a district, of their presence or absence in
contiguous districts, of the stations of these species, of the
general nature of their habitats, of the altitudes to which
they ascend, of their comparative abundance or rarity, of
their times of flowering, and of their rank (i.e., whether they
are indigenous or not). So much may be expected of any
flora which has pretensions to be a scientific work. In some
floras, hints are given as to why certain species are confined
to certain kinds of habitats : mention" is made of those which
are dominant over particular tracts of country : the floristic
(not merely the topographical) subdivisions of the district
covered by the flora are outlined; and some idea is given of
the original migrations of the species into the district in
question. Some modern floras rightly furnish details with
regard to the very closely allied or " elementary species "
which occur in the district, and state how these may be
distinguished, whether or not their characters appear to be
constant, and whether or not the plants in question are confined
to special habitats.

The flora is composed of the individual species : the vege-
tation comprises the groupings of those species into ensembles
termed vegetation units or plant communities.

A botanist who frequently traverses any stretch of unr
cultivated land, such as the elevated lands of the Peak District,
must recognize sooner or later that the plants have become
arranged in definite vegetation groups or plant communities.
For instance, in the present district, the gentle slopes of the
edges of the peat moors are almost entirely monopolized by
heather (Calluna vulgaris), the higher peat moors by cotton-
grass (Eriophorum vaginatum), and the highest and most
exposed ridges by bilberry ( Vaccinium Myrtilliis). Here then
he may distinguish three plant associations which he may
term respectively heather moor, cotton-grass moor, and bilberry
moor. These associations he finds to be constant both as

18 VEGETATION OF THE PEAK DISTRICT [CH.

regards their floristic composition and their general life con-
ditions. Similarly, he may easily recognize other plant
associations on the hill slopes of the district.

VEGETATION MAPS

In this way the observer determines that certain plant
associations are typical of certain limited areas ; and it becomes
possible to construct vegetation maps on which the distribution
of these associations may be shown. The number of the plant
associations which may be indicated on a map depends very
largely upon its scale. The bigger the scale of the map the
more the plant associations which may be shown upon it ; and
considerable judgment is required in deciding which associa-
tions shall be shown on a map of any given scale. In deciding
this difficult but very important question, several general con-
siderations must be borne in mind.

The object of a vegetation map of a district under investiga-
tion is to give the best possible cartographical representation
of the plant communities which the scale of the map will allow.
On the one hand, the fullest advantage must be taken of the
size of the scale employed ; and, on the other hand, the map
must not be so crowded with details that it loses in definiteness
and clearness (cf. Flahault and Schroter, 1910: 11). The
experience of phytogeographers in this country is that the
scale of one inch to the mile (1 : 63,360) is a suitable one for
maps intended to show the distribution of the more important
plant associations of the British Isles, and that maps of a
smaller scale are not desirable except for special purposes.

It is obvious that every plant community cannot be indicated
on a map of this scale (1 : 63,360); and hence the plant
geographer has frequently to subordinate minor units of
vegetation to units of wider significance; and, in such cases,
the plant geographer has to determine the larger vegetation
units to which the minor units must be subordinated : other-
wise, the colours on a vegetation map will be mere empiricisms
and without any philosophical basis. It is obvious, therefore,
that no one can successfully construct a really scientific
vegetation map unless he has specially considered the inter-
relationships of the fundamental units of vegetation.

I] INTRODUCTION 19

PLANT COMMUNITIES .

A plant formation is the whole of the vegetation which
occurs on a definite and essentially uniform habitat. A plant
association is of lower rank than a formation, and is characterized
by minor differences within the generally uniform habitat. ' A
plant society is of lower rank than an association, and is marked
by still less fundamental differences of the habitat. These
grades of difference of the habitat are marked by corresponding
differences in floristic composition. The three vegetation units
may be compared respectively with the taxonomic units of the
genus, the species, and the variety ; and differences of opinion
arise, both among systematic and geographical botanists, with
regard to the precise limits of the respective units. Sub-
formations and sub-associations may be recognized; and these
would be comparable to subgenera and subspecies. Plant
community is a convenient and general term used for a vege-
tation unit of any rank.

Examples of the above types of plant communities are
well illustrated in the present district. The acidic peat of the
non-calcareous plateaux of the district furnishes a definite and
generally uniform habitat; and the whole of the vegetation
of this habitat is the plant formation of the acidic peat moors.
The plant associations of Calluna vulgaris (i.e., heather moor),
of Eriophorum vaginatum (i.e., cotton-grass moor), and of
Vaccinium Myrtillus (i.e., bilberry moor) are subdivisions of
this plant formation, and are characterized by minor differences
within the generally uniform habitat and by corresponding
differences in floristic composition. Still less important
differences in the habitat may cause certain members of the
associations to become locally dominant; and thus, in the
heather moor, for example, plant societies, or mere local
aggregations of species, occur of Erica cinerea, of Juncus
squarrosus, of Carex Qoodenowii, and of other species.

For the purpose of vegetation maps on a scale of one inch
to the mile (1 : 63,360), the most important vegetation unit
is the association, as it is, in general, possible to indicate the
more important associations on a map of this scale. To indicate
the smaller associations and the plant societies, maps on a

2—2

20 VEGETATION OF THE PEAK DISTRICT [CH.

scale of six inches to the mile (1 : 10,560) are desirable ; and,
on maps whose scale is a quarter of an inch to the mile
(1 : 253,440), plant formations could, in general, only be shown.
It is extremely doubtful if vegetation maps of limited areas on
a scale much smaller than this can be constructed on a strictly
scientific basis until some method of classifying formations into
larger but natural vegetation units has been devised.

A plant association is a closed association when the ground
is fully occupied by plants, and when it is dominated either by
a single species, as in the case of a heather moor, or by two
or more species all belonging to the same plant form, as in the
case of some reed swamps. A plant association is an open
association when the ground is only partially covered with
vegetation, as in the case of denuding peat moors. Other
associations are intermediate in character between open
associations and closed associations. In an intermediate associ-
ation, the ground may be more or less fully covered with
plants ; but there is no single dominant plant or plant form :
there are, in fact, several plants which compete with each other
for dominance, as on an East Anglian fen, where Gladium
Mariscus, Phragmites communis, Molinia caerulea, Calam-
agrostis canescens, Juncus subnodulosus, and other plants compete
in this way. Differences in a single association caused by the
varying abundance of the constituent species may be spoken of
as the fades of an association. When, in a plant association, the
more abundant species become very conspicuous at different
times of the year, seasonal aspects of associations are produced
(cf. Clements, 1905 : 296 and 315).

If the succession of associations within a single formation
is studied, it is found that the initial stages are marked by
open and unstable associations, that these are followed by inter-
mediate associations, and these again by stable associations (cf.
Clements, 1904: 135; Moss, 1907 a: 12). The stable associations,
however, may degenerate, and give rise to other intermediate
associations. In the present account of the vegetation of the
Peak District, the associations will be considered from this point
of view ; and accordingly the following terminology will be used.
Open and intermediate associations leading up to a stable asso-
ciation are termed progressive associations: intermediate and
open associations resulting from the decay of a stable association

l] INTRODUCTION 21

are termed retrogressive associations : progressive and retrogres-
sive associations together are termed subordinate associations',
and the stable associations are termed chief associations. The
latter are virtually the "climatic formations" of Cowles (1911 :
161), but not those of Schimper (1903 : 161).

" Every formation has at least one chief association : it may
have more ; and they may be regarded (cf. Drude, 1896 : 286)
as equivalent to one another in their vegetational rank. They
are more distinct and more fixed than progressive or retro-
gressive associations. They are usually, but not invariably1,
closed associations. They always represent the highest limit
that can be attained in the particular formation in which they
occur, a limit determined by the general life conditions of
the formation. In desert and sub«niveal regions, the chief
associations are open1; and, in such cases, it is legitimate to
speak of open formations. Open progressive and retrogressive
associations, however, frequently occur in formations whose
chief associations are closed" (Moss, 19106: 38).

Every part of a plant formation necessarily belongs either
to one of its subordinate associations or to one of its chief
associations.

A plant association, whether open or closed, which is
characterized by a single dominant species, is spoken of as a
pure association, one characterized by several species competing
for dominance as a mixed association.

A plant formation has a life- history. It is born : it enters
on a period of infancy and adolescence, that is, of progressive
associations : it reaches a period of maturity, that is, of chief
associations : it passes through a period of senility or decay,
that is, of retrogressive associations; but throughout these
stages, it is the same organism characterized by a definite
habitat which is related to a correspondingly definite flora.

Much discussion has taken place as to whether or not a
particular plant formation may be world- wide in its distribution.
From the point of view here taken, climatic factors and geo-
graphical position are regarded as part of the habitat ; and
it follows that any particular plant formation is confined to a
single climatic or geographical region.

1 Hence the statement that "for each habitat there is a closed, ultimate, or
chief association " (Bot. Centralblatt, 1911 : 100) is erroneous.

22 VEGETATION OF THE PEAK DISTRICT [CH.

Each of the succeeding chapters deals with a group of
associations, not necessarily with a formation. The associations
are analysed; and, as far as is possible, each association is
then referred to the formation to which it belongs.

VEGETATION MAPS AND FLORISTIC MAPS

Vegetation maps indicate the occurrence and distribution
of plant communities. Floristic maps may be of two kinds :
they may indicate the occurrence and distribution of single
species or of groups of geographically related species. The
former maps are of the type which H. C. Watson (1832, etc.)
began to construct of the species indigenous to the British
Isles. They are very useful maps in their way, as may be seen
by the use to which they are put in Praeger's recent Flora of
the West of Ireland (1909: figs. 4, 5, 14, etc.). Such maps,
however, do not lend themselves to any generalized carto-
graphical scheme, because almost every species requires a
separate map to show its distribution. They bear the same
relation to vegetation maps that a series of cartographical
representations of erratic boulders would bear to a modern
geological drift map. Floristic maps illustrating the distribution
of geographically related species can hardly be said to exist as
regards the British Isles; but Flahault (1901) has constructed
such a map of France, and more recently Massart (1910) has
published maps of Belgium on somewhat similar lines.

The so-called "botanical maps" illustrating numerous
British county and local floras are neither floristic maps nor
vegetation maps. The typical maps accompanying these floras
simply show divisions of the county into " drainage districts "
or other topographically convenient districts ; and no attempt
is made on such maps to show the occurrence and distribution
either of plant communities or of floristic groups of species.

THE VALUE OF VEGETATION MAPS

Vegetation maps have the same value to botanists that
geological maps have to geologists. Just as geologists may,
by consulting geological maps, know where certain geological
phenomena may best be studied, so botanists may, by consulting
vegetation maps, know where certain ecological phenomena

I] INTRODUCTION 23

may best be investigated. Geological maps show the nature
and distribution of the chief rock strata ; and vegetation maps
indicate the nature and distribution of the principal plant
communities. Geological memoirs describe the development
and structure of the strata shown on the geological maps, and
give lists of the fossils found in the deposits; and similarly
vegetation memoirs give accounts of the development and
structure of the plant communities, and furnish lists of the
species which constitute the various units of vegetation.

The nature of the surface soil of a district may often be
inferred from vegetation maps (cf. p. 12), even when the existing
geological maps are not helpful in this regard, as is frequently
the case.

Geographers too find the maps of service, as has recently
been testified by Professor A. J. Herbertson, who states that
"at last we have some modern botanical geography which is
really valuable to the geographer" (Herbertson, 1911: 384).

The maps are also valuable to scientific agriculturists, who
find on them the limits of profitable wheat cultivation mapped
with very considerable accuracy (cf. pp. 204 — 5).

The forester may, from the nature of the natural and semi-
natural woods shown on vegetation maps, obtain valuable data
with regard to the prospects of success of planting certain
indigenous or non-indigenous timber trees in any particular
locality ; and, to those interested in any future great scheme
of afforestation, the vegetation maps which have been published
will yield extremely valuable information (cf. p. 68).

Vegetation maps furnish the only reliable knowledge which
is at present available with regard to the nature and possible
utilization of the " waste lands " of the country. The Board of
Agriculture has at its disposal an almost unlimited amount of
information, much of which is published in their annual Agri-
cultural Returns, with regard to the cultivated lands of the
country; but, apart from unofficial vegetation maps and
memoirs, there are practically no means of obtaining reliable
knowledge of the nature and possible utilization of the un-
cultivated land of any portion of the British Isles.

Whilst, however, the geological survey of the country is
carried on by public funds, the vegetation survey languishes
under voluptary efforts. There are at present about twenty

24 VEGETATION OF THE PEAK DISTRICT [CH.

finished vegetation maps of different parts of Great Britain,
such as the Isle of Wight, Hampshire, the Cleveland District
of Yorkshire, and Lanarkshire; and these maps cannot at
present be published owing to lack of funds. The time seems
to be approaching, therefore, for placing a vegetation survey
of this country on the same official basis as the existing
geological survey.

RAINFALL1

There are not enough rainfall stations in the district,
especially in the moorland region, with sufficiently long and
continuous records to justify the construction of a map showing
rainfall lines. Dr H. R. Mill, however, has kindly supplied the
following statistics giving yearly and monthly averages for
thirty years at ten stations distributed as regularly as possible
over the area covered by the vegetation maps. The figures
given on the following page represent the average rainfall to
the nearest inch, during the thirty years 1870 — 1899. The
particular rainfall stations have been selected by reason of the
fact that they possess long and accurate records; and the yearly
figures may be taken as satisfactory for the stations in question.
A slightly greater rainfall may be safely assumed to occur on
the higher grounds and on the leeward side of the highest hills.
The figures showing the monthly averages may be taken as
fairly satisfactory; but experience shows that for monthly
rainfall figures to be fully satisfactory, fifty years or more are
required, because a rainfall equal to the monthly average may
occur in a single day, and because, on the other hand, a month
may have no rainfall at all. The monthly rainfall of Burton-
on-Trent (see the left-hand column) is added in order to furnish
a comparison with a neighbouring town situated at a low
altitude.

It will be seen from the figures in the table which follows
that the first five months of the year are the driest, and that
the driest of all is April, in spite of a popular opinion to the
contrary. The soil, however, is often very wet during these
months, owing to low evaporation. Of the remaining seven
wet months, October is, in this district, by far the wettest.

This section has been kindly revised by Dr H. B. Mill, the Director of the
British Rainfall Organization, and Editor of British Rainfall.

INTRODUCTION

Although rainfall stations are not numerous on the hills of north
Derbyshire, Dr Mill (vide Linton, 1903 : 3) thinks that " average
falls exceeding fifty inches (127 cm.) in the year occur at several
points in the high ground; but it is unlikely that so great a
rainfall as sixty inches (152 cm.) is reached."

Average Monthly Rainfall for the 30 years, 1870 — 1899

"fl

iHtllj',

•

2
kg

00
V

13
1

mires

2
"®

sirchworl

dleworth

Months

—
0

•1

i— i

in.

in.1

in.

2-11

January

2-81

2-92

4-47

3-33

3-37

3-20

4-07

3-18

3-50

3-63

1-64

February

2-29

2-46

3-38

2-85

2-62

3-50

2-76

2-57

2-76

1-59

March

2-69

2-35

3-80

3-04

3-00

2-92

3-71

2-80

3-07

2-91

1-85

April

2-07

2-14

2-75

2-33

2-82

2-25

3-09

2-50

2-37

2-46

2-21

May

2-78

2-42

3-33

2-78

2-92

2-71

3-35

2-61

2-54

2-67

June

3-38

2-84

3-62

3-22

3-18

3-17

3-66

3-02

2-77

3-19

2-73

July

3-83

2-83

4-14

3-77

3-44

3-57

4-20

3-28

3-59

3-41

2-90

August

3-86

3-19

4-56

3-96

3-54

4-01

4-44

3-23

3-95

3-79

2-62

September

3-80

2-92

4-44

3-77

3-55

3-86

4-65

3-48

4-03

3-81

3-07

October

4-26

4-52

5-55

4-50

4-90

4-64

5-85

4-66

4-64

4-79

2-31

November

3-39

3-37

5-00

3-82

3-81

3-58

5-06

3-77

3-71

3-78

2-31

December

3-51

3-26

5-13

3-99

3-81

3-68

4-60

3-60

3-74

3-93

28-01

Total

38-67

35-22

50-17

41-36

41-19

40-21

50-18

38-89

40-48

41-00

SMOKE

The district, lying as it does between the great coalfields
and manufacturing districts of south Lancashire, and south-west
Yorkshire, possesses an atmosphere which is frequently vitiated
by smoke. The greasy soot settles on the leaves and stems of
plants, and gives them a permanently dirty appearance. A clean
expanse of white snow on the hills is often palpably blackened
in two or three hours' time. Mr A. Wilson (1900) has stated
that "the great smoke drift from south and east Lancashire
could be seen crossing the Pennine Range of moorlands, and

1 10 inches = 25-4 centimetres.

26 VEGETATION OF THE PEAK DISTRICT [CH.

then mingling with the West Riding smoke." Dr Cohen (1900,
1909) has investigated the smoke nuisance in great detail, and
he emphasizes the view that the smoke lessens the amount of
bright sunshine and lessens the temperature, even at some
distance from the towns.

The reduction of light intensity by smoke does not, of
itself, affect vegetation adversely, as, at ordinary temperatures
and with the available amount of carbon dioxide, the natural
illumination is greatly in excess of the amounts which plants
utilize in their photo-synthetic activities; but the reduction
of temperature which results from a smoke-laden atmosphere
must adversely affect the carbon assimilation of plants and
reduce their vitality. The clogging of stomata by grease and
soot would also seem to be a factor of importance, as this must
lessen the quantity of carbon dioxide which the plants can
obtain; and it is known that plants are able to utilize more
carbon dioxide than is ordinarily available. It is also known
that in smoke, certain injurious acids, e.g., sulphurous acid
(H2SO8), are present, and that these have a poisonous effect on
plants. Further, the soil is also injured by smoke on account
of the sulphurous and other acids being deposited upon it. The
injurious effects of fog on plants have been fully investigated
and discussed by Professor F. W. Oliver (1893).

Whether or not the deleterious influence of smoke is a
limiting factor as regards the plant associations of the district
is doubtful, as it seems likely that all the associations may be
affected to an equally adverse degree. On the other hand,
Wilson (I.e.) shows that certain Cryptogams (e.g., Ulota spp.
and Orthotrichum spp. and lichens) are much rarer than
formerly ; and, in certain cases, he attributes this fact to smoke.

TEMPERATURE

Judging from the figures in the standard physical atlases
(see Bartholomew and Herbertson, 1899), the mean annual
temperature of the district is about 49° F. (9'44° C.). This may
be compared with the mean annual temperature of Penzance
(see Davy, 1909 : xx) which is 52'68° F. (11'50 C.). January,
with an average temperature of 36° F. (2'2° C.), is the coldest
month of the year, and July, with an average temperature of

I] INTRODUCTION 27

62° F. (16*6° C.), the warmest. According to Lees, the average
daily range of temperature in the West Riding of Yorkshire
(the south-west of which is included in the present district)
is about twelve or thirteen degrees F. (7 '2° C.) in the shade,
and about thirty-two to thirty-four degrees F. (18'9° C.) under
exposure to the direct rays of the sun (Lees, 1888 : 6). These
temperatures, it should be remembered, are corrected to sea level,
and hence do not show the actual temperatures of the district.

Phenological observations show that the opening of spring
flowers and the unfolding of the leaves of trees is from two to four
weeks later on the Pennines than in the lowlands of Somerset,
and from ten days to three weeks later than in Cambridgeshire.

The winter on the Pennine uplands is a long one, lasting, as
a rule, from the beginning of November to the beginning of
May, though snow does not, as a rule, lie very long on the
ground, owing to intervals of mild weather. Although some
moorland plants, such as the bilberry (Vacdnium Myrtillus),
the crowberry (Empetrum nigrum), and the cotton-grasses
(Eriophorum vaginatum and E. angustifolium) flower in late
April and early May, the plants of the moorlands make very
little new growth before June and July.

THE UPPER ATMOSPHERE

I am indebted to Professor A. Schuster, F.R.S., for kindly
supplying me with the reports (Schuster, 1908-9) for the years
1908 and 1909 of the investigation of the upper atmosphere
conducted by the meteorological department of the Victoria
University of Manchester. This investigation was begun on
January 1st, 1908. The meteorological station is situated near
Glossop, in Long. 1° 57 W. and Lat. 53° 24 N., at a height of
335 metres (1100 feet, approx.) above sea level. The details
which are here utilized consist of readings of temperature,
direction and velocity of the wind, and the humidity of
the air, at altitudes respectively of 335 metres (1100 feet),
500 metres (1640 feet), and 750 metres (2460 feet). The
readings of the higher altitudes were obtained by means of
kites and balloons; and the figures utilized represent only a
small proportion of the total number of observations made by
Professor Schuster and his staff".

28 VEGETATION OF THE PEAK DISTRICT [CH.

The readings at 335 metres may be taken as indicating, in a
general way, the conditions which prevail at the present upper
limit of woodland, in the scrub and grassland associations, and
in the heather association. Those at 500 metres may similarly
be regarded as illustrating the conditions which prevail in
the cotton-grass association, and those at 750 metres the con-
ditions a little above the bilberry and retrogressive moorland
associations.

It is necessary to point out that most of the readings here
reproduced were taken during the afternoons. Hence, as
regards temperature, the figures roughly represent maxima.
The figures relating to the direction and velocity of the wind
may be taken as fairly satisfactory averages of the periods which
they represent ; and those relating to the humidity of the air
also represent fairly satisfactory averages of readings taken
during the daytime. It is obvious that observations are
required for many more years before real averages may be
deduced ; but, so for as the figures go, some interesting results
are indicated.

Temperatures

In accordance with expectation, there is a decrease in
temperature as the higher altitudes are reached; but this
decrease is greater, than would have been predicted by Dal ton's
rough and ready rule. This rule states that the temperature
falls 1° F. for every ascent of 300 feet (91 '4 m.). However,
from the figures shown on the next page, it may be calculated
that, in 1908 and 1909, on the hills of the Peak District,
the actual fall of temperature for every ascent of about
300 feet was very much greater than this. Of course, many
more readings are necessary before any rule, which accurately
represents the real phenomenon, can be stated.

December, January, February, and March are shown by the
following tables to be cold months with combined averages of
2-6°, 1*8°, and 0'5° C. at the three altitudes respectively, during
the two years. May, June, July, August, September, and
October are warm months with similar averages of 12'9°, 10'9°,
and 8'9° C. ; and November and April are intermediate, with
similar averages of 5 '9°, 47°, and 27° C.

The coldest day of 1908 was December 29th, when tem-
peratures of - 7-2°, - 7-8°, and - 9'4° C. were registered at the

INTRODUCTION

three altitudes respectively. In 1909, the coldest days were
(1) February 12th, when - 2'2°, -3'6°, and -5'6° C. respectively
were registered, (2) March 4th, when — 5'0° and — 6'1° C. were

At 335 metres

At 500 metres

At 750 metres

1908

Days1

Degrees
in C.

Days1

Degrees
in C.

Days1

Degrees
in C.

January

2-3

1-8

1-1

February

3-5

2-4

0-5

March

3-1

1-8

O'l

April

5-9

4-2

2-0

May

12-4

10-6

8-3

June

15-1

13-0

10-7

July

20-1

13-5

11-6

August

13-0

11-5

9-7

September

12-1

10-7

8-7

October

11-7

10-9

10-2

November

5-6

5-2

4-0

December

3-4

2-6

2-1

Average

9-0

7-4

5-8

1909

January

2'2

1-4

-0-2

February

1-6

0-7

-o-i

March

2-2

1-2

-0-2

April

8-0

6-1

3-6

May

11-6

9-6

6'8

June

11-0

8-8

6-6

July

13-7

12-3

10-0

August

13-7

11-9

9-7

September

11-8

10-1

8-1

October

9-0

7-3

5-9

November

4-2

3-3

1-1

December

2-2

2-1

0-9

Average

7-6

6-2

4-4

1 The numbers in these columns represent the number of days on which
readings were taken. No readings were taken on Sundays ; and occasionally
readings could not be taken on other days, sometimes owing to accidents to the
kites and balloons, and occasionally owing to requests from the landowner
during the grouse-shooting season.

VEGETATION OF THE PEAK DISTRICT

[CH.

registered at the two lower altitudes1 respectively, and
(3) December 21st, when — 5'4° C. was registered at 335 metres1.

On the days when observations were made, the temperature,
during 1908, did not fall to zero (C.) from May to November
inclusive, nor, during 1909, from April to October inclusive.

The following table shows the number of days during 1908
and 1909 when the temperature failed to rise above zero at
an altitude of 350 metres : —

January
February
March
April
November
December

1908

1909

11 days out of 26
2 days out of 25
1 day out of 23
2 days out of 25
0 days out of 25
6 days out of 27

7 days out of 25
12 days out of 24
7 days out of 27
0 days out of 22
2 days out of 22
6 days out of 24

Total

22 days out of 151

34 days out of 144

There is very little growth discernible in the vegetation of the
Peak District at altitudes above about 1100 feet (335 m.) until
the month of May : growth almost ceases in October ; and from
November to April inclusive, weather of a wintry type alter-
nating with moderately mild intervals may be expected. These
are much more severe conditions than exist in the lowlands, and
are doubtless related to the meagre flora of the uplands, as
the edaphic conditions of both the lowlands and the uplands of
England in the latitude of the southern Pennines are practically
identical.

Direction of the Wind

The figures in the tables on p. 31 are arranged to show, as far
as is possible, the relative prevalence of warm and moist winds,
i.e., westerly and southerly winds (N.W. to S.S.E.) and of dry
and cold winds, i.e., northerly and easterly winds (S.E. to
N.N.W.). It will be seen that the warm and moist winds
prevail approximately on two days out of every three, and that
(as might have been predicted) there is little change of direction
at the three chosen altitudes. Direction of wind therefore is
1 Readings at the upper altitudes on these days were incomplete.

INTRODUCTION

At 335 metres

At 500 metres

At 750 metres

Direction of

wind

Days

N.W.i

S.E.

Days

N.W.

S.E.

Days

N.W.

S.E.

1908

S.S.E.

N.N.W.

S.S.E.

N.N.W.

S.S.E.

N.N.W.

January

February

March

April

May

June

July

August

September

October

November

December

Total

308

207

101

309

207

102

293

198

1909

January

February

March

April

May

June

July

August

September

October

November

December

Total

302

208

300

200

100

293

191

102

1 To be read clockwise.

VEGETATION OF THE PEAK DISTRICT

[CH.

not to be regarded as a factor of importance in its relations to
the differential distribution of the plant associations within a
limited area, but rather as a factor which is fairly constant over
extensive districts. As a limiting factor, therefore, it only
becomes significant when different geographical or climatic
districts are under comparison.

Velocity of the Wind

At 335 metres

At 500 metres

At 750 metres

1908

Days

Metres per
second

Days

Metres per
second

Days

Metres per
second

January

4-9

10-3

14-4

February

6-6

13-2

15-1

March

4-4

8-0

8-5

April

5-4

9-4

10-7

May

5-3

10-0

11-6

June

4-6

10-3

9-6

July

4-3

8-4

10-8

August

5-4

8-6

10-1

September

5-3

10-3

13-6

October

5-3

9-8

- 11-5

November

5-6

9-5

12-4

December

4'2

8-2

10-6

Average

5-1

9-7

11-6

1909

January-

5-0

8-2

12-5

February

5-2

9-4

12-5

March

5-3

7'8

11-1

April

6-4

9-3

12-4

May

5-4

8-6

11-3

June

4-8

7'6

10-0

July

5-3

8-6

12-2

August

3-9

September^

7-4

9'5

October

5-6

9-0

12-1

November

4'5

8-8

12-5 .

December

6-3

10-1

137

Average

5-1

8-5

11-6

INTRODUCTION

Velocity of the Wind

1908

1909

335m.

500 m.

750m.

335m.

500 m.

750m.

January

1*
26

5
26

11
21

0
26

9
21

February

1
25

6
23

0
24

7
22

March

April

May

June

July

August

September

October

November

1
23

0
20

1
19

0
21

2
21

8
21

December

0
24

1
24

0
21

4
19

6
15

Total

297

276

219

296

289

264

* The numerator represents the number of days on which the velocity of
the wind reached 15 metres per second, and the denominator the number of
days on which readings were taken.

t Observations defective.

34 VEGETATION OF THE PEAK DISTRICT [CH.

The importance of wind velocity as regards vegetation is
that transpiration increases with the velocity of the wind. It
is not known whether the relation is in any degree precise, but
the general fact would appear to be incontestable. It will be
seen that there is a considerable increase in the velocity of the
wind as the higher altitudes are reached; and this fact, especially
when considered with the fact that the temperature decreases
at the higher altitudes, helps to explain, in no inconsiderable
degree, the paucity of the flora and the remarkable features of
the vegetation of the higher altitudes. It must be remembered,
also, that the peaty soil which characterizes nearly all the
higher summits of the district is usually regarded as being
physiologically dry ; and this, if the fact be so, further increases
the dangers of those plants which are exposed to excessive trans-
piration. The distribution of the days on which the velocity of
the wind reached 15 metres per second is shown on p. 33.

Humidity of the Atmosphere

Whilst the records for the two years indicate a mean
monthly humidity of the air of about 85 per cent., there are
remarkable fluctuations in the daily records which are inter-
esting when considered in relation to the conditions of plant
life. The important point, generally speaking, with regard to
atmospheric humidity, is that the lower the humidity the greater
the amount of evaporation or transpiration. Schimper (1903 : 4)
states that transpiration " constantly increases in proportion to
the dryness of the atmosphere." The daily records show that
the atmospheric humidity fluctuates considerably at the different
altitudes; and this variation is sometimes in the direction of
greater humidity at the higher altitudes and at other times in
the contrary direction. However, the lowest percentages occur
at the higher altitudes on the whole ; and, as plants, in order
to survive, must be adapted to the extreme conditions of their
habitats, it follows that plants at the higher altitudes are
disadvantageously situated not only as regards a lower tem-
perature and a greater wind velocity, but also, on the whole, as
regards a lower humidity of the atmosphere. Whether or
not this applies to altitudes much higher than 750 metres has
yet to be determined.

INTRODUCTION

At 335 metres

At 500 metres

At 750 metres

1908

Days

Per cent.

Days

Per cent.

Days

Per cent.

January

February

March

April

May

June

July

.— . 8D

August

September

October

November

December

Average

1909

January

February

March

April

May

June

July

August

September

October

November

December

Average

3—2

VEGETATION OF THE PEAK DISTRICT

[CH.

The lowest readings were registered on October 3rd, 1908,
and on January 28th, 1909, when the humidity fell so low as
25 per cent, at 750 m. The month of May, 1909, is interesting
on account of its low atmospheric humidity in this district.
The monthly average at the three altitudes of this month was
65 per cent.; and, at 500m., out of the 25 days on which
readings were taken, the humidity fell below 60 per cent, on
12 days. The number of days on which the atmospheric
humidity fell below 60 per cent., and the monthly distribution
of these days, are indicated below :

1908

1909

335 m.

500m.

750m.

335m.

500 m.

750m.

January

0*
24

0
26

2
21

February

0
25

1
25

1
19

2
24

March

0
23

1
23

1
.19

0
27

0
25

April

May

June

July

August

September

October

November

0
25

0
24

2
23

0
21

0
18

December

2
17

0
23

0
17

Total

7
293

12
283

274

17
293

22
271

25
263

* The numerator represents the number of days on which the atmospheric
humidity fell below 60 per cent., and the denominator the number of days on
which observations were taken.

I] INTRODUCTION 37

It will be seen that, whilst undertaken with* a different
object, the results of the observations on the upper atmosphere
by Professor Schuster and his staff have several important
bearings on vegetation, though the significance of these cannot
be correctly appraised until the observations have been con-
tinued for a considerable number of years. Though admittedly
incomplete, they still help to furnish clues as to the different
conditions under which vegetation lives at the different altitudes.

NOTE ON THE USE OP THE WORDS " ACIDIC " AND "BASIC." Geologists

have long distinguished between "acidic" and "basic" igneous rocks.
The former are poor, the latter rich in soluble mineral salts. From
the standpoint of the distribution of vegetation, the amount of soluble
mineral salts in the soil is a fundamental matter. Acidic rocks, soils,
peats, and waters are those which contain only a small amount of soluble
mineral salts ; and basic rocks, soils, peats, and waters are those which
contain a large amount. In time, when more analyses have been made,
it may be possible to express this relationship in quantitative terms ;
but, in the present state of knowledge, the matter can only be expressed
in a general way. Acidic waters are neutral to acid in reaction, basic
waters neutral to alkaline.

CHAPTER II

WOODLAND ASSOCIATIONS

Distribution of the woods. Woodland associations of Great Britain.
Woodland associations of the southern Pennines. Factors related
to the distribution of the woodland associations. Oak woods of
Quercus Robur. Transitional woods of Quercus Robur and Q. sessili-
Jlora. Oak woods of Quercus sessiliflora ; trees and shrubs ; variation
of vegetation in the oak woods ; influence of shade on the ground
vegetation. Alder- willow thickets. Birch woods of Betula pubescent ;
the primitive birch forest. Ash woods of Fraxinus excelsior ; semi-
natural woods and plantations on the limestone slopes ; trees and
shrubs ; herbaceous vegetation. Comparison of the woodland plants
of the southern Pennines.

DISTRIBUTION OF THE WOODS

THE great majority of the woods occur on the slopes of the
hills, where they ascend, on an average, to about 1000 feet
(305 m.). Occasionally, they reach an altitude of 1250 feet
(381 m.). On the Coal-measure rocks, which do not, as a rule,
reach so high an elevation as the Pendleside, Millstone Grit,
and Mountain Limestone rocks, the woods occasionally extend
on to the flatter plateaux. In such situations, woods seldom
occur at altitudes higher than 800 feet (244 m.). On the whole,
the woods are of small size ; and they by no means cover the
whole of the hill slopes. In fact, as a rule, the hill-sides are
occupied by uncultivated grassland (see Chapter IV) or scrub
(see Chapter III), where they are not cultivated as permanent
pasture (see Chapter VIII).

Figure 3.

H". B. Crumi>

Oak Wood of Quercus sessiliflora.

The trees, being near their upper altitudinal limit and the soil

being shallow, are small. The ground vegetation consists chiefly

of the Bilberry (Vaccinium Myrtillus) on and around the boulders,

and of the silver Hair-grass (Deschampsiajlexuosa).

QH. II] WOODLAND ASSOCIATIONS 39

WOODLAND ASSOCIATIONS OF GREAT BRITAIN

The various plant associations which are known to occur
among British woodlands are summarised below (cf. Moss,
Rankin, and Tansley, 1910):—

I. ALDER AND WILLOW ASSOCIATIONS. On very wet soils.

A. On soils supplied with acidic waters.

1. Alder and willow thickets of lowland moors.

B. On soils supplied with basic waters.

2. Alder and willow thickets of the East Anglian fens.

C. On fresh soils subject to periodical inundations.

3. Alder and willow thickets by stream sides.

II. OAK AND BIRCH ASSOCIATIONS. On non-calcareous soils.

D. On deep clays.

4. Oak woods with Quercus Robur ( = Q. pedunculata) dominant.

Usually coppiced (see Moss, Rankin, and Tansley, 1910 :
118). Widespread throughout the lowlands of southern
and central England.

4 b. Oak-hornbeam woods with Q. Robur and Carpinu* Betulus
sharing dominance. Rather local in south-eastern England.
Frequently coppiced.

E. On dry sands and gravels. Not uncommon in the south and

east of England. Locally coppiced.

5. Oak woods with Quercus Robur or Q. sessiliflora dominant,

either separately or in combination.

6. Birch woods with Betula pubescent dominant, or with B.

pubescens and B. alba (^B. verrucota) in combination.

7. Pine woods with Pinus sylvestris dominant.

7 a. Mixed woods of oaks, beeches, birches, and pines.

8. Beech woods with Fagus sylvatica dominant. Local in the

south of England.

F. On the shallow soils of the older siliceous rocks.

9. Oak woods with Q. sessiliftora dominant. Very common on

hill slopes in the north and west of Britain at altitudes
below 1000 feet (305 m.). Locally coppiced.

10. Oak-ash woods with Q. sessiliflora and Fraxinu* excelsior

sharing dominance. Very local. They occur in the Lake
District, where the rainfall is very high.

11. Birch woods with Betula pubescens dominant. Local. They

occur in the north of England as a zone above the woods
of Quercus sessiliflora at altitudes between 1000 feet and
1250 feet (381 m.). Much commoner in Scotland.

12. Birch-ash woods with B. pubescens and Fraxinus excelsior

sharing dominance. Local. They occur in the Lake
District.

40 VEGETATION OF THE PEAK DISTRICT [CH.

13. Birch-pine woods with B. alba; B, pubescens and Pinus

sylvestris var. scottica sharing dominance. Local and
confined to mid-Scotland.

14. Pine woods with Pinus sylvestris var. scottica dominant.

Local and confined to mid-Scotland.

III. ASH AND BEECH ASSOCIATIONS. On calcareous soils.
G. On deep marls or calcareous clays.

15. Ash-oak woods with Fraxinus excelsior and Quercus Robur

sharing dominance. Abundant in the south of England.
Usually coppiced.

H. On shallow calcareous soils on hill slopes of the fissured limestone
rocks.

16. Ash woods with Fraxinus excelsior dominant. Frequent in

the west and north of England up to about 1000 feet
(305 m.), and local on the chalk.

17. Ash-birch woods with Fraxinus excelsior and Betula pubescens

sharing dominance. Local on the upper slopes of hills of
Carboniferous Limestone in the north of England.

I. On shallow and very calcareous soils on chalk rock.

18. Beech woods with Fagus sylvatica dominant. Frequent on

the chalk escarpments in south-eastern England.

Of the woodland associations above enumerated, two are
well developed on the southern Pennines, and three others are
only moderately well represented. The two former are the
association of Quercus sessiliftora on damp, shallow, siliceous
soils, and the association of Fraxinus excelsior on shallow
calcareous soils ; and these woods are described in some detail
in this chapter. The woods which are only moderately well
represented on the southern Pennines are the association of
Quercus Robur on deep sandy soils, the association of Betula
pubescens on damp, shallow, siliceous soils, and the alder-willow
thickets of stream sides. Some transitional and intermediate
woods also occur, and these will be referred to in the proper places.

The relationships of these associations may be conveniently
set out in the following form : —

Alnus glutinosa and Salix spp. ALDER- WILLOW

dominant THICKETS

Quercus Robur dominant) _ . . ^ _

WOODS WITH •{ x> •/ •-, j • \ Oak woods OAK AND

Q. sessihfiora dominant I v „

» * } D- i J f BlRCH WOODS

Betula pubescens dominant Birch woods j
(Fraxinus excelsior dominant ASH WOODS

II] WOODLAND ASSOCIATIONS 41

The distinction between the oak and birch woods on the
one hand and the ash woods on the other hand is very sharp
and clear in the Peak District, where most of the woods
may without difficulty be referred to the oak and birch woods
or to the ash association. It is true that a number of the
woods are exploited for timber. However, in many of these, no
re-planting takes place; and the indigenous trees spring up
again quite spontaneously, either from the cut stools or from
self-sown seed. In other cases, non-indigenous trees, such as
beech (*Fagus sylvatica1), sycamore (*Acer Pseudoplatanus),
larch (*Larix detidua=*L.europaea), and pine (*Pinus sylvestris)
are planted where the native trees have been felled ; but, even
in these cases, unless the shade cast by the planted species
differs greatly from that cast by the original ones, the ground
flora usually affords a fairly conclusive test as to whether or
not the original wood belonged to the oak and birch woods or
to the ash wood. A few of the woods of the district may indeed
be said to be really primitive, as human interference with them
is confined to the occasional cutting down of one or two trees
by the occupier of some upland farm.

Many of the woods, however, are in a degenerate condition ;
and there is in this district no sharply dividing line between
degenerate woodland on the one hand and scrub (considered
in the next chapter) on the other. The questions relating to
existing plantations and to reafforestation are discussed in the
last chapter of the book.

FACTORS RELATED TO THE DISTRIBUTION OF THE
WOODLAND ASSOCIATIONS

Sufficient examples of woodland have now been examined in
this and other districts to enable one to judge, in a general way
at least, which are the principal ecological factors related to the
present distribution of the various woodland associations. The
oak and birch woods of the Pennines, as contrasted with the, ash
woods of the same region, are related to a difference in the
chemical nature of the soil; for the former woods are here
strictly confined to non-calcareous soils, and the latter, with

1 Throughout this book, the species which are not indigenous are preceded
by an asterisk.

42 VEGETATION OF THE PEAK DISTRICT [CH.

equal strictness, to calcareous soils. The associations of Quercus
sessiliflora and of Betula pubescens, as contrasted with the
association of Quercus Robur, are also edaphic associations ; for
the former occur solely on the shallow siliceous soils of the
sandstones and shales whilst the latter is limited to the deep
fluvio-glacial sands.

On the other hand, the association of Quercus sessiliflora, as
contrasted with that of Betula pubescens, is related to those
climatic factors connected with altitude; for both associations
occur on shallow siliceous soils, but the former occurs at
altitudes below 1000 feet (305 m.) and the latter at altitudes
between 1000 feet and 1250 feet (381 m.).

The mean annual rainfall of the sites of the various woodland
associations varies locally from about 35 inches (89 cm.) to about
50 inches (127 cm.); but, so far as one is able to judge, there
is, in this district, no definite relationship between the different
woodland associations and local differences in rainfall. On the
whole, it may perhaps be said that the woods of Quercus Robur
have the lowest rainfall and those of Betula pubescens the highest
rainfall ; whilst the rainfall of the woods of Quercus sessiliflora
and of JFraxinuB excelsior is intermediate and approximately
equal in amount.

As regards the water-content of the soils of the various
woods, that of the woods of Quercus Robur is the lowest, that
of the woods of Q. sessiliflora and Fraxinus excelsior is rather
higher, varying from moderately dry to very wet, and that of
the woods of Betula pubescens is, on the whole, the highest.
The surface soils of the birch association and of the two oak
associations show a marked tendency to form acidic humus, a
tendency which is scarcely discernible in the soils of the ash
woods. The nature of the surface soil is doubtless important
in relation to the germination of the seeds of the dominant
species, and therefore in relation to the rejuvenation of the
woods; but few or no experiments appear to have been con-
ducted with the view of testing such a hypothesis. In any
case, the surface soil cannot have much to do with the biology
of mature trees with deep tap roots, such as the ash.

Factors, then, which appear to be of importance in accounting
for the differential distribution of the various woodland associa-
tions of the Peak District are (1) the chemical nature of the

lyriglit • W. I). Cm

Figure 4.

Oak Wood of Quercus sessiliflora.

Shrubby undergrowth. Dog Rose (Rosa canina) in fore-
ground and Hazel (Corylns -Avellana) behind.

Il] WOODLAND ASSOCIATIONS 43

soil, (2) the depth of the soil, and (3) the altitude of the
woodland site. Other factors are of importance with regard
to the distribution of the various types of ground vegetation
(see pp. 53 and 71).

1. The chemical nature of the soil. The soils of the
slopes of the limestone hills, to which the ash woods are
limited, are rich in calcium carbonate: on newly exposed
soils in such situations, the soil, in fact, may consist almost
wholly of this substance ; but commonly the percentage of lime
varies from about five to about thirty per cent. The percentage
of lime must be very high in the rock-strata in which the tap
roots of the ash are fixed. On the chalk of the south-east of
England, the woods are usually dominated by the beech (Fagus
sylvatica), though the ash association does occur to some extent
on the chalk.

The soils of the sandstones and shales have a very low
lime-content. In several analyses, the percentage of lime
(calculated as calcium oxide) was so low as 0'02 per cent. ; and
in no case was it higher than 0'05 per cent. On these soils,
ash woods do not occur, whereas oak and birch associations are
numerous and typical. It is not suggested here that the presence
of lime is the direct cause of the occurrence of ash woods on the
limestone slopes, or that the absence of it is the direct cause of
the occurrence of oak and birch woods on the siliceous slopes, as
much more experimental work must be done by plant physio-
logists before this classical problem can be approached from a
point of view which is likely to afford a satisfactory outlook on
the problems involved : all that is stated is that, so far as this
district is concerned, the ash woods invariably occur on the
calcareous strata and never elsewhere, and that the oak and
birch woods invariably occur on the siliceous rocks and never
on the calcareous ones. It seems, however, reasonable to suggest
that the presence or absence of a high lime-content of the soil
is concerned either directly or indirectly with the present distri-
bution of the principal types of woodland of this district. /

2. The depth of the soil. The fluvio-glacial sands in
the west of the district are deep, and hence offer no physical
obstacle to the growth of the long tap roots of Qiwrcus Robur.
Woods of Quercus Robur occur on these soils. Further, so far as
this district is concerned, such woods are restricted to these soils.

44 VEGETATION OF THE PEAK DISTRICT [CH.

The woods of Quercus sessiliflora and of Betula pubescens
are confined to the sandstones and shales. The soil over the
sandstones is shallow, that is, shallower than would appear to
be necessary for the free growth of the tap roots of Quercus
Robur ; and similarly the soil of the shales is frequently shallow,
being often interrupted by bands of flagstone and half-formed
sandstone. The restriction of woods of Quercus sessiliflora to
shallow, siliceous soils is very general throughout the whole of
the British Isles; but exceptional cases occur on sandy and
gravelly soils in the south-east of England.

3. The altitude of the woodland site. Woods of
Quercus sessiliflora cease at altitudes of about 1000 feet (305 m.),
whilst woods of Betula pubescens reach altitudes of about
1250 feet (381 m.). As the physical and chemical conditions
of the soils of the two associations are identical, it seems
clear that the failure of the oak woods to reach the higher
altitude is due to the severer climatic conditions which prevail
there. Such conditions are the lower temperatures, the greater
velocity of the wind, and (to some extent) the lower atmo-
spheric humidity and higher rainfall.

OAK WOODS OF QUERCUS ROBUR

In this district, woods of the peduncled oak (Quercus Robur)
occur only on the western boundary; and they represent the
eastern fringe of the lowland oak woods of the Cheshire plain.
The latter, in their turn, are a north-western continuation of
the lowland oak woods which are characteristic of the Midlands
and of the south of England ; and an eastern extension of the
latter may be traced through Nottinghamshire and into east
Yorkshire. As already indicated, oak woods of Quercus Robur
may occur either on deep clays or on deep sands or gravels.
Woods of both these types occur on the Cheshire plain, though
the oak woods of the sandy and gravelly soils are there more
extensive than those on clayey soils. It is the woods of the
former type that just reach the western margin of this district.

The best examples of woods of Quercus Robur in this
district occur in the lower courses of the rivers Etherow and
Goyt, two of the head-streams of the river Mersey. Ernocroft
Wood and Bottoms Hall Wood are examples of such woods,

II] WOODLAND ASSOCIATIONS 45

where Quercus Robur is the dominant tree and where Q. sessili-
flora is rare. The whole of this area has been mapped by the
geological surveyors as consisting of rocks of the Coal-measure
series ; but such rocks are here obscured, or partially obscured,
by deep deposits of fluvio-glacial sands. There are, unfortu-
nately, no geological maps with drift published of any portion
of the district ; and, in fact, the Geological Survey has not yet
commenced its examination of the drift of this locality. When,
however, such maps are published and compared with vegetation
maps, they will afford a striking commentary on the differential
distribution of the woods of Quercus Robur and Q. sessiliflora on
the west of the Pennines in this latitude.

The region of woods of Quercus Robur of the lowlands of
the east of the Pennines does not reach the Peak District, and,
in fact, possibly ceases east of Sheffield.

The woods of Quercus Robur of this district occur at their
local, upper altitudinal limit, and have been interfered with by
the planting of foreign trees and shrubs, such as laurels and
rhododendrons; and they cannot therefore be regarded as
typical of such woods in general. Hence it is not desirable to
describe them here in detail. Such a description will be a more
fitting outcome of a vegetation survey of some portion of the
Cheshire plain, where woods of Quercus Robur are more extensive,
more numerous, and more typical in character.

TRANSITIONAL WOODS OF QUERCUS ROBUR AND
Q. SESSILIFLORA

In a few places near the junction of the woods of Quercus
Robur and of Q. sessiliftora, some small woods occur in which
the two species are found side by side. This is the case,
for example, with regard to the small Townscliffe Wood,
east of Mellor. Had such woods been extensive enough, their
transitional character could have been indicated on the vegetation
maps by giving them the ground colour of the woods of Quercus
Robur and stippling on this the darker colour used for woods of
Q. sessiliflora. However, this course was impracticable owing
to the small size of the transitional woods.

Whilst Quercus Robur and Q. sessiliflora respectively form,
as a rule, well-defined associations, it sometimes happens that a

46 VEGETATION OF THE PEAK DISTRICT [CH.

stable association occurs in which the two species are present
in almost equal proportions. Such transitional woods may
occur in localities where the two associations come into close
propinquity, and also sometimes on dry sandy or gravelly
soils. In such transitional woods, the hybrid oak (Quercus
Robur x sessiliflora) invariably occurs. The occurrence of this
hybrid, though quite general in such situations, was unsuspected,
so far as this country is concerned, until quite recently (see
Moss, 1910 a: 34).

OAK WOODS OF QUERCUS SESSILIFLORA

Woods of Quercus sessiliflora occur on the damp, shallow,
siliceous soils of the Coal-measures, the Millstone Grit, and the
Pendleside (or Yoredale) rocks, up to an altitude of about
1000 feet (305 m.). The rocks of the Coal-measure series, as
a rule, occur at moderately low altitudes, flanking the Pennine
watershed. On these rocks, the woods, whilst mainly confined
to the slopes of the hills, occasionally extend some little distance
on to the plateaux, whereas on the rocks of the Millstone Grit
and the Pendleside series, the woods are almost entirely confined
to the steep slopes of the narrow valleys or " cloughs " ; and it
is only rarely that they spread out on to the flatter and more
exposed plateaux.

The woods of Quercus sessiliflora of the southern Pennines
have been described by previous writers. Crump (1904: xxxiii)
subdivided them into (a) mixed deciduous woods, and (6) dry
oak woods on the Coal-measure, Millstone Grit, and Yoredale
(or Pendleside) rocks. Smith and Moss (1903 : 387) and Smith
and Rankin (1903 : 159) adopted almost the same subdivisions
when they described (a) lowland oak woods and (6) upland
oak woods. Woodhead (1906), in describing their ground
vegetation, referred to them as (a) mixed deciduous woods
of the Coal-measure area (p. 336), and (6) mixed deciduous
woods of the Millstone Grit area (p. 347). However, all these
subdivisions are only particular aspects of the association of
Quercus sessiliflora as developed on shallow, siliceous soils.
The " pine woods " of Smith and Rankin (loc. cit.) are merely
plantations of conifers, on sites previously occupied by woodland,
grassland, or farmland.

Coptjriijlit

JF.fB. Cnunii

Figure 5.

Oak Wood of Quercus sessiliflora.
The ground vegetation is composed largely of the Bluebell (Scilla non-scripta).

II] WOODLAND ASSOCIATIONS 47

Trees and Shrubs

The sessile-fruited oak (Quercus sessiliftora) is undisput-
ably the prevailing tree of these woods. Because of the com-
paratively great amount of light which penetrates the oak
canopy, the ground is fully covered by vegetation ; and therefore
the tree may be spoken of as the dominant species, as it exercises
a controlling influence on the rest of the vegetation of the wood.
In the earlier accounts (op. cit.) of the vegetation of the Pennines,
the plant was referred to as " Quercus Robur Linn." It has,
however, been shown (Moss, 1910 a) that this name refers to
the peduncled oak alone, and that it is possible and desirable
to distinguish separate associations of the two British species
(Q. Robur and Q. sessiliftora) of oak. In this district, Quercus
sessiliftora grows well and forms moderately large trees up
to an altitude of about 800 feet (244 m.), particularly on the
shales : above this altitude, especially on soils over the massive
sandstone rocks, the trees are apt to be of short stature and
of small girth ; and near the present altitudinal limit of wood-
land, the trees are often little bigger than shrubs (see figure 3).
Seedlings are often met with in the damper woods, but are rare
in those with a peaty soil at the higher altitudes.

The pedunculate oak (* Quercus Robur) is absent from the
great majority of the oak woods of the Pennine slopes. As has
been already stated, this species is found in a few of the western
woods situated on the glacial sands : elsewhere in the district it
only occurs as a planted tree, along with other aliens, such as
the sycamore, the beech, the larch, and the pine. It is present,
as might be expected, in most of the newer plantations and in
park-lands; but, even in such localities, it is not very abundant,
and it rarely grows to a large size.

No conifers are indigenous in the woods of Quercus sessili-
flora of this district; but the Scots pine (*Pinus sylvestris)
and the larch (*Larix decidua) are frequently planted. Other
conifers occasionally or rarely met with in the woods are the
black or Austrian pine (*Pinus austriaca), the spruce fir (* Abies
excelsa), and the Douglas fir (*Pseudotsuga Douglasii).

As sub-fossil timber, the Scots pine is occasionally found
buried under the peat of the southern Pennines; and it is

48 VEGETATION OF THE PEAK DISTRICT [CH.

rather remarkable therefore that the plant is not indigenous in
the Pennine woods at the present time. Still, judging from
the paucity of the number of the records of buried pine
timber, the species does not appear to have been more than
an occasional or, at most, a locally abundant integer even
in the prehistoric woods of the Pennines; and it probably
became extinct at a very remote date. At the present time,
seedling pines are not abundant on the Pennines even in and
around pine plantations ; and the tree does not flourish nearly
so well on these hills as on the dry and sandy heaths in the
south of England.

The only species of poplar which is indigenous in this
district is the aspen (Populus tremula); and even this species
appears to be quite rare in the oak and birch woods. Other
poplars (e.g., *P. canadensis and *P. candicans) are planted
occasionally, though more frequently on the outskirts of the
woods than inside the woods themselves.

Several indigenous species of willow occur. Salix cinerea
is common, and ascends to nearly 1200 feet (366 m.) in some of
the cloughs. 8. caprea is occasional ; but both S. cinerea and
S. caprea are absent from the driest woods. 8. aurita is local,
but occasionally forms thickets in damp spots in the cloughs.
S. pentandra is also rare. Hybrids of S. caprea, S. cinerea,
and S. aurita are not uncommon. S. repens occurs, but is
rare. S. fragilis, 8. viminalis, 8. caprea x viminalis occur
locally by the stream sides, at altitudes below 600 feet
(183 m.). Although 8. alba, S. purpurea, and x S. rubra
(=8. purpurea x viminalis) are recorded (Linton, 1903), they
are perhaps not indigenous in the Peak District.

The hazel (Corylus Avellana) is rather abundant in the
damper woods, but much rarer in the drier ones.

The common birch (Betula pubescens) is, on the whole, the
most constant and the most abundant associate of the sessile
oak. Forms or varieties with glabrous or sub-glabrous twigs
(B. pubescens forma denudata) are not uncommon: B. pubescens
var. parvifolia is rare, but has been observed. In some of the
woods, however, the birch is rare or absent. Not infrequently,
the birch becomes locally dominant in places where extensive
felling of the oak and no subsequent planting, have taken
place ; and its small, light, and winged fruits are evidently of

II] WOODLAND ASSOCIATIONS 49

more advantage in colonizing cleared or partially cleared areas
than the large and heavy fruits of the oak. In some such places,
seedlings of the birch are extremely abundant ; and local plant
societies of well-grown birches are common in many of the oak
woods. A birch wood at low altitudes in this district usually
represents a degenerate oak wood which has been colonized by
birches. In ascending the cloughs, many of which are now
almost treeless, isolated plants of the common birch are often
the last trees which are encountered. Under the peat of the
moors, birch remains are locally very abundant.

The white birch (*Betula alba) is perhaps not indigenous
in the hilly woods of the Peak District, as it only seems to
occur in the company of such obviously planted trees as the
beech, sycamore, peduncled oak, larch and pine. It is never
abundant ; and it is absent over extensive tracts and from the
more primitive and the more upland woods.

The alder (Alnus glutinosa) is confined to stream sides
and marshy places, where it often forms small societies. It is
more abundant in the oak woods than in the ash woods.

The beech (*Fagus sylvatica), although an almost invariable
constituent of the larger woods, has little claim to rank as
indigenous. As a rule, evidences of its introduction are easy
to trace, either because it occurs in obviously recent plantations
or because historical evidence of planting is procurable.
Whether indigenous or not, the beech grows well on all the
Pennine slopes, both siliceous and calcareous. In favourable
seasons, ripe fruits have been observed on trees at an altitude
of 1500 feet (457 m.). First-year seedlings are frequently met
with in the woods: older seedlings, however, have not been
observed; and there is no evidence to show that the beech
rejuvenates itself in these hilly woods. Apparently the seed-
lings of the beech are all destroyed during their first winter,
perhaps because they are unable to endure the alternating cold
and mild periods characteristic of the markedly insular climate
of the north and west of the British Isles. On the other hand,
the rejuvenation of the beech may be observed on sandy and
on chalky soils in the south of England, where the tree is
indigenous. The analogy of the beech to the pine in the
matter of rejuvenation in the north and south of England is
remarkable; and it may be that the pine, as well as the

60 VEGETATION OF THE PEAK DISTRICT [CH.

beech, is indigenous in the south-east of England. As a
planted tree, the beech is locally abundant up to about
1600 feet (488 m.).

The Spanish or sweet chestnut (*Castanea sativa — *C.
vulgaris = *C. vesca) is planted rarely up to 1500 feet (457 m.) ;
but it is seldom a success in this hilly district ; and its fruits do
not ripen on the Pennines. In some of the lowland oak woods
of Cheshire, as in Delamere Forest, the tree is much more
successful ; and the tree is said to ripen its fruits occasionally
in one or two localities of that county. On sandy soils in
the south and east of England, the tree not uncommonly ripens
its fruits, as in Kent, Bedfordshire, and Cambridgeshire ; and
there young trees and seedlings may be seen in all stages of
development in certain woods and plantations.

The wych elm (Ulmus glabra = U. montana) is indigenous,
and occurs up to about 1000 feet (305 m.). Above this altitude,
it is frequent in plantations up to 1500 feet (457 m.). It is
a constant and sometimes an abundant constituent in the
damper woods, but is rare in the drier ones. In favourable
localities, seedlings are very common. The seeds germinate
very shortly after they fall from the tree ; and seedlings may
be found in August on damp, bare soil in sheltered situations.

The hawthorn (Grataegus Oxyacantha = Q. monogyna) is
an occasional associate in the damper and more shady woods,
and an abundant one in the drier and more exposed woods.
Frequently, it is the last relic of pre-existing woods on exposed
hill-sides. The form or variety laviniata is common ; and this
indeed may be the indigenous form.

The crab apple (Pyrus Malus) is never more than a shrub
on the hills of northern England. The remark in Lin ton's
flora (1903 : 142) that it is "common everywhere" in Derbyshire
is a curious over-statement. In the woods of Quercus sessili-
flora the plant is rather local, and rarely, if ever, abundant.
In many seasons, it fails to ripen its fruits.

The rowan or mountain ash (Pyrus Aucuparia) occurs in
most of the woods ; and, in rocky, upland, and heathy situations,
it is often abundant. It is frequently the last isolated tree
seen in ascending the cloughs.

The raspberry (Rubus Idaeus) is abundant locally, pre-
ferring damp soils without much acidic humus. R. fissus

W. B. Crump

Figure 6.

Oak Wood of Quercus sessiliflora.

The ground vegetation consists chiefly of the Bracken (Pterin
aquilina) and the wood Soft-grass (Holcm mollis).

II] WOODLAND ASSOCIATIONS 51

occasionally occurs in similar situations. The bramble or
blackberry is very abundant, " Rubus Selmeri and Rubus
dasyphyllus reaching the highest altitude" (Linton, 1903: 114)
of any of the segregates of this polymorphous group. The
dewberry (R. caesius) is confined to the lower altitudes,
where it is rather local.

Briers or wild roses (Rosa spp.) are common and generally
distributed, especially R. canina. R. tomentosa is local; and
" R. mollis " has been recorded. R. arvensis is locally abundant
at the lower altitudes. Other species of Rosa and Rubus are
enumerated at the end of the chapter.

Sloe or blackthorn (Prunus spinosa) is a constant, though,
as a rule, an infrequent member of the association. Rarely,
as by the stream sides in some of the cloughs, it forms dense
thickets. It rarely ripens its fruits at altitudes greater than
600 feet (183 in.). Bird-cherry (Primus Padus) is abundant
in some of the cloughs; but it becomes more and more un-
common as the plains are approached. Conversely, the cherry
(Prunus avium) is commoner at the lower levels, and fails to
ascend higher than about 600 feet (183 m.).

Gorse or furze (Ulex europaeus) is thinly scattered through
the woods at the lower altitudes; and the dwarf furze (Ulex
Oallii) is often abundant on the outskirts of the woods at the
higher altitudes.

Broom (Cytisus scoparius) is found but rarely inside the
woods; but, like the two species of Ulex, it is often abundant
on the outskirts of the woods.

The holly (Ilex Aquifolium) occurs in almost every oak
wood of the district, and is typically abundant where the soil
is moderately dry. It is occasionally the last isolated tree seen
in ascending the cloughs. Linton (1903: 97) records it as
occurring at an altitude of 1050 feet (318 m.) in Jagger's
Clough. The plant rarely produces flowers, and still more
rarely produces ripe fruit at the higher altitudes on the
Pennines.

The maple (Acer campestre), as a shrub, is confined to com-
paratively low altitudes, and is not encountered at all in the
higher and remoter cloughs. As a tree, it is almost if not
quite unknown in the woods of the district. The sycamore
(* Acer Pseudoplatanus) is always an introduction, though, as

52 VEGETATION OF THE PEAK DISTRICT [CH.

a planted tree, it is locally abundant and succeeds well. First-
year seedlings of sycamore are common ; and occasionally these
grow up into trees.

No species of lime is indigenous in the oak and birch woods
with the possible exception of the small-leaved species (Tilia
cordata = T. ulmifolia = T. parviflora) ; and even this is ex-
tremely rare. The common lime (T. europaea=T. vulgaris)
is never a woodland plant; and the broad-leaved lime
(T. platyphylla = T. grandifolia) is not indigenous in Derby-
shire.

Ivy (Hedera Helix) is a constant and frequent associate in
all the woods.

The ling or heather (Calluna vulgaris) is confined to
woods whose soil contains much acidic humus or peat, and
to the more open parts of such woods.

The bilberry (Vaccinium Myrtillus) occurs in somewhat
similar situations to the heather, and usually grows with it ; but
it also thrives in more shady parts of the wood than that plant
(see figure 7). The cowberry (V. Vitis-idaea) is local, but
very abundant in some degenerate woods with a peaty soil,
as in Longdendale, near Crowden railway station.

The ash (Fraxinus excelsior) is, in the oak woods, almost
limited to stream sides and swampy places. In the drier oak
woods it is very rare.

The elder (Sambucus nigra) is locally abundant in the
lower woods, but rather uncommon at the higher altitudes.
In places where the woods are disturbed and especially near
villages, the plant frequently overruns the ground.

The guelder rose (Viburnum Opulus) is, in all the damper
woods, an occasional associate, and reaches comparatively high
altitudes (about 318 m.).

The honeysuckle (Lonicera Periclymenum) is abundant
and general. This plant and the ivy are the only indigenous
lianes of the north of England.

II] WOODLAND ASSOCIATIONS 53

Variation of Vegetation in the Oak Woods

The vegetation of the oak woods varies greatly from place
to place. The variation in the vegetation is due to the varia-
tion of the various ecological factors. It is impossible, in the
present state of knowledge, to give anything like a complete
account of these factors ; and it is still more difficult to state
the action of the various factors either on the vegetation as a
whole or upon the individual plants. However, some operating
factors may be recognised ; and doubtless future work by plant
physiologists will suggest what are the effects of these factors
on the vegetation and on the individual plants.

In the woods of Quercus sessiliftora, important ecological
factors are the water-content of the soil, the kind and quantity
of humus present, and the amount of light which penetrates
the leaf-canopy of the trees and shrubs. These factors are cor-
related in the most complex manner, and can perhaps best be
illustrated by considering various woodland habitats where any
one of them becomes pronounced. It must be remembered,
however, that the habitats chosen are connected by all possible
intermediate stages ; and it is the sum of these minor habitats
which constitute the more general habitat of the association
as a whole.

(1) Marshy places. Where springs arise and by the
sides of the various rills and streams, wet and marshy places
occur where the soil is well aerated; and consequently any
humus that is present is mild (not alkaline) humus and not
acidic humus. In such places, the oak (Quercus sessiliftora)
tends to become very rare, and the alder (Alnus glutinosd)
and the ash (Fraxinus excelsior) to become correspondingly
more abundant. Birches (Betula pubescens, and B. pubescens
var. parvifolia) may however remain. At the lower altitudes,
the crack willow (Salix fragilis) is sometimes found ; and at
the higher altitudes, where, however, the soil-water may be
more or less acid, Salix aurita is locally abundant. 8. cinerea
is usually an abundant species ; and where the two last are
found together, hybrids (8. aurita x cinerea) occur. The bird

54 VEGETATION OF THE PEAK DISTRICT [CH.

cherry (Prunus Padus) is locally abundant. The ground flora
is often characterised by tufts of the common rush (Juncus
effusus); and a smaller species of rush (J. lamprocarpus) is
often strongly in evidence. Many marsh plants occur, such as
the meadow sweet (Spiraea Ulmaria) and the great Valerian
(Valeriana sambucifolia). Ferns are abundant, particularly
the lady fern (Athyrium Filix-foemina), and also the wood
horsetail (Equisetum sylvaticum and E. sylvaticum var. capil-
lare). Almost any of the plants which ordinarily occur in a
Juncus swamp (see page 147) may be found; whilst the
following additional species, although very characteristic, are
more or less local in their occurrence: —

Phegopteris Dryopteris (rare) Lysimachia vulgaris

P. polypodioides (local) Myosotis palustris

Nephrodium montanum Mentha aquatica

( = N. Oreopteris) Solanum Dulcamara

Athyrium Filix-foemina Scrophularia nodosa

A. Filix-foemina var. rhoeticum Valeriana dioica (rare)

Eumex Acetosa V. sambucifolia

Stellaria nemonim (local) Petasites ovatus

Trollius europaeus (rare) Cnicus palustris

Ranunculus Ficaria C. heterophyllus (rare)

Cardanaine amara (local) Crepis paludosa (local)

C. flexuosa Deschampsia caespitosa

Chrysosplenium oppositifolium Carex remota (rare)

C. alternifolium (local) C. pendula (rare)

Spiraea Ulmaria C. sylvatica (rare)

Geum rivale C. helodes
Q. rivale x urbanum (rare) ( = C. laevigata)

Geranium sylvaticum (rare) Luzula maxima

Angelica sylvestris Juncus effusus

(2) Damp places with mild humus. It is in these
places that one finds the most characteristic " woodland
plants " ; but, in a hilly district like this, shade-loving species
and their typical habitat are much more local in occurrence
than in lowland woods. Here they occur, as a rule, on moderate
and well-drained slopes, usually near streams, and where the
light is not too strong. The oak is the dominant tree: the
wych elm occurs rather abundantly, and the wild cherry (Prunus
Cerasus and P. avium) rather rarely. Birches and holly are
typically absent. Shrubs are moderately abundant, especially

Figure 7.

W. B.

Oak Wood of Quercus sessilifiora.

The ground vegetation consists largely of the Bracken (Pteris
aquilina), the Bilberry (Vaccinium Myrtillus), and the silver Hair-
grass (Deschampsia fiexuosa).

WOODLAND ASSOCIATIONS

hazel, sallows, maple, wild roses, ivy, and honeysuckle,
following herbaceous species are characteristic: —

The

Nephrodium Filix-mas
N. spinulosum
N. dilatatum

Aspidium aculeatum (rare)
A. angulare (rare)
Athyriutn Filii-foemina
Rumex Acetosa
Lychnis dioica

( = Melandrium rubrum)
Stellaria Holostea
Aquilegia vulgaris (v. rare)
Anemone nemorosa
"Ranunculus auricomus
Fragaria vesca
Geum urbanum
Vicia sepium
V. sylvatica (v. rare)
Geranium Robertianum
Oxalis Acetosella
Mercurialis perennis
Viola Riviniana, var.
Epilobium montanum
Circaea lutetiana
Sanicula europaea
Conopodium majus
Heracleum Sphondylium
Primula vulgaris (rare)

Myosotis sylvatica (local)

Ajuga reptans

Prunella vulgaris

Lamium Galeobdolon

Stachys sylvatica

Veronica montana

Asperula odorata

Campanula latifolia (rare)

Lactuca muralis (local)

Hieracium vulgatum (local)

H. boreale (local)

Milium efiusum (local)

Poa nemoralis (rare)

Melica uniflora

Festuca gigantea

Bromus ramosus

Arum maculatum

Allium ursinum

Scilla non-scripta

Paris quadrifolia (v. rare)

Gagea lutea (v. rare)

Narcissus Pseudo-Narcissus (local)

Tamus com munis

Neottia Nidus-avis (v. rare)

Listera ovata (local)

Helleborine latifolia (rare)

Orchis mascula (local)

(3) Dry places with some acidic humus in the
upper layers of the soil. The oak is dominant: birches
and holly are usually present : the wych elm tends to be
uncommon or rare : shrubs, such as hazel and Salix capraea,
are fairly abundant : ivy, honeysuckle, roses, and brambles
tend to be abundant. The ground species with showy
flowers are of local occurrence, except the bluebell which is
often very abundant, growing in great masses (see figure 5),
especially if the soil is not too dry. The typical ground
vegetation is that described by Woodhead (1906 : 344) as a
" meso-Pteridetum," in which the bracken (Pteris aquilina),
the bluebell (Scilla non-scripta), and the wood soft-grass (Holcus
mollis) occur as social plants (see figure 6). The shade cast
by the trees and shrubs is less than in the preceding type of

56 VEGETATION OF THE PEAK DISTRICT [CH.

ground vegetation. The following ground species may also
be expected to occur: —

Nephrodium dilatatum Digitalis purpurea

N. Filix-mas (local) Galium saxatile

Pteris aquilina Campanula rotundifolia

Rumex Acetosella Hieracium boreale

Potentilla erecta (local) Holcus mollis

Arenaria trinervia Deschampsia flexuosa (local)

Polygala serpyllacea Anthoxanthum odoratum

Viola Eiviniana var. diversa Poa trivialis (local)

Conopodium majus Carex pilulifera (local)

Teucrium Scorodonia Luzula pilosa

Lamium Galeobdolon Scilla non-scripta

(4) Places where acidic humus is present in good
quantity. The oak remains dominant: the birch and the
mountain ash are often abundant : the wych elm and the
ash are rare or absent : shrubs are rather rare and sometimes
almost absent; whilst heathy dwarf shrubs, especially the
bilberry, are typically abundant (see figures 3 and 7). Ground
species with showy flowers are rare : the soft-grass (Holcus
mollis) is local and often absent ; but the silver hair-grass (Des-
champsia flexuosa} becomes exceedingly abundant : the bracken
varies from being very abundant to very rare. This type of
vegetation was termed by Woodhead (1906 : 347) a " xero-
Pteridetum." It is characterized by the following species: —

Nephrodium dilatatum Digitalis purpurea

Blechnum spicant Melampyrum pratense

Pteris aquilina var. montanum

Potentilla erecta var. hians

Ulex Gallii (local) Galium saxatile

Cytisus scoparius (local) Solidago Virgaurea

Lathyrus montanus Hieracium vulgatum (local)

Polygala serpyllacea Holcus mollis (local)

Pyrola media (v. rare) Deschampsia flexuosa

P. minor (rare) Molinia caerulea (local)

Calluna vulgaris Carex binervis

Vaccinium Myrtillus C. pilulifera

V. Vitis-idaea (local) Luzula pilosa

Teucrium Scorodonia L. multiflora

The two last-mentioned types of ground vegetation occupy
by far the major portion of the woodland area, and they have

II] WOODLAND ASSOCIATIONS 57

been described in some detail by Woodhead (1906 : 336, et seq.}.
In the case of a particular wood near Huddersfield, Woodhead
showed by means of sketch maps that under trees like the
oak and the birch, which admit a large amount of light, the
bracken flourishes; but under trees with a much closer
canopy, such as the wych elm, sycamore [introduced], and
beech [introduced], much light is cut off, and the bracken is
almost or entirely absent. Woodhead applied the same method
to another plant, the bluebell (Scilla non-scripta), in the same
wood. In this case, he found that light is not the [only]
controlling factor, but that the plant is most abundant in a
lighter, loamy soil where more shade occurred. The bluebell
also occurs in stiffer soils simulating clay, and here competes
with the yellow dead-nettle (Lamium Galeobdolon), the dog's
mercury (Mercurialis perennis), the cuckoo-pint (Arum macu-
latum), and numerous root-branches of small trees. In shallow,
sandy soil mixed with humus, the bluebell only occurs in
straggling patches. On such soils, the bluebell does not
form those unbroken stretches so characteristic of moist areas
(cf. figure 5). The grassy vegetation of many of these woods
is mainly composed of Holcus mollis and Deschampsia flexuosa.
The latter species prefers an acidic, humous soil, where it is
associated with Galium saxatile, Vaccinium Myrtillus, Teucrium
Scwodonia, and Solidago Virgaurea.

The plant society in which the bracken (Pteris aquilina) is
associated with Holcus mollis, Woodhead (loc. cit,) termed a
" meso-Pteridetum," and that in which the bracken is associated
with Deschampsia flexuosa he termed a " xero-Pteridetum."
These terms, however, are not very satisfactory. First, the
terms imply that the water-content of the so-called meso-
Pteridetum is higher than that of the so-called xero-Pteridetum;
but this is not established. Secondly, they imply that the
members of the former association are " mesophytes " and those
of the latter association " xerophytes " ; but many characteristic
members of the xero-Pteridetum can scarcely be admitted
to the " ecological class " of xerophytes. Lastly, it is question-
able if Schouw's termination -etum should be applied to any
vegetation unit other than a plant association ; and it is
doubtful if the plant communities in question should be given
a higher rank than that of ground societies.

58 VEGETATION OF THE PEAK DISTRICT [CH.

Influence of Shade on the Ground Vegetation

There are practically no places within the oak woods where
the shade is too great for the growth of a carpet of vegetation ;
but where the beech (*Fagus sylvatica) has been introduced
and planted in mass or even only in patches, such places occur.
Where the shade is most dense under the beeches, practically
no plants are to be found except a few mosses, and in autumn
some of the larger fungi. Where the shade is less dense, a few
grasses, such as Holcus mollis and Deschampsia flexuosa, may be
scattered about ; and mixed with them are a few shade-loving
species, such as dog's mercury (Mercurialis perennis) and wood
sanicle (Sanicula europaea).

The sycamore (*Acer Pseudoplatanus) also casts much shade ;
but, as this is usually introduced singly among the indigenous
oaks, the tree does not usually bring about a great change in
the ground vegetation.

The pine (*Pinus sylvestris) is frequently planted in mass ;
and, when planted closely, much shade is thrown, and the
original ground species tend to disappear.

Of indigenous trees, the wych elm ( U. glabra — U. montana)
casts the greatest shade ; but on the siliceous soils this species
does not usually occur as a social tree except where planted.

ALDER-WILLOW THICKETS

In some of the valleys, there is, at the present time, no
extensive tract of woodland at all. This is the case, for
example, in the Edale Valley and around Chapel-en-le-Frith.
There can be little doubt that, in all such cases, the primaeval
woodland has been destroyed and the land put under cultivation.
Trees, however, often line the banks of the streams which flow
through such localities, and form narrow fringing thickets which
may be a mile or so in length. The most abundant trees are
the alder (Alnus glutinosa), willows (e.g. Salix fragilis and
8. cinerea), and the ash (Fraxinus excelsior). These alder- willow
thickets are to be regarded as the persisting and lingering
remains of the alder-willow association which doubtless fringed
practically all the streams when the latter flowed through the

II] WOODLAND ASSOCIATIONS 59

primaeval oak (Quercus sessiliflora} forest. On the accompanying
vegetation maps, they are given the same colour as the oak
woods of which they originally formed a part.

Most of the alder-willow thickets occur on the Pendleside
shales; and on these soils at the lower altitudes, woods are
now rare. It seems highly probable that this is due to the
fact that the shales make excellent agricultural land ; and the
original woods on the shales, therefore, have nearly all been
felled, and the land put down to cultivation, chiefly as permanent
pasture (see Chapter VIII).

The flora of the alder-willow thickets does not differ
materially from that of the damper parts of the oak woods.
Occurring in the cultivated area, it is natural to find in them
some alien trees, and some invading pasture species among the
ground flora. The following trees and shrubs were noted in
the ash-alder thickets near Edale and Castleton : —

Subdominant species

Salix fragilis Alnus glutinosa

S. cinerea Fraxinus excelsior

Locally abundant species

Salix caprea Rubus spp.

Corylus Avellana Rosa tomentosa (rare)

Betula pubescens R. canina

Ulmus glabra Pyrus Aucuparia

( = TJ. montana) Hedera Helix

Prunus spinosa Lonicera Periclymenum

Occasional and rare species

*Larix decidua Q. sessiliflora

*Populus canadensis *Prunus insititia

*Castanea sativa Rosa arvensis

*Quercus Robur *Acer Pseudoplatanus

BIRCH WOODS OF BETULA PUBESCENS

Birch woods were recognized in Scotland by Robert Smith
(1900, a and 6) who stated that they were quite natural and
self-sown. Smith did not state which of the two British species
form the dominant element; but both are actually abundant

60 VEGETATION OF THE PEAK DISTRICT [CH.

in Perthshire, though Betula pubescens ascends to higher
altitudes than B. alba. In the Leeds and Halifax district, which
lies immediately to the north of the Peak District, " the birch
wood or uppermost tree zone of the Scottish Highlands is
represented by a modification of the oak wood.... The oak
[Quercus sessiliflora\ is usually dominant; but when the best
of these are removed and no others planted, the birch [Betula
pubescens] becomes dominant, either alone or with stunted
oaks" (Smith and Moss, 1903: 388). In the Harrogate and
Skipton district of the mid-Pennines, an uppermost woodland
zone was also recognized where the dominant plants form a
loose scrub of birch [Betula pubescens], mountain ash [Pyrus
Aucuparia], holly [Ilex Aquifolium], hawthorn [Grataegus Oxy-
acantha], blackthorn [Prunus spinosa], and willows [S. cinerea,
8. caprea, and 8. aurita] (Smith and Kankin, 1903 : 159).

Birch woods (see figure 8) are only feebly developed in
the Peak District : none is of great extent ; and none shows
a sharp line of demarcation from the upper oak woods. As
one ascends a wooded hill-slope composed of non-calcareous
rocks, the oak (Quercus sessiliflora) becomes rare at altitudes
above 1000 feet (305 m.), and usually ceases at 1100 feet
(335 m.) or 1200 feet (366 m.). The diminution in number
of the oaks is attended by an increase in number of the birches ;
so that there is a gradual transition from oak woods to oak-
birch woods and to pure birch woods. Woods of the intermediate
oak-birch type are of frequent occurrence in Longdendale and
upper Derwentdale. Pure birch woods, however, are rare in
the Peak District, though two or three rather small examples
occur at altitudes above 1000 feet in the two valleys just
mentioned. Along with the oak, most of the other trees, such,
for example, as the alder (Alnus glutinosa), the wych elm
( Ulmus glabra = U. montana), and the ash (Fraxinus excelsior),
are left behind when the higher altitudes are reached. The
mountain ash (Pyrus Aucuparia), on the other hand, becomes
more abundant. Similarly, most of the shrubs of the oak
woods become rare at the higher altitudes, the hawthorn
(Crataegus Oxyacantha) and Salix cinerea perhaps ascending
higher than most of the others. The number of shade-loving
ground species also becomes greatly reduced ; and such species
(see page 55) are either totally absent or present in greatly

Cojii/riyht

Figure 8.

W. B. Crump

Birch Wood of Betula pubescens.

The ground is marshy, and there is a great deal of the common

Hugh (Juncus effusiiis) and of the tufted Hair-grass (Deschampsia

caespitosa).

II] WOODLAND ASSOCIATIONS 61

reduced numbers. Since no Alpine and very few sub-Alpine
species take the place of the absent lowland species, the floristic
features separating the birch woods from the oak woods are, in
this district, largely of a negative character. From the stand-
point of vegetation, however, there are positive differences, as
there is a rearrangement of the common members of the two
associations.

There is little doubt that the birch woods of Betula pube-
scens must be placed in the same plant formation as the oak
woods of Quercus sessiliftora, not merely because the two
associations are connected by all possible gradations and
because one may easily replace the other, but because the
general habitats have so much in common and the floristic
elements are so very much alike. A birch wood, in this district,
is simply a wood in which the oaks, on account of the increased
exposure consequent on the increased altitude, have largely or
entirely disappeared, and in which the birches have profited
by the absence of the competition of the oaks. However, the
difference in altitude and the consequent differences of the
flora and of the vegetation are sufficient to justify the placing
of the two communities in separate associations, in spite of
the existence of numerous connecting links.

Following a system of universal nomenclature (see Moss,
1910 6 : 41, et seq.), the two most important woodland associa-
tions of the non-calcareous soils may be designated as follows : —

(i) Quercetum sessiliflorae or association of Quercus sessiliflora.
(ii) Betuletum pubescentis or association of Betula pubescens.

Regarding these as belonging to the formation Silicion, the
above names may be combined as follows (Moss, loc. cit.} : —

(i) Silicion Querceti- sessiliflorae.
(ii) Silicion Betuleti-pubescentis.

Not only do the meagre birch woods of the Pennines
closely resemble the oak woods, but the more typical birch
woods of Perthshire would appear to be very closely allied to
the Scottish oak woods. R. Smith (1900 b: 45) in describing
the birch woods of Perthshire says: — "The birch woods in
the shelter of the river valleys may, however, have as rich a
vegetation as the oak coppice. Thus, for example, a list taken
in the birch wood between Loch Tummel and the Falls of

VEGETATION OF THE PEAK DISTRICT

[CH.

Tummel shows a flora almost identical with that already given
as characteristic of the oak coppice."

R. Smith (loc. cit.) also stated that the ground vegetation
of other examples of the Perthshire birch woods scarcely differs
from the vegetation of the adjoining grassland or moorland.
This, too, is the case with regard to some of the birch woods of
the southern Pennines. Birches, when growing spontaneously,
allow a great deal of light to pass through the canopy; and
this fact, especially when coupled with the greater altitude of
the birch woods, is sufficient to account for the smaller number
of sciophytes or shade-loving plants and the greater number of
photophytes or light-loving plants. The following lists, taken
from two oak-birch woods of the Peak District, show the nature
of the ground flora and vegetation : —

Birch woods with moor-
land vegetation (Long-
dendale).
Soil peaty and locally
wet.

Birch woods with sili-
ceous grassland vegetation
(upper Derwentdale).
Soil shaly and drier.

Sphagnum spp., and

Abundant in the cre-

Local

other mosses and

vices between the

liverworts

boulders among which

numerous fallen and

rotting birch trunks

litter the ground

Blechnum Spicant

Occasional

Rare

Pteris aquilina

Rare to locally abun-

Rare to occasional

dant

Salix caprea

Rare

S. cinerea

Rare to occasional

Betula pubescens

Very abundant

Quercus sessiliflora

Rare to locally abun-

Rare to occasional

dant

Pyrus Aucuparia

Occasional

Rare

Crataegus Oxyacantha

Rare to abundant

Occasional

Galium saxatile

Occasional

Calluna vulgaris \

Completely covering

Rare

Vaccinium Myrtillus I

many of the numerous

V. Vitis-idaea )

rocks which strew the

ground

Agrostis tenuis

Occasional

Occasional to abundant

Deschampsia flexuosa

Abundant

Rare to abundant

Molinia caerulea

Locally abundant

—

Festuca ovina

Occasional

Nardus stricta

Occasional to abundant

Abundant

Carex pilulifera

Rare

II] WOODLAND ASSOCIATIONS 63

Very few of the rare and characteristic herbaceous species
of the Scottish birch woods occur in Great Britain so far south
as Derbyshire. For example, the following species, which
occur in the Scottish birch woods (R. Smith, 1900 6) are
absent from Derbyshire : —

Pyrola secunda Linnaea borealis

P. rotundifolia Corallorrhiza trifida
Moneses uniflora ( = C. innata)

( = M. grandiflora) Goodyera repens

Of the above, the coral-root stops at the Border : Goodyera
almost stops at Cumberland, but has outlying stations in
Yorkshire and Norfolk : Moneses (Pyrola) uniflora is unknown
in England : P. secunda and Linnaea are rare in northern
England ; and P. rotundifolia is a very local plant throughout
southern Britain. Listera cordata and Trientalis europaea,
which are found in birch woods in Scotland, exist on the
Pennines only as moorland plants1 ; and, even on the moors,
they are rare and local. Pyrola media and P. minor appear,
in fact, to be the only species of this class which are typical of
both the Scottish birch woods and the upper woodland zone of
northern England ; and even these species are rare and local
throughout the whole of England.

The Primitive Birch-Forest

Judging from the timber which is not infrequently found
buried under the peat of the Pennines, it is certain that in former
times a very extensive upland zone of birch woods existed on
the Pennines; and the meagre birch woods which now occur
on the Pennines are to be regarded as the vestiges of a former
widespread plant association (cf. Smith arid Rankin, 1903 : 160).
Although birches are quite commonly met with under the
peat on certain of the moors of the district, one hesitates to
refer to such a layer as a continuous forest bed. The layer is

1 It has recently been stated (Williams, 1910 : 127) that Trientalis europaea
grows "in woods" at Halifax, which is the southern British limit for this plant.
As a matter of fact, the plant in that locality is confined to a small space where
it grows among bilberry and mat-grass on a treeless hill side. Wheldon and
Wilson (1907: 239) state that on the Pennines farther north the plant grows
on "moorlands amongst bilberry, bracken, and heather."

64 VEGETATION OF THE PEAK DISTRICT [CH.

not continuous under the peat of the southern Pennines, at all
events : the birch remains do not exist, for example, on the ex-
posed ridges, and they are absent from certain exposed hill sides :
they frequently follow the hollows worn out by the streams;
and, at their highest limit, they are practically limited to the
stream banks. It seems to me unreasonable to elevate these
discontinuous birch remains almost to the rank of a geological
formation, as is done by some writers on peat ; and it seems best
to speak of them simply as the remains of a former birch forest,
since their occurrence is exactly what one would expect them to
be assuming they are the remains of a thin and open forest
which once occurred at the upper local limit of woodland.

This ancient birch forest is wholly a post-glacial affair ; and
the reduction in altitude of the forest limit illustrates what
is perhaps a general law that in any district where a forest
exists at its extreme limits, climatic or otherwise, the forest
will as time goes on exhibit retrogressive tendencies. The
latter are usually intensified by human interferences, such as
by felling and by the grazing of domestic animals, and, on the
other hand, they may be retarded by human interference, as
by the careful replanting of the indigenous trees ; but, left to
itself, any forest which exists at its climatic or edaphic limits
will, in all probability, become degenerate in time. The causes
of this degeneration are discussed rather more fully in the next
chapter (see page 91).

It seems to be the case that, in this primitive Pennine
birch forest, the Scots pine (Pinus sylvestris) occurred. How-
ever, as pine timber is only rarely met with under the peat
of the Pennine moors, and as birch timber is abundant, it is
impossible to postulate a general zone of pine forest at a
different altitude from the birch forest. Probably the pine
occurred much more rarely than the birch, either as an
occasional associate in the birch association, or it formed smaller
associations or societies here and there. On these assumptions,
the ancient forest on the upper slopes of the Pennines would
be regarded as part of the forest region of north-western
Europe, but not, as is the case of the woodlands with birch
and pine in southern England, as part of the forest region
including the north German plain. The pine probably became
extinct here at an early date ; and the existing trees have, in

II] WOODLAND ASSOCIATIONS 65

all probability, either been planted, or they are the descendants
of planted trees. The latter is much the more rare occurrence,
as few pine seedlings are met with in this district.

ASH WOODS OF FRAXINUS EXCELSIOR

Ash woods are characteristic of the slopes of the limestone
hills of the west and north of England. In previous British
vegetation memoirs, woods of this type have been described on
the limestone of the mid-Pennines (Smith and Rankin, 1903),
in Westmorland (Lewis, 1904 a), and in Somerset (Moss, 1907 a).
They do not appear to have been described by continental plant
geographers. Smith and Rankin (1903 : 168 et seq.) mentioned
three sub-types. The first of these, which they termed " scar
woods," occurs on the slopes of hills of the Carboniferous Lime-
stone : such " scar woods " are more of the nature of scrub than
of woodland. "The hazel [Corylus Avellana] is the dominant
element most commonly found ; but the ash [Fraxinus excelsior]
occurs frequently, and sometimes close enough to reduce the
hazel to a subdominant form.... As a rule, the ash occurs but
sparingly, because, being almost the only timber tree in the
limestone dales, it is generally removed. In this district, few
of the woods receive any attention ; and little is done to check
disforesting. Almost all the scar woods are therefore to be
regarded as shrubby thickets " [i.e., as scrub]. These ash and
hazel scrubs are interesting in that they still furnish the habitat
of that rare British orchid, the lady's slipper (Cypripedium
Calceolus). The second sub- type mentioned by Smith and
Rankin occurs at lower levels on the Permian or Magnesian
Limestone and in the bottoms of the dales of the Carboniferous
Limestone, and consists of ash woods which have been much
altered by planting beech, oak, sycamore, pine, and larch.
The third sub-type is termed a " hazel copse of the Permian,"
and is made up of scrub occurring on the Permian limestone.
Lewis gives only a brief account of the woods of the district
which he investigated; and it is not easy to relate them to
general woodland types. However, the "birch woods" men-
tioned by him (1904 a: 319), judging from their occurrence at
comparatively high altitudes on limestone and from the list of
associated species, would appear to belong to the general ash

66 VEGETATION OF THE PEAK DISTRICT [CH.

type, and to the association of ash-birch woods (cf. p. 40). In
Somerset (Moss, 1907 : 41), ash woods are well developed on
the slopes of hills of Carboniferous Limestone, of the Dolomitic
Conglomerate, and of the Jurassic limestones. The "oak-hazel
woods" of Somerset (Moss, 1907 : 51) also are to be regarded as
conforming to the general ash wood type (see Watson, 1909 ;
and Moss, Rankin, and Tansley, 1910: 138). "Oak-hazel
woods," i.e., woods with oak standards and much hazel coppice,
are of very general occurrence throughout southern England.
Some of them have been derived from oak (Quercus Robur)
woods, and others from ash-oak woods. The "oak-hazel woods"
of Somerset must be referred to the latter class, because they
contain among the coppiced layer a great deal of ash, which
would spring up as standard trees if not coppiced, and because
their "ground flora resembles the more shady portions of the
ash wood" (Moss 1907: 52).

In the Peak District, typical ash woods occur on the slopes
of the hills of the Carboniferous or Mountain Limestone (see
figures 9, 10 and 17). None is represented in the northern
area, as there no limestone rocks occur. In the southern
area, they are well represented, especially in Wye dale and
Lathkill dale.

The Carboniferous Limestone rocks of north Derbyshire form
a plateau which attains a height of about 1550 feet (472 m.),
and whose average height is perhaps 1200 feet (366 m.). The
plateau is dissected by numerous valleys or "dales," most of
which are streamless. The limestone dales of the Pennines are
comparable with the gorges and coombes of the Mendip Hills
of Somerset, both from the standpoint of the geology and that
of the vegetation. The dales of Derbyshire descend from the
plateau, and the ash woods begin to appear on the slopes at an
altitude of about 1000 feet (305 m.), above which altitude scrub
occurs, but no genuine woods. The woods continue to the
bottoms of the dales, which here descend to about 250 feet
(76 m.). This is much lower than any of the ash woods
or scrub on the Carboniferous Limestones of the mid-Pennines ;
and, as in Somerset, the lower altitude permits of a better
development of the dominant tree and the more characteristic
shrubs and ground species of the ash woods.

It is probable that at some past time, the whole of the

Figure 9.
Ash Wood of Fraxinus excelsior.

W. B. Cr umi>

General view. The wood clothes steep, rocky slopes of Car-
boniferous Limestone. In the foreground is a pool with Water-
crowfoot and with marginal marsh plants.

II] WOODLAND ASSOCIATIONS 67

limestone slopes and the more sheltered portions of the
limestone plateau were covered by a primaeval ash forest, just
as similar places on the sandstones and shales were once
covered by forests of oak (Quercus sessiliftora) and birch (Betula
pubescens). The numerous place-names including the word
"ash" indicate that the dominance of the ash in the Peak
District is of long standing. Of such names, one may mention
Ashwood dale, Ashford dale, Money Ash ( = many ash), and, on
the edge of the plateau at the woodland limit, One Ash.

On the Chalk rocks of the south and east of England, the
ash is a very abundant and characteristic plant, though its
dominance in woods is apparently confined to their south-
western margin, where ash woods occasionally occur (cf. Moss,
Rankin, and Tansley, 1910: 137).

The recognition of the ash woods in England may fairly
be claimed as a result of the method of vegetation survey, as
their occurrence had apparently been quite overlooked both by
foresters and botanists; and, as already stated, ash woods are
undescribed for the continent of Europe. As Elwes (1908, iv :
870) has stated that the ash is probably the only hardwood
which, at the present time, it pays to cultivate, it is obviously
a matter of economic importance to note the distribution of
spontaneous ash woods.

Although many of the ash woods have been interfered with,
there can be no doubt that they represent the typical and
natural vegetation of the calcareous hill slopes of northern and
western England. Some of the ash woods show no signs of
planting, and possess, in fact, all the attributes of a primitive
plant association. The ash produces ripe seeds ; and seedlings
in all stages occur in abundance. The land agents and keepers
of the ash woods assert that the ash is not planted, but that it
springs up everywhere " like a weed." Many of the slopes on
which the ash woods occur are too rocky and precipitous to have
ever been enclosed as farmland (figure 9) ; and even on the less
rocky slopes where the woods have degenerated into scrub and
grassland, the land is not always reclaimed, but often remains
uncultivated. Further, the associated trees, shrubs, and ground
species are such as botanists agree in regarding as members of
the primitive flora of the country. It is legitimate and reason-
able, therefore, to regard the ash woods as primitive.

5—2

68 VEGETATION OF THE PEAK DISTRICT [CH.

The ash woods on the limestone slopes have the same
altitudinal range as the oak (Quercus sessiliflora) woods on the
slopes of the sandstones and shales ; that is, they range from
the valley bottoms up to about 1000 feet (305 m.).

Semi-natural Woods and Plantations
on the Limestone Slopes

Some of the slopes of the limestone hills with a deeper and
a damper soil are utilized by the foresters for the growth of
marketable timber; and the beech (*Fagus sylvatica), the
sycamore (*Acer Pseudoplatanus), the larch (*Larix detidua),
and other trees are planted. Owing to the dip of the rock-strata,
one side of narrow valleys is usually damper than the other;
and hence it is unusual to find that the opposite sides of the
dales have quite similar vegetation. One may find, for example,
that the damper slope is planted up with beeches, sycamores,
larches, and other introduced trees, and that the opposite side
is characterized by a perfectly spontaneous ash wood ; and thus
it is in parts of Lathkilldale. In some cases, where alien trees
have been planted on the site of a previous ash wood, the
primitive flora lingers on for some time. For example, the
lily-of- the- valley (Convallaria majalis) and the broad-leaved
helleborine (Helleborine latifolia) still linger on, but do not
flower freely, under introduced beeches in Lathkilldale. In
other cases, the alien trees have been planted on calcareous
grassland. In such plantations, one does not find the rarer
and more characteristic plants of the ash woods; but some
of the more general and ubiquitous woodland species, such
as Geuni, urbanum and Lychnis dioica, sooner or later invade
them. On the accompanying vegetation maps, the great
abundance of introduced trees is, where possible, indicated by
the initial letter of the alien tree being planted over the wood-
land colour; and thus it is often possible to infer from the maps
whether alien trees have been planted in a wood or not. The
maps, therefore, have a far greater value to foresters than any
previously constructed maps, such as the Ordnance maps or
the small scale maps issued by various publishers, as even the
best of these maps do not attempt to distinguish more than
deciduous woods and coniferous woods ; and even this simple

II] WOODLAND ASSOCIATIONS 69

distinction is sometimes made inaccurately. Further, none of
these maps attempts to distinguish between natural and semi-
natural woods on the one hand and obviously artificial planta-
tions on the other.

Trees and Shrubs

The ash (Fraxinus excelsior) is dominant throughout the
length and breadth of the ash woods (see figure 9); and in
them it is not confined, as it is in the oak woods, to the damper
situations. It seems -clear that, in any given natural station,
the abundance of the ash is due to one of two causes, either to
a high water-content or to a high lime-content. Some of the
local foresters are of opinion that the timber of the ash grown
on the limestone soils is harder and more durable than that
grown on the wet, non-calcareous soils.

The two most frequent arboreal associates of the ash are the
wych elm (Ulmus glabra-= U. montana) and the hawthorn
(Crataegus Oxyacantha), both of which are here more generally
distributed than in the oak or birch woods. The elm is more
abundant at the lower altitudes and in the damper situations
(see figure 10), the hawthorn in the drier situations and at
the higher altitudes. When the ash, the most valuable timber
tree of the dales, is removed or dies out in a degenerating
wood, the elm or the hawthorn, as the case may be, becomes
locally subdominant ; and societies of elm and hawthorn are as
characteristic of the ash woods as birch and alder societies are
of oak woods. On the vegetation maps, these societies are in-
dicated by the same colour as the ash association of which they
form a part ; but, where practicable, the initial letter or letters
of the genus of the locally subdominant tree is printed on
the general woodland colour. An example of a society of wych
elms occurs in upper Middleton Dale; and hawthorn societies
are typical of most of the upper parts of drier dales.

Two conifers are native in the ash woods. One of these,
the juniper ("Juniperus communis") is very rare, and ap-
parently confined to one place: the other, the yew (Taxus
baccata) is not common ; but small specimens occur here and
there on the ledges of limestone cliffs in the ash woods. It is
rather curious that these plants should be so uncommon here,

68 VEGETATION OF THE PEAK DISTRICT [CH.

The ash woods on the limestone slopes have the same
altitudinal range as the oak (Quercus sessiliflora) woods on the
slopes of the sandstones and shales; that is, they range from
the valley bottoms up to about 1000 feet (305 m.).

Semi-natural Woods and Plantations
on the Limestone Slopes

Some of the slopes of the limestone hills with a deeper and
a damper soil are utilized by the foresters for the growth of
marketable timber; and the beech (*Fagus sylvatica), the
sycamore (*Acer Pseudoplatanus), the larch (*Larix deddua),
and other trees are planted. Owing to the dip of the rock-strata,
one side of narrow valleys is usually damper than the other;
and hence it is unusual to find that the opposite sides of the
dales have quite similar vegetation. One may find, for example,
that the damper slope is planted up with beeches, sycamores,
larches, and other introduced trees, and that the opposite side
is characterized by a perfectly spontaneous ash wood ; and thus
it is in parts of Lathkilldale. In some cases, where alien trees
have been planted on the site of a previous ash wood, the
primitive flora lingers on for some time. For example, the
lily-of-the- valley (Convallaria majalis) and the broad-leaved
helleborine (Helleborine latifolia) still linger on, but do not
flower freely, under introduced beeches in Lathkilldale. In
other cases, the alien trees have been planted on calcareous
grassland. In such plantations, one does not find the rarer
and more characteristic plants of the ash woods; but some
of the more general and ubiquitous woodland species, such
as Geunt urbanum and Lychnis dioica, sooner or later invade
them. On the accompanying vegetation maps, the great
abundance of introduced trees is, where possible, indicated by
the initial letter of the alien tree being planted over the wood-
land colour; and thus it is often possible to infer from the maps
whether alien trees have been planted in a wood or not. The
maps, therefore, have a far greater value to foresters than any
previously constructed maps, such as the Ordnance maps or
the small scale maps issued by various publishers, as even the
best of these maps do not attempt to distinguish more than
deciduous woods and coniferous woods ; and even this simple

II] WOODLAND ASSOCIATIONS 69

Trees and Shrubs

The two most frequent arboreal associates of the ash are the
wych elm (Ulmus gldbra-= U. montana) and the hawthorn
(Crataegus Oxyacantha), both of which are here more generally
distributed than in the oak or birch woods. The elm is more
abundant at the lower altitudes and in the damper situations
(see figure 10), the hawthorn in the drier situations and at
the higher altitudes. When the ash, the most valuable timber
tree of the dales, is removed or dies out in a degenerating
wood, the elm or the hawthorn, as the case may be, becomes
locally subdominant ; and societies of elm and hawthorn are as
characteristic of the ash woods as birch and alder societies are
of oak woods. On the vegetation maps, these societies are in-
dicated by the same colour as the ash association of which they
form a part ; but, where practicable, the initial letter or letters
of the genus of the locally subdominant tree is printed on
the general woodland colour. An example of a society of wych
elms occurs in upper Middleton Dale; and hawthorn societies
are typical of most of the upper parts of drier dales.

Two conifers are native in the ash woods. One of these,
the juniper ("Juniperus communis") is very rare, and ap-
parently confined to one place : the other, the yew (Taxus
baccata) is not common ; but small specimens occur here and
there on the ledges of limestone cliffs in the ash woods. It is
rather curious that these plants should be so uncommon here,

70 VEGETATION OF THE PEAK DISTRICT [OH.

as they are very much more abundant further south, as on the
Chalk of south-eastern England, and on limestone further north,
as in north-west Lancashire.

Of introduced conifers, the larch (*Larix decidua) and the
Scots pine (*Pinus sylvestris) are locally very abundant; but
no evidence has been obtained that either of these trees
rejuvenates itself from self-sown seed.

The aspen (Populus tremula) is the only indigenous poplar
of the Peak District. It is decidedly uncommon on the whole;
but occasionally, as in Cressbrookdale, aspen societies occur.

Of willows which are certainly indigenous, there are the
crack willow (Salix fragilis), the osier willow (S. viminalis),
and the sallows (S. caprea and 8. cinerea); but 8. alba,
8. triandra, S. pentandra, S. purpurea, x S. Smithiana also
occur by some of the stream sides. . S. aurita and S. repens
appear to be absent from the limestones.

The hazel (Corylus Avellana) is a very abundant and
characteristic shrub, more so even than in the oak woods.
Dense thickets of hazel frequently occur, especially in the
subordinate scrub associations (see next chapter).

The alder (Alnus glutinosa) is even less abundant and less
characteristic in the ash than in the oak woods ; but locally it
forms societies at the bottom of some of the damper dales, as in
Cressbrookdale.

Birches are as rare as oaks in the ash woods of the Peak
District, and are perhaps not indigenous. *Betula alba and
*B. pubescens have both been planted in Haydale (Monsaldale),
along with beeches and conifers, on the site of a former ash
wood. The absence of oaks and birches from the ash woods
of this district is interesting; as, in other parts of England,
both trees occur more or less abundantly in ash woods.

Oaks are very rare and perhaps not indigenous on the
Carboniferous Limestone of the Peak District. In the Wye
valley, which is locally well wooded, only about half a dozen
oaks were noted ; and these did not occur in the more primitive
of the ash woods, but only among trees which were obviously
introduced, as in parklands and plantations.

The beech (*Fagus sylvatica) is planted abundantly, but
does not appear to be indigenous on the Pennines.

Several species of Ribes (R. Orossularia, R. alpinum,

C<n>yri<jld

Figure 10.

Ash Wood of Fraxi nits excelsior.

A society of Wych Elms (Ulinun glabrn-V. montaiia). The

ground vegetation to the left of the footpath consists very largely

of Dog's Mercury (Mercurialis perennis).

II] WOODLAND ASSOCIATIONS 71

R. nigrum, R. rubrum) also occur ; but these, with the possible
exception of R. alpinum, are perhaps not indigenous.

Ericaceous undershrubs are totally absent from the ash
woods ; and this appears to apply to all the woods of the ash
and beech associations (see page 40) throughout the country.

One of the most noticeable features of ash woods, both here
and elsewhere, is the large number of arboreal and shrubby
species which occur in the association. The shrubs are some-
times very dense, and almost impenetrable. The following
species, which are absent or nearly absent from the oak and
birch woods, are characteristic of the ash woods of the Peak
District : —

"Juniperus communis" (rare) Euonymus europaeus

Taxus baccata (local) Rhamnus catharticus

Populus tremula (local) Tilia cordata (rare)

Ribes alpinum (local) Daphne Mezereum (rare)

Pyrus Aria (rare) D. Laureola (local)

Rosa spinosissima (local) Cornus sanguinea

R. micrantha (rare) Ligustrum vulgare

Herbaceous Vegetation

The two most characteristic ground societies of the oak
woods, namely the hair-grass society and the soft-grass society
(see pages 55 and 56), do not occur at all in the ash woods. The
hair-grass society is, it will be remembered, characteristic of
those portions of the oak and birch woods whose soils have
a high content of acidic humus; and the soft-grass society
occurs in the drier parts of the oak woods whose soils have
a lower, but still a decidedly appreciable proportion of acidic
humus. Such humus does not accumulate in the ash woods.

The ash woods cannot be separated from the oak woods on
the basis of differences in the water-content of the soil of the
two plant communities ; for in each case there is a range from
very wet to very dry soils. The lime-content in the two cases,
however, is always strikingly different; and there are no soils
in the ash woods with a high content of acidic humus such as
very frequently characterise the soils of the oak and birch
woods. The following divisions of the ground vegetation will
illustrate the range in habitat within the ash woods of the
district.

72 VEGETATION OF THE PEAK DISTRICT [CH.

1. Marshy places. In marshy places, which occur in
the ash woods by stream sides, at the bottoms of some of
the streamless dales, and in places where springs arise, such
moisture-loving plants as the following occur, in addition to
such indigenous trees as the ash, the alder, and the crack
willow : —

Trollius europaeus (local) Valeriana officinalis

Caltha palustris Petasites ovatus

Spiraea Ulmaria Cnicus heterophyllus

Geum rivale Phragmites communis

G. rivale x urbanum Phalaris arundinacea

Epilobium hirsutum Scirpus compressus (rare)

Myosotis palustris Sparganium ramosum

Mentha aquatica Orchis maculata

2. Damp places. Other parts of the ash woods although
not really marshy, are nearly always, very moist; and such
places, like similar ones in the oak woods, have a rich and
varied ground flora. The trees are here usually well grown;
and the wych elm is frequently abundant (see figure 10).
Sheets of wood-garlic (Allium ursinum) and of the lesser celan-
dine (Ranunculus Ficaria) are characteristic. The following is
a selected list of the ground species of such parts of the ash
woods : —

Nephrodium Filix-mas V. dioica (local)

Lychnis dioica Campanula latifolia (local)

Anemone nemorosa Cnicus palustris

Ranunculus Ficaria C. heterophyllus (local)

Trollius europaeus (local) Deschampsia caespitosa

Aquilegia vulgaris (local) Bromus ramosus

Fragaria vesca Triticum caninum (local)

Geum rivale Hordeum europaeum
G. rivale x urbanum ( = H. sylvaticum) (local)

Oxalis Acetosella Carex sylvatica

Polemonium coeruleum (local) Arum maculatum

Myosotis sylvatica Allium ursinum

Lamium Galeobdolon Orchis maculata

Asperula odorata Habenaria virescens
Valeriana officinalis ( = H. chloroleuca) (local)

3. Dry places. On soils which are drier than the pre-
ceding, and which, during the summer months, may in fact
become temporarily very dry, expanses of dog's mercury (Mer-
curialis perennis) often occur ; and this plant is here frequently
associated with the tiny moschatel (Adoxa Moschatellina). At

II] WOODLAND ASSOCIATIONS 73

the beginning of April, in the Derbyshire dales, the dog's
mercury is about three inches high : its leaves are beginning to
unfold ; and a few stamens are ripe. At this time of the year,
the moschatel is here flowering abundantly, and is almost
hidden by the young shoots of the dog's mercury. In the
fairly dry portions of the ash woods of the Peak District, this
ground society of dog's mercury and moschatel is a character-
istic feature. The society is an excellent example of what
Woodhead(1906: 345) would term a "complementary" society,
as the roots of the dog's mercury reach down to lower layers of
soil than the roots of the moschatel, whilst the small and delicate
shoots of the Adoxa receive their necessary shade from the larger
and more vigorous shoots of Mercurialis. Before the end of
June, Adoxa has entered on its long period of dormancy ; and
the dull green leaves of the dog's mercury, hiding its ripening
berries, occur in extensive and monotonous stretches. It may,
therefore, be said that the roots of the two species are edaphi-
cally complementary and the shoots seasonably complementary.
In the oak and birch woods, the dog's mercury occurs in more
or less local patches, and Adoxa is extremely rare ; whilst the
Mercurialis-Adoxa society does not occur.

The dog's mercury is much more abundant, especially as a
social species, in English woods on calcareous soils than in those
on non-calcareous soils ; and this is a partial confirmation of an
observation made by Thurmann (1849) who mentions the plant
as one of fifty " xerophilous " plants typical of " dysgeogenous "
or calcareous soils.

Still drier parts of the ash woods are characterized by
stretches of ground ivy (Nepeta hederacea) which remains green
throughout the whole year and which flowers from early spring
to late summer. If the ground is stony and composed of old
screes, taller herbs occur, such as the hairy St John's wort
(Hypericum hirsutum), the nettle ( Urtica dioica), and the wood
sage (Teucrium Scorodonia). These plants form close herbaceous
thickets in summer ; and their dead stalks remain upright and
rigid throughout the succeeding winter and spring. Locally,
the lily-of-the-valley (Convallaria majalis) and the stone-
bramble (Rubus saxatilis) form fairly extensive plant societies ;
and in these, the nodding melic-grass (Melica nutans) and Helle-
borine atro-rubens sometimes occur.

74 VEGETATION OF THE PEAK DISTRICT [CH.

4. Rocky knolls. The very driest parts of the ash woods
occur on the rocky knolls. Here the soil is extremely shallow;
and in places the bare rock protrudes. Trees and shrubs are
absent; and the absence of shade allows of the growth of
saxicolous lichens and bryophytes, of such ephemeral species as
Arenaria serpyllifolia, Erophila verna, and Saxifraga tridac-
tylites, and of such dwarf perennials as Sedum acre and Thymus
Serpyllum. Such a community does not, except in a topo-
graphical sense, belong to a woodland association at all, and
is to be regarded as an outlier of another association.

Limestone screes and cliffs also occur in the midst of the
ash woods. These, if damp, become in time clothed with the
vegetation of the ash woods ; and, by comparing several such
localities, it is possible to gain some idea of a progressive
succession from bare screes and cliffs to a closed ash association.
Such a succession supplies the reason, a historical one, why
such plants as the mossy saxifrage {Saxifraga hypnoides} and
the limestone polypody (Phegopteris Robertiana) are sometimes
found on old screes in the midst of existing ash woods.

COMPARISON OF THE WOODLAND PLANTS
OF THE SOUTHERN PENNINES

The numerous trees and shrubs which occur in the ash
woods and which are absent from the oak and birch woods have
already been mentioned (see page 71). To the species of this
class there mentioned, the following herbaceous plants may be
added : —

Polypodium vulgare Poterium Sanguisorba

Phegopteris Robertiana Geranium lucidum

Phyllitis Scolopendrium G. sanguineum

( = S. vulgare) Hypericum montanum

Asplenium Trichomones H. hirsutum

A. Adiantum nigrum Helianthemum Chamaecistus

A. Ruta-muraria Viola hirta

Cystopteris fragilis V. sylvestris

Helleborus viridis Pimpinella major

" H. foetidus " Polemonium coeruleum

Cardamine impatiens " Lithospermum oflficinale"

Draba muralis Satureia Acinos

Sedum Telephium S. vulgaris

Saxifraga hypnoides (=Calamintha Clinopodium)

S. Tridactylites Origanum vulgare

Figure 11.
Maps of Cressbrook Dale.

Left-hand map. The unshaded parts (| |) consist of permanent

pasture : — (1) of valley bottom alluvium, (2) of intakes from the hill-
slopes, (3) of the plateau. The cross-hatched parts (BH1 ) consist
of calcareous grassland. The hatched parts (|||||||) consist of cal-
careous scrub. The stippled parts (^ S|) consist of ash woods.
Right-hand map. The same area with contour-lines in feet (1000 feet =
302 m.). The rocks consist entirely of Carboniferous Limestone.

II] WOODLAND ASSOCIATIONS 75

"Atropa Belladonna" Centaurea Scabiosa

Galium verum Picris hieracioides

G. sylvestre Hieracium spp.

"Rubia peregrina" H. sciaphilum

Dipsacus pilosus H. britannicum

Scabiosa Columbaria Carex ornithopoda

Campanula Trachelium Scirpus compressus

Eupatorium cannabinum " Polygonatum multiflorum "

Inula squarrosa "P. officinale"

( = 1. Conyza) Helleborine atro-rubens
Arctium nemorosum ( = Epipactis atro-rubens)

Serratula tinctoria "Orchis pyramidalis"

On the other hand, the following species are found in the
oak and birch woods, and are absent from the ash woods of the
Peak District: —

Trees and shrubs

Salix aurita Quercus sessiliflora

Betula pubescens Rhamnus Frangula

Undershrubs

Salix repens Erica cinerea

Ulex Gallii Calluna vulgaris

U. europaeus Vaccinium Myrtillus

Cytisus scoparius V. Vitis-idaea

Herbaceous species

Equisetum sylvaticum Jasione montana

Cryptogamma crispa Wahlenbergia hederacea

Blechnum spicant Gnaphalium sylvaticum

Nephrodium montanum Senecio sylvatica

N. spinulosum Holcus mollis

Corydalis claviculata Deschampsia flexuosa

Pyrola minor Molinia caerulea

P. media Carex binervis

Scutellaria minor C. helodes
Digitalis purpurea ( = C. laevigata) ,

Melampyrum pratense (agg.) Luzula sylvatica

Galium saxatile Orchis ericetorum

Several species, whilst occurring both in the ash and in
the oak and birch woods, ascend to higher altitudes in the
former than in the latter; and the following are examples of
such species : —

76 VEGETATION OF THE PEAK DISTRICT [OH.

Ulmus glabra Chaerophyllum temulum

( = U. montana) Cnicus heterophyllus

Sisymbrium officinalis Phragmites communis

Geum urbanum Arrhenatherum elatius
Rubus caesius ( = A. avenaceum)

Rosa arvensis Bracbypodium gracile

Vicia sepium Arum maculatum

Acer campestre Allium ursinum

Sanicula europaea Tamus communis

Caucalis Anthriscus Orcbis mascula

The ash woods are much richer in species than the oak
and birch woods, in spite of the fact that the species character-
istic of soils containing acidic humus are abundant in the
latter woods and absent from the former woods. Indeed, the
floristic wealth of the ash woods is even greater than mere
lists indicate, for several of the species which are rare and
local in the oak and birch woods are more abundant and
general in the ash woods. The following species belong to the
latter class : —

Populus tremula Valeriana officinalis

Mercurialis perennis Campanula latifolia1

Trollius europaeus Cnicus heterophyllus1

Aquilegia vulgaris1 Poa nemoralis

Sisymbrium officinalis Melica nutans1

Rubus saxatilis1 Agropyrum caninum

Rosa tomentosa Festuca sylvatica

R. glauca Hordeum europaeum1

R. arvensis Carex sylvatica1

Pyrus Aria1 Paris quadrifolia1

Geranium sylvaticum1 Convallaria majalis1

Polygala vulgaris Helleborine latifolia
Tilia cordata1 ( = Epipactis latifolia)

Acer campestre Listera ovata

Primula vulgaris Orchis mascula

Myosotis sylvatica1 Habenaria virescens
Adoxa Moschatellina ( = H. chlorantha)

Some species which are characteristic of the ash woods of
Yorkshire (cf. Smith and Rankin, 1903) do not occur so far
south as Derbyshire, and apparently find the intervening
non-calcareous soils an effectual barrier. Actaea spicata,

1 These species are not recorded by Linton (1903) for any of the oak woods
of Derbyshire ; but they occur in such woods on the eastern slopes of the Pennines
a little to the north of the Peak District.

II] WOODLAND ASSOCIATIONS 77

Melampyrum sylvaticum, and Cypripedium Calceolus are
examples, though, judging from an old record, cited in Linton's
flora (1903 : 274), the last-named species seems to have occurred
formerly in Derbyshire.

The following plants are found in ash woods of Derbyshire,
but do not occur so far south as Somerset, and are hence absent
from woods of the ash type in the latter locality : —

Stellaria nemorum Campanula latifolia

Cardamine amara Cnicus heterophyllus

Trollius europaeus Melica nutans

Geranium sylvaticum Festuca sylvatica

Polemonium coeruleum Hordeum sylvaticum

Myosotis sylvatica Carex ornithopoda

On the other hand, the following plants occur in woods of
the ash type in Somerset, but have not been noticed during the
present survey in those of the hills of the Peak District : —

Clematis Vitalba Viburnum Lantana

Aconitum Napellus Calamagrostis Epigejos

Euphorbia pilosa Colchicum autumnale

E. amygdaloides Cephalanthera grandiflora

Lithospermum purpureo-coeruleum Ornithogalum pyrenaicum

The autumn saffron (Colchicum autumnale) is indigenous in
pastures on the Permian limestone; but it is not a woodland
plant in the north of England, as it is in Somerset and
Cambridgeshire.

The following lime-loving and shade-loving species occur on
the lowland Permian limestone tract to the east of the Pennines,
but are absent from the woods of the Carboniferous Limestone
of the Peak District : —

Astragalus glycyphyllos Viburnum Lantana

Galium MoUugo Calamagrostis Epigejos

Generally, it is clear that the ash woods occurring on the
calcareous soils of England are richer in species than the oak
and birch woods occurring on the non-calcareous soils, and that
of species common to both types of wood, many are more
abundant and ascend to higher altitudes there than in the oak
and birch woods. These facts can scarcely be held to support
a statement sometimes made that calcium carbonate acts
deleteriously on plants. Woodhead (1906 : 396) states that
his study of the woods around Huddersfield " indicates that in

78 VEGETATION OF THE PEAK DISTRICT [CH.

this district, the physical properties of the soil and accompanying
conditions play a more important part in determining the
character of the plant associations and the distribution of
species than the chemical composition of the soil." It has,
however, to be remembered that the district investigated by
Woodhead is quite destitute of calcareous soils. My own
observations lead me to believe that in western Europe the
presence or comparative absence of calcareous compounds in
the soil is, directly or indirectly, a factor of prime importance
in the distribution both of plant communities and of species,
that within the limits of any particular district possessing only
calcareous soils the water-content of the soil is a factor of great
importance, and that within the limits of any particular non-
calcareous area two soil factors have to be considered, namely,
the amount of water and the amount of acidic humus. This
view is essentially in harmony with that taken up by Graebner
(1895, 1901, 1909, 1910), and by Nilsson (1902). Graebner
has maintained that natural divisions of vegetation will only be
reached by basing the classification on the richness or poverty
of the soil, whilst the water-content of the soil furnishes a
useful factor for the subdivision of the vegetation-divisions
thus obtained. It is probable, however, in districts such as the
higher Alps and in tropical countries, that other master-factors
come into play having a more important effect on vegetation
than the presence or absence of lime in the soil ; and probably
the same occurs in some aquatic habitats, such as rapidly
flowing streams.

The following is a list of the constituent plants of the ash
(Fraxinus excelsior) woods and of the oak (Quercus sessiliflora)
woods of the Peak District. The frequency of each species is
indicated by letters in the two columns: — dominant (d), sub-
dominant (s), abundant (a), occasional (o), rare (r), very rare (vr),
local (1), occasional to abundant (o to a), etc. Herbaceous
species which are confined or almost confined to the more
shady parts of the woods are printed in thick type, and those
preferring marshy places are printed in italics. Species which
are not indigenous but which have been planted either in the
woods or on the sites of former woods are preceded by an
asterisk.

WOODLAND ASSOCIATIONS

Woods of
Fraxinus
excelsior

Woods of
Querciis
sestiliflora

Trees, shrubs, and undershrubs

"Juniperus communis"

—

Taxus baccata

—

*Pinus sylvestris

*P. austriaca

—

*Larix decidna

* Abies excelsa

Populus tremula

r, la

*P. canadensis

*P. candicans

—

"Salix pentandra"

"S. triandra"

S. fragilis

x S. Smithiana

*"S. alba"

*S. purpurea

S. viminalis

S. caprea

o to a

x cinerea

S. aurita

—

x caprea

—

x cinerea

—

S. cinerea

r to o

o to a

var. aquatica

var. oleifolia

Corylus Avellana

a, Is

o, la

Betula pubescens

o, la

forma denudata

—

var. parvifolia

—

*B. alba

(«=B. verrucosa)

Alnus glutinosa

o, la

*Fagus sylvatica

*Castanea sativa

—

*Quercus Kobur

( = Q. pedunculata)

*Q. Robur x sessiliflora

—

Q. sessiliflora

—

Ulmus glabra

( = U. montana)

*Ribes Grossularia

vr /

R. alpinum

—

*R. nigrum

—

*R. rubrum

—

Pyrus Malus

r to o

P. Aucuparia

r to o

o, la

P. Aria

*vr

Crataegus Oxyacantha

o, la

Rubus Idaeus

r, la

VEGETATION OF THE PEAK DISTRICT

[CH.

Woods of
Fraxinus
excelsior

Woods of
Quercus
tessiliflora

Trees, shrubs, and undershrubs

R. fruticosus (agg.)

R. fissus

R. Rogersii

—

R. carpinifolius

R. Lindleianus

R. pulcherrimus

R. Lindebergii

R. Selmeri

—

R. rusticanus

R. Sprengelii

—

R. leucostachys

R. Radula

R. podophyllus
R. dasyphyllus

o
a

R. corylifolius

R. caesius

Rosa spinosissima

—

"R. mollis"

" R. mollis x spinosissima "

( = R. villosa)

—

R. tomentosa

R. micrantha

—

R. obtusifolia

R. canina

o to a

o, la

var. lutetiana

var. senticosa

—

var. dumalis

var. vinacea

—

var. urbica

var. dumetorum

—

var. arvatica

var. caesia

R. glauca

R arvensis

o, la

Prunus spinosa

o to a

r to o, la

P. insititia

*vr

P. Padus

o to a

r to a

*P. avium

P. Cerasus

Ulex europaeus

—

r to o

U. Gallii

—

Ilex Aquifolium

r to a

Euonymus europaeus

r to o

—

Acer campestre

o to a

*A. Pseudoplatanus

Rhamnus Frangula

—

R. catharticus

r to o

—

Tilia cordata

"Daphne Mezereum"

—

II]

WOODLAND ASSOCIATIONS

Woods of
Fraxinus
excelsior

Woods of
Quercus
sessiliflora

Trees, shrubs, and undershrubs

"D. Laureola"

—

Hedera Helix

o to a

Cornus sanguinea

r, la

—

Erica cinerea

—

Calluna vulgaris

—

Vaccinium Myrtillus

—

V. Vitis-idaea

—

r, la

Ligustrum vulgare

—

Fraxinus excelsior

r to la

Sambueus nigra

o to la

Viburnum Opulus

Lonicera Periclymenum

Herbaceous species

Equisetum sylvaticum

—

var. capillare

—

Hymenophyllum, peltatum
Cryptogamma crispa

z .

vr
vr

Polypodium vulgare
Phegopteris polypodioides

vr
vr

P. Dryopteris
P. Robertiana

r
la

Nephrodium montanum

—

N. Filix-mas

o, la

var. paleaceum

—

N. spinulosum

—

N. aristatum

( = N. dilatatum)

o, la

Aspidium angulare

A. aculeatum

Cystopteris fragilis

—

Athyrium Filix-foemina

o, la

var. convexum

Asplenium Trichomones

o, la

—

A. Ruta-muraria

—

Phyllitis Scolopendrium

( = S. vulgare)

—

Blechnum spicant

—

Pteris aquilina

r to s

Urtica dioica

la /

Rumex nemorosus

R. Acetosa

R. Acetosella

Polygouum Bistorta

*Claytonia sibirica

—

Lychnis dioica

r to a

Stellaria nemorum

S. Holostea

VEGETATION OF THE PEAK DISTRICT

[CH.

Woods of
Fraxinus
excelsior

Woods of
Qwrcus
sessiliflora

Herbaceous species

Arenaria trinervia

Caltha palustris

Trollius europaeus

Helleborus viridis

"H. foetidus"

Aquilegia vulgaris

Anemone nemorosa

Ranunculus Ficaria

0 to 8

R. auricomus

Corydalis claviculata

—

r to o

*Iberis amara

Sisymbrium Alliaria

r to o

Cardamine amara

C. iinpatiens

—

C. flexuosa

C. pratensis

Draba muralis

*Arabis albida

Sedum Telephium

* " Saxifraga umbrosa "

S. hynoides

—

S. granulata

r to o

Chrysosplenium alternifolium

C. oppositifolium
Spiraea Ulmaria

la
I

Rubus saxatilis

Fragaria vesca

r to o

Potentilla sterilis

P. erecta

Geurn urbanum

G. rivale

G. rivale x urbanum

Poterium Sanguisorba

Vicia sepium

o to a

r to o

V. sylvatica

Lathyrus pratensis

L. montanus

Geranium sylvaticum

G. lucidum

—

G. Robertianum

G. sanguineum

r, la

Oxalis Acetosella

"Euphorbia amygdaloides "

Mercurialis perennis

o to s

*Impatiens parviflora

*Hypericum calycinum

H. Androsaemum

H. perforatum

H. hirsutum

o, la

II]

WOODLAND ASSOCIATIONS

Woods of
Fraxinus
excelsior

Woods of
Quercus
sessiliflora

Herbaceous species

H. montanum

—

H. pulchrum

Helianthemum Chamaecistus

—

Viola, palmtris

V. hirta

o to a

—

V. Riviniana

var. villosa

—

var. diversa

V. sylvestris

r to o

—

Epilobium hirsutum

E. parviflorum

r to o

E. montanum

E. angustifolium

Circaea lutetiana

var. intermedia

Sanicula europaea

r to o

JSgopodium Podagraria

Pimpinella major

r, la

—

P. Saxifraga

r to o

Conopodium majus

Myrrhis Odorata

Chaerophyllum temulum

r to o

Anthriscus sylvestris

Angelica sylvestris

Heracleum Sphondylium

Caucalis Anthriscus

Pyrola media

—

P. minor

—

" Monotropa Hypopytis "

Primula veris

r to o

P. vulgaris

P. veris x vulgaris

—

Lysimachia nemorum

r to o

Calystegia sepium

Polemonium caendeum

—

" Lithospermum omcinale "

—

Myosotis palustris

M. sylvatica

Myosotis arvensis

1 ,

var. umbrosa

—

Ajuga reptans

Teucrium Scorodonia

Scutellaria minor

—

Nepeta hederacea

r to o

Prunella vulgaris

Galeopsis Tetrahit

r to o

to o

Lamium Galeobdolon

to o

*!A maculatum

—

6—2

VEGETATION OF THE PEAK DISTRICT

Woodi of

Fraximu
exceliior

Woodii of
Querciu
teniliflara

Herbaceous species

Stachyn Hylvatica

8. officinalin

f-H. Hetonica)

Calarriintha Acinow

i. —

0. vulgare

(-0. Olinopodium)

r to o

—

Origanum vulgaro

—

ThyrnuH Serpyllmn

—

Menttia wjwttica

Af. rotundifoliti
Molanurn frulcamartt

or
I

"Atropa Belladonna"

—

Hcrojtkulv/ria nodona

"8. alata"

(«=#. EMuirti)

*Mimuiun luteus

—

Veronica montana

V. (JharnaedryM

hi;'it.;.lr purpUIfVl

—

r to a

Melampyrurn prateiiHO

—

var. niariM

—

"'/•. raoritanum

—

r to o

Lathraea Squamaria

Galium Cruciata

G. Aparine

G. verum

—

G. Maxatile

o to a

G. uylvc«tro

—

Asperula odorata

Adoza MoHchatellina

o to a

Valeria/rut dioica

V. l>ll«-i.l«ll.i:

V. Homfmcifolia

DipMacuH j>iloHUH

Campanula latifolia

C. Tracheliurn

C. rotundifolia

r to o

Wa/Uenbergia hederaceu

' —

Janione ruontana

r to o

EnMoatorium ca/nnabwum

Wofidago Virgaurea

r to o

r »"

Griaphfiliurn Mylvaticm/i

—

Inutt wjuarrowt

l'i-l,ti?.il.t-:: i,r,iil.,in

In In In

Kenecio Mylvaticnifi

Arctiurn ininiw

r to o

r to "

A. nemorosum

r to o

Carduu* paltutrit

1,1

iHpUM

WOODLAND ASSOCIATIONS

Woods of
Vraximu
excelsior

Woods of
Quercus
set$il\ftora

Herbaoeoua species

C. hfiteruphyllvu

Serratula tinctoria

—

< Vntuuroa ScabioNa

—

1. i|> .if i communis

I'M ris hioracioidoH

—

Crcpin f>aliido«a
Taraxacum officinale (agg.)

r
o

lo
o

Lactuca muraliH

Hieracium »pp.

r to o

H. boroalo

H. britannicum

...

H. Hoiaphilura

Anthoxanthum odoratum

Milium effusum

Agrostis tennis

Holcuw molliM

—

//. lainttiis

Dt'schtimpsia, cattpitota

D. floxuosa

—

Arrhenatherum olatiua

r to o

Molinia caoruloa

—

Melica nutans

r to o

M. uniflora

Dactylia gloiuorata

Poa nemoralis

P. trivialis

r to o

Fontuca ovina

F. sylvatica

F. glgantea

Broxnus ramoaus

l'i. Nti'i-ili.s

r to o

Hrarhvpoditim .sylvatioum

Agropyrum caiiinum

Hordeum europaeum

(-H. Bylvatioum)

r to o

C,t r<'.i' I't-inodi

0. palleBoena

( '. tl.'UV.'l

C. ptndula

r, to

(~C. latvigata)

—

0. sylvatica

C. ornithopoda

—

C. pilulilVni

vr
vr

r to o

Anim maculatum

r to o

Jinteut «/fW*Mjr

—

VEGETATION OF THE PEAK DISTRICT

[CH.

Woods of
Fraxinus
excelsior

Woods of
Quercus
sessiliftora

Herbaceous species

L. pilosa

Gagea lutea

Allium ursinum

r to o

Scilla non-scripta

0 to S

Polygonatum multiflorum

—

P. officinale

—

Convallaria raajalis

Paris quadrifolia

*Narcissus Pseudo-narcissus

*Galanthus nivalis

Tamus communis

Iris Pseudacoris

Neottia Nidus-avis

Listera ovata

Helleborine latifolia

var. atro-viridis

—

H. atro-rubens

—

Orchis mascula

"O. pyramidalis "

—

Habenaria virescens

(=H. chloroleuca)

r to o

H. bifolia

" Cypripedium Calceolus "

extinct

—

Musci

Tetraphis pellucida

—

Catharinea undulata

Polytrichum formosum

—

Dicranella heteromalla

Dicranum scoparium

Campylopus flexuosus
Leucobryum glaucum

—

Fissidens bryoides

F. adantioides

F. taxifolius

Rhacomitrium lanuginosum

Bryum capillare

Mnium hornum

M. undulatum

M. stellare

M. punctatum

Porotrichum alopecurum

Thuidium tamariscinum

Eurynchium praelongum

—

E. striatum

E. confertum

Plagiothecium denticulatum

P. Borrerianum

Hypnum Schreberi

WOODLAND ASSOCIATIONS

Woods of
Fraxinus
excelsior

Woods of
Quercus
sesgiliftora

Hepaticae

Hylocomium splendens

H. rugosum

Fruillania Tamarisci

—

F. dilatata

—

Lejeunia serpyllifolia

—

L. calcarea

—

L. Rosettiana

—

Radula complanata

—

Porella platyphylla

—

Blepharozia ciliaris

—

Lepidozia reptans

—

L. setacea

—

Kantia arguta

—

K. Trichomonis

—

Cepbalozia bicuspidata

—

Scapania nemorosa

—

Lophocolea bidentata

L. cuspidata

—

L. heterophylla

Plagiochila asplenoides

Jungermannia sphaerocarpa

—

J. veutricosa

—

Nardia scalaris

Fossombrosia pusilla

Pellia epiphylla

—

P. calycina

Aneura pinguis

Metzgeria furcata

Fegatella conica

Lunularia vulgaris

CHAPTER III

SCRUB ASSOCIATIONS

Past and present upper altitudinal limit of trees. Buried timber in the
peat. Degeneration of woodland. Distribution and character of the
existing scrub. Scrub in other districts. Relation of the ground
vegetation of woodland to retrogressive scrub. Progressive and
retrogressive scrub. Comparison of the types of retrogressive scrub.

PAST AND PRESENT UPPER ALTITUDINAL LIMIT OF TREES

IT was pointed out in the last chapter that the upper
altitudinal limit of oak and ash woods at the present time is
in this district about 1000 feet (305 m.) and the upper limit of
birch woods is about 1250 feet (381 m.). Isolated trees and
patches of scrub, however, ascend to about 1550 feet (472 m.);
and there can be no doubt that formerly trees ascended, in the
Peak District, to about 1750 feet (533 m.) or 1800 feet (549 m.).
These figures represent the upper limits of trees and woods on
the highest hills alone : on the lower hills, the upper limits of
trees and woods are not so high. For example, in the latitude
of Halifax (a few miles to the north of the Peak District), the
Pennines only rise to about 1550 feet (472 m.) ; and the present
tree limit there occurs at about 1250 feet (381 m.) and the
woodland limit at about 1000 feet (305 m.). According to
W. G. Smith (1911 : 20), in the Highland glens of Scotland,
birch woods sometimes ascend to an altitude of 2000 feet
(610 m.), in spite of the more northern latitude ; but here moun-
tains are massed together and rise to more than 3000 feet (915 m.).
On Ben Nevis, the highest mountain (4400 feet = 1313 m.) in
the British Isles, a tree is said to occur at 2700 feet (823 m.).
Still further north, in Scandinavia, where the mountains are
still higher, the trees commonly ascend to 3000 feet (915 m.).

CH. Ill] SCRUB ASSOCIATIONS 89

It is clear, therefore, that the upper altitudinal limit of woods
or of trees in any particular district cannot be accounted for
merely by the factors connected with the altitude of that
district, This point of view, although quite an old one, is
frequently ignored.

Smith (1911: 13) says that "tree growth ceases wherever
the wind attains such a force the formation of young shoots is
prevented. The determination of this wind zone must always
be considered in forestry. It cannot be defined as so many
feet above sea-level. The action of the wind may be very
marked on the coast itself... It is also the case in a hill-mass,
that all the zonal limits of plants are lifted up." This is indeed
quite true, and helps to explain the occurrence of woodland plants
under the peat of Cross Fell (which rises to 2930 feet = 893 m.)
at an altitude of 2400 feet (731 m.), whilst under the peat of
the Peak of Derbyshire (which only rises to 2088 feet = 636 m.)
woodland plants have not, during the course of the present
investigation, been observed higher than 1800 feet (549 m.).
It is not necessary to invoke post-glacial climatic changes to
account for apparent discrepancies of distribution of this
nature, for they can easily be paralleled by similarly apparent
discrepancies in existing vegetation.

Warming (1909 : 39) has stated that trees cease on
mountains at the altitude where they break up into separate
peaks. It seems highly probable that at the conclusion of
the glacial period, this country was invaded by Arctic- Alpine
species, and afterwards by forest or woodland species. Lewis
(1905, etc.) finds two forest layers in some of the Scottish peats,
so that perhaps there were two separate invasions of foitest
plants. However, only one such layer appears to be represented
as a rule in the peat of the Peak District, though in other parts
of England two or more layers of trees are found buried by peat.
The primitive woods probably ascended the mountains up to or
nearly up to the limit indicated by Warming. Perhaps there
was above this primitive forest limit, a narrow girdle of climatic
scrub and a still higher girdle of climatic grassland ; but, as
regards the present district, this is not certain. In any case,
from that time to this, there has been a gradual lowering of the
forest limit; and the scrub and grassland, which now characterise
the higher slopes of the district (and indeed those of Europe

90 VEGETATION OF THE PEAK DISTRICT [CH.

generally) below actual Alpine limits, are largely the result of
the retrogression or decay of the original forests.

Whilst this process of the lowering of the altitudinal
forest limit in post-glacial times has, in my opinion, been
essentially a natural process, it undoubtedly has in this, as in
most localities, been greatly aided by the indiscriminate felling
of trees by man and by the browsing of quadrupeds.

BURIED TIMBER IN THE PEAT

The most direct evidence regarding the former greater
development of forest in the district is to be derived from a
study of peat deposits. The number of memoirs dealing with
this subject is legion ; and practically all the writers have
emphasized the view that the deposition of peat, in a large
number of instances, has been preceded by the occurrence of
forest. Equal emphasis, however, must be placed on two
other facts. First, forests may degenerate and still no peat
deposits may occur on the site of them; for example, the
degeneration of woods on chalk rock or on limestone or on steep
shaly slopes is not succeeded by peat deposits. Secondly, peat
deposits may be laid down without the occurrence of any pre-
existing forest ; for example, peat is now filling up some of the
Cheshire and Shropshire meres and the Norfolk broads; and
in these localities it is clear that the vegetation preceding the
deposition of the peat was a reed swamp with no arboreal plants ;
and also on the highest parts of the Pennine watersheds, peat
may occur to the depth of twelve feet (363 cm.) or more without
there being any trace of buried timber.

During the course of this vegetation survey, many instances
of buried timber have been recorded on the field maps. The
general inferences to be drawn from the facts are that tree
trunks occur at the base of the peat of several of the heather
moors and the lower cotton-grass moors, but that on the highest
moors buried timber is frequently absent. Generally, it may
be said that remains of trees are found under the peat in the
more sheltered parts of the moor and are absent from the most
exposed places. The buried trees which have been noted
consist almost wholly of birch (probably Betula pubescens} ; but
aspen (Populus tremula), oak (probably Quercus sessiliftora),

Figure 12.

A Sandstone Clough.

Siliceous grassland of Mat-grass (Nardus stricta) and silver Hair-
grass (Deschampsia fe.ruosa) on the right. Scrub of Birches
(Betula pubescens).

Ill] SCRUB ASSOCIATIONS 91

alder (Alnus glutinosa), hazel (Coryliis Avellana), mountain ash
(Pyrus Aucuparia), and willows (probably chiefly 8. dnerea)
occur more or less rarely ; and in one locality Scots pine (Pinus
sylvestris) was found.

The highest examples of buried timber consisted wholly of
birch, and were encountered on the southern extremity of the
plateau of the Peak at an altitude of nearly 1800 feet (549 m.) ;
and generally it may be concluded that the buried timber
proves that in former times trees ascended the southern
Pennines about 200 feet (61 m.) or 250 feet (76 m.) higher
than they do at the present time, that this ancient forest was
composed principally of birches, and that more or less uncommon
associates were the aspen, oak, the alder, the hazel, the mountain
ash, the willow, and the Scots pine.

DEGENERATION OF WOODLAND

There can be no doubt that a certain amount of the
degeneration of the woodland of this district has been brought
about by the indiscriminate felling of trees, the absence of
any definite system of replanting, and the grazing of quad-
rupeds. It is doubtful, however, if these causes are quite
sufficient to account for so great a lowering of the upper limit
of forest as 250 feet (76 m.), and for so general a phenomenon.
It must be remembered that the population of the remoter
valleys, many of which are now treeless or almost so, is very
small; and the district does not appear to have ever been a
great grazing district.

The inability of certain forests to rejuvenate per se has
been pointed out by many foresters and plant geographers.
In discussing the causes of the succession of forest to heath in
north Germany, Krause (1892) emphasized the view that the
narrowing of the forest area has been largely due to errors in
sylviculture, especially to the grazing of cattle in the forest.
That such a factor is a causa vera in the degeneration of forests
is indisputable. Graebner (1901), on the other hand, lays stress
on the gradual impoverishment of the soil caused by the removal
of the tree trunks, by the gradual washing out by rain of the
soluble mineral salts originally present in the soil, and the
spreading of heath vegetation on the forest floor consequent

92 VEGETATION OF THE PEAK DISTRICT [CH.

on the formation of moor-pan (Ortstein) in sour soils.
Graebner pointed out that his explanation does not invalidate
Krause's view as a partial explanation. Graebner's theory is
a very reasonable one with regard to woods which occur on com-
paratively flat plains and plateaux ; but it is scarcely satisfactory
with regard to forests on many steep hill slopes, for, in such
places, newer and richer soil from below is often exposed by
denudation and occasional land slips may bring fresh soils from
above. As the great majority of the degenerate woods of this
locality are situated on such steep slopes, some additional
explanation of forest degeneration must be sought.

Of course, it is well known that the seedlings of most trees
fail to develop under dense shade; and, for this reason, some
forests fail to rejuvenate. For example, in the High Engadine,
in Switzerland, it has been established by means of long-
continued observations that the forests of larch (Larico decidua)
which partly cover the slopes and parts of the valleys of this
part of the Alps do not everywhere regenerate themselves from
seed. The seedlings of larch require abundant light ; and this
they do not always find beneath the old forest-growth. But
the Arolla pine (Pinus Cembra) finds the conditions of light
more favourable to its development. It sows itself abundantly
and develops vigorously ; so that under these special and rare
conditions, the forest of Arolla pine will succeed the forest
of larch without the intervention of man (cf. Flahault and
Schroter, 1910; Rubel, 1911). However, no such explanation
as this is applicable in the present district.

A matter which, in my judgment, is not as a rule sufficiently
emphasized by plant geographers and foresters is that, in a
closed plant community, seedlings, especially seedlings of plants
with large seeds such as the oak and beech, are rarely found.
On the other hand, open and (to a less extent) intermediate
associations, if the general life-conditions are favourable, permit
of invasion and rejuvenescence. For example, the elms near
Cambridge produced an excessive quantity of fertile seeds in
the summer of 1909. Many of these seeds germinated on more
or less bare patches of soil, but not on the adjoining closed
pasture-land. It follows that a wood whose carpet is fully
occupied by closed ground societies does not tend to rejuvenate
itself; and, as the more upland ash, oak, and birch woods of

Ill] SCRUB ASSOCIATIONS 93

this district are, on the whole, characterized by such closed
ground societies, it would seem that here is an additional reason
which helps to explain the gradual degeneration of the forests
of the Pennines. It is difficult, for example, to see how a close
turf of silver hair grass (Deschampsia flexuosa) can be colonized
by oak or beech seedlings; and, in fact, such seedlings are rarely
seen in these situations. This fact is known to some foresters
of the country ; and use is made of their knowledge in that
many of the woods and plantations of which they have charge
have the ground kept more or less free of woodland " weeds."

The difficulty which larch seeds experience in germinating
in closed herbage in the larch forests of the Altai Mountains has
been pointed out by Krassnoff (1886) and quoted by Warming
(1909: 316): "the herbaceous vegetation consists of species
of Aconitum, Delphinium, Paeonia, Clematis, and others. Each
year millions of larch seeds fall into this sea of herbage ; yet
only a few find places where they can germinate : the forest is
apparently doomed to extinction."

The remarkable series of climatic changes within the
historical period, which are invoked by certain writers to
account for plant-successions, are always open to a certain
amount of suspicion. In general, plant-successions, which have
taken place since early post-glacial times and in a region of
fairly uniform present-day climate, would seem to be explicable
by changes in the physiographical and edaphic conditions of
plant habitats.

DISTRIBUTION AND CHARACTER OF THE EXISTING SCRUB

The existing woodlands, at their upper altitudinal limits,
often pass imperceptibly into open scrub. On many of the
hill-slopes of the remoter valleys, trees are more or less thinly
scattered about; and it is, in fact, not always easy to decide
whether or not a particular tract of vegetation should be con-
sidered scrub or poor woodland. Longdendale, Upper Derwent
Dale, and Upper Cressbrook Dale furnish excellent examples of
scrub. In some cases, the ground vegetation is grassy, in
others heathy undershrubs are abundant. In some cases, the
tallest plants are shrubs; and these sometimes form dense
thickets : in others, shrubs are absent, and the uppermost layer

VEGETATION OF THE PEAK DISTRICT

[CH.

is a very thin forest of more or less dwarfed and stunted trees.
In nearly all cases, however, the scrub of this district appears
to consist of retrogressive forest communities, and only rarely,
as, for example, on certain fresh and newly formed soils beneath
cliffs, of scrub progressing towards mature woodland. In the
retrogressive scrub, a n amber of the more hardy ground species
of woods still persist, such as the wood-rush (Luzula pilosa), the
wood vetch ( Vicia sepium), Lathyrus montanum, the wood violet
(Viola Riviniana), the cow-wheat (Melampyrum montanum),
and the ubiquitous bracken (Pteris aquilina); but their
ultimate extinction, except perhaps in the case of the bracken,
as the woodland or scrub vegetation degenerates still further
towards grassland or heath or moor, appears certain.

Several of these areas still retain. the place-name "wood,"
although now the name is most inappropriate; but as such
areas occur within the primitive woodland zone, on more or
less sheltered slopes often near the head of the cloughs
(cf. figure 12) and dales (cf. figure 13), there need be no doubt
that the place-name really indicates the former nature of the
vegetation. It would appear to be true that, in districts which
are capable on climatic and edaphic grounds of supporting
woodland or true forest, the majority of the examples of open
scrub are to be regarded as degenerate woods and as retro-
gressive associations. A study of numerous examples of such
associations leads to the conclusion that the following succes-
sions have occurred and are still occurring in this district:

Succession I

Succession II

Succession III

Succession IV

Oak and birch

Ash woods on

woods on sand-

woods on rocky

woods on steep

limestone slopes

stone plateaux

sandstone slopes

shaly slopes

Scrub

.. 1

Siliceous grass-
land and heather

Siliceous grass-
land (with Mo-

Siliceous grass-
land

Calcareous
grassland

linia)

Moors

Ciipijriijlit

Figure 13.

A streamless Limestone Dale.

Calcareous grassland of sheep's Fescue-grass (Fextuca oi-ina) in the

foreground and on the right. Scrub of Hawthorns (Crataegus

Oxyucantha = C. monogyna) on the left. The dale is streamless,

and fenced with limestone walls.

Ill] SCRUB ASSOCIATIONS 95

Examples of Succession I occur on some of the Coal-
measure plateaux on the eastern Pennines at an altitude of
about 800 feet (244 m.), of Successions II and III in the cloughs
of the sandstones and shales (cf. figure 12), and of Succession IV
in the limestone dales (cf. figure 13).

The " scrub " of Crump (1904 : xxxviii), the " clough thicket"
of Smith and Moss (1903: 387), the "gill wood" and the
"hazel copse" of Smith and Rankin (1903 : 159 and 173), and
the " ash copse " of Moss (1907 a : 44) are here included in the
term scrub which is regarded as the English equivalent of the
German " gebusch."

Professor Diels (in Flahault and Schroter, 1910 : 19) con-
siders the use of vernacular names in plant geography very
questionable. He maintains that such terms are ambiguous
even in the language to which they belong, that to foreigners
they are either meaningless or liable to misunderstanding, that
even if such terms be once strictly defined they will become
confused again, that they are permanently confusing to people
unversed in phytogeography, that newly coined expressions
(e.g., "Hochmoor" and "high moor") are not truly indigenous
terms and are most confusing to non-specialists, and that it is
therefore desirable to have universal expressions in Latin or
Greek, and to have these alone. With Diels' general position
I have very much sympathy ; but it is quite impossible, even
if it be desirable, to abolish vernacular terms even when these
do lead to some confusion. Diels specially singles out the
English term " scrub " as a phytogeographical nomen confusum ;
and to this might be added the English terms "forest1,"
"heath2," and "swamp," and perhaps indeed every popular
physiographical and phytogeographical term. It appears to me
that the only course to adopt is to use vernacular names in
the most frequently accepted sense, and, in addition, to use
universal names which are not capable of misunderstanding.

1 "Forest," in English, may signify almost any wild, open, uncultivated
tract of land, not necessarily a tract of woodland, though historical documents
prove that parts, at least, of the ancient British forests were tree-clad at some
earlier period.

2 Although, in English, a heath is usually a heather-clad tract of land, yet,
in eastern England, the term is also used to denote a tract of calcareous pasture
with no heather, as Newmarket Heath and Boyston Heath ; and in Somerset,
it is used to designate tracts of deep and often wet peat.

96 VEGETATION OF THE PEAK DISTRICT [CH.

SCRUB IN OTHER DISTRICTS

Clements (1905: 287) has maintained that "in forests,
while many vegetation forms can still enter, none of these
produces a reaction sufficient to place the trees at a disadvantage ;
and the ultimate forest stage, though it may change in com-
position, cannot be displaced by another." If my contention
in the previous section of this chapter be sound, it follows that
this generalization of Clements is not of universal application.
In this district, and indeed in very many other districts, it would
appear to be indubitable that woodland is frequently displaced
by associations of scrub, grassland, heath, and moor. In all parts
of the British Islands, there has, within the historical period,
been a pronounced diminution of the forest area, a diminution
which, in my judgment, is in addition to and apart from any
artificial disforestation or any change of climate. The decay
of forests in central Europe and the conversion of many of
them into grassland and heaths is admitted by most phyto-
geographers ; and there are not wanting authorities who have
gone so far as to assert that prairies and even steppes have
been derived from pre-existing forest (cf. Warming, 1909 : 282),
though it is difficult to accept this view, especially with regard
to the origin of climatic steppes. In practically all cases of the
ascertained conversion of forest into grassland, it would seem
certain that an intermediate stage of open scrub occurred. It
has also been urged by some plant geographers that some
tropical forests have degenerated into savana-forest and scrub ;
and whilst this degeneration must obviously be accelerated by
a diminishing rainfall, it is by no means improbable that the
retrogressive succession may also take place in districts where
such a decrease is imperceptible. In Great Britain, the con-
version of woodland into scrub, and of scrub into grassland,
heath, or moor is seen not only on the Pennines, but in Wales,
in the Lake District, and in Scotland; and some of these
districts have a mean annual rainfall of 80 inches (203 cm.)
and occasionally more. Such successions are not exceptional
in this country, but widespread and general ; and whilst they
are without doubt often due, in part, to artificial causes, it is at
least conceivable that this is not always and wholly the case.

Ill] SCRUB ASSOCIATIONS 97

In districts where the rainfall is low, as on the borders
of steppes and at very high altitudes, where the amount of
precipitation is insufficient to permit of the growth of large
trees, there can be no doubt that static, climatic scrub occurs ;
and, on certain very dry soils in moderately rainy localities,
it is also certain that static, edaphic scrub occurs.

The relations of the most important types of scrub are
shown in the following scheme : —

Scrub

Kinetic Static

(1) Retrogressive (2) Progressive (3) Edaphic (4) Climatic

Of these, the examples of scrub met with in the Peak
District belong mostly to the first type; and no doubt the
great majority of the British examples of scrub should be
placed in the same class.

RELATION OF THE GROUND VEGETATION OF WOODLAND
TO RETROGRESSIVE SCRUB

Although nearly all the examples of scrub on the Pennines
belong to the retrogressive type, they are important, and no
account of the vegetation of a district which failed to account
for them, could be regarded as complete. At the same time, it
does not appear to be reasonable to regard subordinate asso-
ciations such as retrogressive or progressive scrub as of the
same ecological rank as chief associations like flourishing
tracts of woodland.

From the standpoint of succession, the study of the ground
vegetation of woodland is a matter of prime importance both
to the phytogeographer and to the forester. By such a study,
an inkling may be gained of the possible fate of particular
tracts of degenerating forest. For example, where the ground
vegetation consists of heathy undershrubs, such as bilberry
(Vacdnium Myrtillus) and heather (Galluna vulgaris), and of
humus-loving grasses, such as purple moor-grass (Molinia
caerulea) and silver hair-grass (Deschampsia flexuosa), it may

M. 7

98 VEGETATION OF THE PEAK DISTRICT [CH.

often be inferred that the wood is on its way towards heath or
nioor; whilst where the ground vegetation consists largely of
wood soft-grass (Holcus mollis), the wood is more likely to be
converted ultimately into grassland. On the other hand, a
wood whose ground vegetation consists largely of shade-loving .
species, such as wood anemone {Anemone nemorosa) and wood-
ruff (Asperula odorata), shows no signs of degeneracy and is
probably in a more or less static condition.

PROGRESSIVE AND RETROGRESSIVE SCRUB

Retrogressive scrub is so-called because it results from
the degeneration of chief associations (see p. 21). Progressive
scrub, on the other hand, leads to the establishment of chief
associations. As has been stated, the latter type of scrub is of
uncommon occurrence in this district. However, small examples
of progressive scrub may be seen here and there. They are
found on fresh soils at the base of cliffs, on projecting ledges of
cliffs, on screes, and in deserted quarries. On the sandstones
and shales, in fact, they are almost limited to the last kind of
locality. Mr Margerison (1907 — 8) has published an excellent
account of the vegetation of sandstone quarries near Bradford,
Yorkshire ; and his account is of more than local interest.
Mr Margerison shows that the plant succession of some of the
disused sandstone quarries which he investigated has reached
the stage of a birch (chiefly Betula pubescens) wood ; and it is
possible that this stage may in time be replaced by a wood of
Quercus sessiliflora. On the limestone areas, however, the
culminating stage is an ash (Fraxinus excelsior) wood. Retro-
gressive scrub is usually open : progressive scrub is frequently
closed, and often forms dense impenetrable tangles of low
woody vegetation.

COMPARISON OF THE TYPES OF RETROGRESSIVE SCRUB

The different types of scrub of the district, then, are
related to chief associations of woodland. The decay of oak
and birch woods results in types of scrub which should be classed
in the same plant formation as the oak and birch woods ; and
the decay of ash woods results in types of scrub which should

Ill]

SCRUB ASSOCIATIONS

be placed in the same plant formation as the ash woods.
There is, so far as one can judge, little or no essential change
in the essential nature of the habitats of the various woods and
their related scrub; and intermediate examples are so very
numerous and varied that it would seem to be quite impossible
to decide on any natural line of demarcation between woodland
and related scrub.

In subordinate associations such as these, which are "on
the move," i.e., which are kinetic and not static, it is a difficult
matter to give really satisfactory lists of plants. If the
localities are not very carefully chosen, one finds, in the case of
scrub, for example, that one takes a list of species almost
characteristic of a wood or a list almost characteristic of grass-
land. The following lists, however, are taken from typical
cases of scrub, though another observer might easily include
either more woodland species or more grassland species. As it
is, it will be seen there are very few species of the scrub which
do not occur either in the woodland or grassland associations ;
and from this point of view alone, it is not possible to regard
the different types of scrub that occur in this district as consti-
tuting a natural group of plant communities.

Scrub on
sandstone
plateaux
and slopes

Scrub on
shaly
slopes

Scrub on
limestone
slopes

Trees, shrubs, and undershrubs

Salix caprea

S. caprea x cinerea

S. cinerea

var. aquatica

—

var. oleifolia

S. aurita

—

S. aurita x caprea

—

S. aurita x cinerea

— /

S. repens

—

Corylus Avellana

la to 3

Betula pubescens

r to a

—

var. parviflora

—

forma denudata

—

Quercus sessiliflora

r to o

—

Pyrus Malus

r to o

P. Aucuparia

7—2

100

VEGETATION OF THE PEAK DISTRICT

[CH.

Scrub on
sandstone
plateaux
and slopes

Scrub on
shaly
slopes

Scrub on
limestone
slopes

Trees, shrubs, and undershrubs

Pyrus Aria

—

Crataegus Oxyacantha

la to s

Rubus fruticosus (agg.)

r to a

Rosa canina

r to o

"R. mollis"

R. tomentosa

R. spinosissima

—

Prunus spinosa

r to o

Ulex Gallii

r to a

r to o

U. europaeus

—

Empetrum nigrum

r to o

—

Ilex Aquifolium

r to o

Euonymus europaeus

—

Rhamrius Frangula

—

R. catharticus

—

Hedera Helix

Cornus sanguinea

—

Calluna vulgaris

Erica Tetralix

—

E. cinerea

Vaccinium Myrtillus

r to o

—

V. Vitis-idaea *

Fraxinus excelsior

—

r to a

Lonicera Periclymenum

Herbaceous species

Nephrodiura montanum

( = N. Oreopteris)

r to o

—

N. Filix-mas

var. paleaceum

—

N. aristatum

r to o

Asplenium spp.

—

Blechnum 'spicant

—

Pteris aquilina

r to a

Rumex Acetosella

Lychnis dioica

Stellaria Holostea

r to o

Thalictrum collinum

Anemone nemorosa

r to o

Ranunculus bulbosus

R. Ficaria

r to la

Corydalis claviculata

Canlarnine impatiens

—

Sedum acre

Saxifraga hypnoides

—

S. tridactylites

—

Rubus saxatilis

—

Ill]

SCRUB ASSOCIATIONS

101

Scrub on
sandstone
plateaux
and slopes

Scrub on

shaly
slopes

Scrub on
limestone
slopes

Herbaceous species

Fragaria vesca

—

r to o

Potentilla erecta

Poteriurn Sanguisorba

—

Alchemilla filicaulis

—

Agrimonia Eupatoria

—

Lathyrus montanus

r to o

Geranium sanguineum

—

Oxalis Acetosella

Polygala vulgaris

—

r to a

P. serpyllacea

Mercurialis perennis

—

r to a

Hypericum pulchrum

H. perforation

—

r to o

H. hirsutum

—

r to la

H. rnontamim

—

Helianthemum Chamaecistus

—

Viola hirta

—

V. Riviniana

r to o

Epilobium montanum

—

E. angustifolium

Conopodium majus

—

r to o

Heracleum Sphondylium

—

Daucus Carota

—

Pyrola media

—

P. minor

—

Primula veris

—

P. vulgaris

r to o

Gentiana Amarella

—

Teucrium Scorodonia

r to o

Scutellaria minor

—

Nepeta hederacea

—

Origanum vulgare

—

o to a

Thymus Serpyllum (agg.)

—

o to a

Veronica officinalis

—

r to o

Digitalis purpurea

—

Melampyrum pratense (agg.)

—

Plantago media

—

P. lanceolata

—

r to o

Galium verum

—

G. Cruciata

—

r to o

G. saxatile

o to a

—

G. sylvestre

—

Scabiosa Succisa

S. Columbaria

—

Campanula Trachelium

—

C. rotundifolia

r to o

Jasione montana

—

102

VEGETATION OF THE PEAK DISTRICT

[CH. Ill

Scrub on
sandstone
plateaux
and slopes

Scrub on
shaly
slopes

Scrub on
limestone
slopes

Herbaceous species

Solidago Virgaurea

—

r to o

Antennaria dioica

—

Gnaphalium sylvaticum

—

Inula squarrosa

—

Chrysanthemum Leucanthemum

—

r to a

Senecio sylvaticus

—

Carlina vulgaris

r to o

Carduus nutans

—

r to o

Cnicus eriophorus

—

C. palustris

Centaurea Scabiosa

—

r to o

Picris hieracioides

—

Leontodon hispidus

' —

Hieracium spp.

r to la

Taraxacum officinale (agg.)

—

Anthoxanthum odoratum

Agrostis tenuis

( = A. vulgaris)

Holcus mollis

r to o

—

Deschampsia flexuosa

—

Avena spp.

—

r to o

Arrhenatherum elatius

—

vr, 1

Triodea decumbens

r to o

Molinia caerulea

—

Koeleria cristata (agg.)

—

Melica nutans

Briza media

—

Festuca ovina

r to o

Brachypodium sylvaticum

—

r to a

Carex binervis

r to o

—

C. pilulifera

C. ornithopoda

—

Juncus spp.

Luzula multiflora

o to a

—

forma congesta

—

L. campestris

—

L. pilosa

r to o

Convallaria majalis

—

Scilla non-scripta

—

Listera ovata

—

r to o

Helleborine atrorubens

Habenaria viridis

"Ophyrs apifera"

—

Orchis mascula

r to la

"0. pyramidalis"

—

CHAPTER IV

GRASSLAND ASSOCIATIONS

Distribution of the grassland. Types of grassland. I. Grassland of the
sandstones and shales: siliceous grassland; (1) Nardus grassland ;
mixed siliceous grassland ; (2) Molinia grassland. Relationships of
the plant associations of the siliceous soils. II. Grassland of
the Limestone : calcareous grassland : mixed calcareous grassland ;
transitional calcareous grassland. Calcareous heath. Pseudo-cal-
careous heaths. Species of the calcareous grassland and the siliceous
grassland. Relationships of the plant associations of the siliceous
and the calcareous soils.

DISTRIBUTION OF THE GRASSLAND

As is the case with woodland and scrub, grassland occurs, in
general, on the slopes of the hills. Where the hill-slopes below
about 1500 feet (457 m.) are not cultivated and not occupied
with woodland or scrub, there natural or uncultivated grassland
prevails. The cultivated grassland or permanent pasture is
dealt with in Chapter VIII. On the whole, natural grassland
is more extensive on the limestones than on the sandstones
and shales; and, with regard to the non-calcareous soils, it is,
in proportion to their extent, much more extensive on the shales
than on the sandstones.

At the present time, although grassland ascends to higher
altitudes than the woodland, it is rather rare at altitudes above
the present limit of scrub. It is highly probable that almost
all the present grassland — both natural and cultivated — was
once wooded, and that even now it is almost all capable of being
successfully reaff crested (see Chapter VIII).

104 VEGETATION OF THE PEAK DISTRICT [CH.

In a few places, however, as on the elevated summit of
Bleaklow Hill, at a height of about 2000 feet (610 m.), sub-
Alpine grassland occurs on ground which has probably never
been tree-clad — at least, not in post-Tertiary times. It will be
shown later on that such sub- Alpine grassland occurs, so far as
this district is concerned, on sites which were comparatively
recently covered with peat; and the peat having suffered
denudation, plants of the siliceous pasture have successfully
invaded areas which were once peat-clad.

Natural grassland is rather uncommon on the less elevated
plateaux, for these are usually either occupied by moorland
associations or they are under cultivation.

TYPES OF GRASSLAND

Two main types of grassland occur in the district. One is
developed on the siliceous soils, the other on the calcareous
soils. The former type of grassland is characterized by the
great abundance of heath-loving or humus-loving species, and is
termed siliceous grassland. The non-calcareous or siliceous soils
allow of the formation and accumulation of acidic humus in the
soil ; but any great excess of this is, on steep slopes, prevented
by the denuding action of rain and melting snow. Instead of
the accumulation of peat, we get, on steep slopes, a slow but
continuous exposing of new soils. Such conditions favour the
growth of sward-forming grasses rather than of heathy under-
shrubs, for although newly exposed siliceous soils are much
poorer in soluble minerals than calcareous soils, they are richer
than sour peaty soils. On the plateaux, however, the acidic
humus or peat may accumulate ; and the ground is then invaded
by heather (Galluna vulgaris) and ecologically allied species. It
seems certain that the steep shaly slopes will never become
peat clad, whilst the grassland of the non-calcareous plateaux
will probably be ultimately converted into moorland.

The sub-Alpine pasture above mentioned is essentially
identical in its ecological and floristic characteristics with
siliceous pasture; but, as it occurs at higher altitudes, it has
fewer associated species. All the species, however, which
actually occur on the sub-Alpine pasture, occur on heath
pasture also; and the two associations therefore are placed

Figure 14.

W. 1>. Cnunp

Siliceous Grassland.

Blue moor-grass (Molinia caerulea) in the foreground. Mat-grass

(Nardus stricta) and silver Hair-grass (Deschampsia flexuosa)

covering the whole of the slopes and summit of the hill.

IV] GRASSLAND ASSOCIATIONS 105

in the same plant formation. On the Pennines further north
(see Smith and Rankin, 1903: 154), similar sub- Alpine pasture
occurs; but there one species, Poa alpina, occurs which has
not been found in the Peak District. Sub- Alpine pasture,
characteristic of the Scottish mountains, has been described
by R. Smith (1900 b : 454).

On the calcareous soils, the grassland is poor in heath-loving
or humus-loving species but rich in lime-loving species, and this
association is termed calcareous grassland. A certain number
of species (see the lists of plants given later on in the chapter)
are common to siliceous grassland and calcareous grassland.
The two types of grassland are related, directly or indirectly, to
the presence or absence of calcium carbonate in the soil. On
the limestones, it is only at the higher altitudes, where the soils
are leached by rain and therefore contain much less lime, that
calcareous grassland approaches siliceous grassland in its eco-
logical and floristic characteristics. On the lower slopes of the
calcareous hills where the soil is rich in lime, the acidic
humus which favours the growth of the plants of the siliceous
grassland does not appear to be formed ; and it certainly does
not accumulate.

A certain amount of grazing of sheep and cattle takes
place on many parts of the grassland ; but the amount is, on
the whole, rather small. The land is not artificially manured
or drained. On the sub-Alpine grassland, no grazing or
manuring takes place at all.

Other types of grassland occur in other parts of the country,
more especially in central and southern England. Clayey and
fresh loamy soils, for example, are characterized by the absence
of both humus-loving and of lime-loving species; and the
grassland of such soils may therefore be termed neutral grass-
land. A fourth type occurs on the flat lands which occur near
rivers and which are liable to periodical inundations : this may
be termed alluvial or fen grassland. An analysis of ' the
grasslands of Orkney has recently been published (Scarth,
1911).

" Permanent pasture " is an agricultural term in use in
this country to denote grazing land which has, in general,
been ploughed up at least once, and which is artificially
manured (see Chapter VIII).

106 VEGETATION OF THE PEAK DISTRICT [CH.

I. GRASSLAND OF THE SANDSTONES AND SHALES:
SILICEOUS GRASSLAND

Two types of siliceous grassland have been described in
previous botanical surveys of the Pennines (Smith and Moss,
1903 : 384 ; Smith and Rankin, 1903 : 158 ; Lewis 1904 a : 323,
1904 b : 275), and have been distinguished as wet and dry.
The most abundant and characteristic grass of the drier type
of siliceous grassland is the mat-grass (Nardus stricta) and
that of the wetter type is the purple moor-grass (Molinia
caerulea) (cf. figure 14). The two species are respectively
dominant in the two associations since they nearly monopolize
the ground and form the great bulk of the turf, the asso-
ciated species being therefore more or less controlled by them.
The former association may therefore be termed Nardus grass-
land (Nardetum strictae) and the latter Molinia grassland
(Molinietum caeruleae). To some extent, the associations are
layered plant communities; and the smaller plants receive a
certain amount of shade and shelter from the dominant ones.
As is usual in plant associations, one or another of the
dependent species occasionally becomes more or less social;
and thus plant societies and facies arise.

(1) Nardus Grassland

Typical Nardus grassland (see figure 13) occurs on steep
shaly slopes of the non-calcareous hills. In summer, this
association is characterized by a grassy turf, grey-green in
colour, dry and slippery. In late autumn, winter, and early
spring, the ground is damp and sodden; and the bleached
haulms of the mat-grass (Nardus stricta) give tone to the
landscape, and may be recognised at a considerable distance.
The silver hair-grass (Deschampsia flexwsa) is, in this district,
a constant associate. In winter, the mat-grass is very much
more conspicuous than the hair-grass, as, during this season,
the short leaves of the latter are usually more or less hidden
beneath the long, white sprays of the dead shoots of the former.
Under such conditions, the hair-grass, even though very
abundant, is apt to be overlooked. It is only in early summer,
when the tall, purple scapes of the hair-grass are in bud, flower,

IV] GRASSLAND ASSOCIATIONS 107

or fruit that this species becomes obtrusively conspicuous ; and,
at such times, it gives the tone and colour to the whole
association. There seems little doubt, however, that the
Nardus association of the Peak District is ecologically identical
with that of the Wicklow Hills (Pethy bridge and Praeger,
1905: 157) and that of the northern Pennines (Lewis, 1904 a:
324; 19046: 275), even though the silver hair-grass is not
included in the lists of these districts.

The silver hair-grass of the hills of the Peak District
belongs to the form with short, wiry, and sub-squarrose leaves
(Deschampsia flexuosa, ? var. montana) : the form in the oak and
birch woods has much longer, more limp, and more slender
leaves. Woodhead (1906 : 383) has described and figured the
structural differences of some of the forms of this plant.

The two grasses (Nardus stricta and Deschampsia flexuosa)
remain co-dominant up to the edge of the moorland plateau,
which frequently occurs at about 1500 feet (457 m.). Below
about 1250 feet (381 m.), the common bent-grass (Agrostis
vulgaris) is often an abundant associate, giving rise to a distinct
facies. In the late summer months, its delicate and purple
panicles colour the hill sides. As lower altitudes are approached,
this species becomes increasingly abundant at the expense of
the mat-grass (cf. page 112). The sheep's fescue-grass (Festuca
ovina) is also often associated ; and this species sometimes forms
plant societies and facies.

The shaly hill-slopes of the Pendleside (or Yoredale) series
which encircle the upper Edale valley afford an extensive and
continuous expanse of Nardus pasture. On the north of this
upland valley are the slopes of the Peak, on the south the
slopes of the Mam Tor range, and on the east the slopes of the
Colborne moors. Such a great expanse of Nardus grassland is
not seen elsewhere in the district. In the sheltered Grindsbrook
clough, the bracken (Pteris aquilina) asserts itself very strongly:
the dwarf furze ( Ulex Gallii) occurs in small patches here and
there ; and the springs of water on the hill sides are marked by
clumps of the common rush (Juncus effusus).

The last three species give to the association very different
aspects or facies. The bracken, where the soil is dry and the
locality sheltered, sometimes occurs in extensive sheets (see
figure 15). The gorse (Ulex Gallii) is never very prominent in

108 VEGETATION OF THE PEAK DISTRICT [CH.

this district, like it is, for example, on the Malvern Hills or on
the Wicklow Hills (cf. Pethybridge and Praeger, 1905: 153,
plates 7 and 8); but it occurs in patches in dry and fairly
exposed localities. The rush (Juncus effusus and /. effusus forma
compactus), in damp places, and independently of conditions of
shelter or exposure, is an abundant and characteristic associate.
The bracken and the rush, in fact, are, in many places harvested
by the upland farmers (see figures 15 and 16).

The relationships of the various facies and aspects of
the Nardus association may be indicated diagrammatically
as follows : —

NARDETUM STRICTAE

Facies of
Agrostis vulgaris

Facies of

. Deschampsia flexuosa

Facies of Facies of Facies of S,

Ulex Oallii Pteris aquilina Juncus effusus

The bracken facies (see figure 15) and the rush facies
(see figure 16) are very well developed in this district. For
example, in ascending Longdendale (above Glossop), one meets
with Nardus grassland on the hill-slopes. The bracken here
varies from being a rare member of the association to a
subdominant member. However, the general habitat conditions
seem so very constant, and the bracken itself so very variable in
amount in different parts of the association (even within quite
small areas), that it seems impossible to regard the bracken
as modifying the association any more than producing a facies.
Towards the head of Longdendale, between Woodhead and
Dunford Bridge, the bracken becomes less general ; whilst the
rush becomes a normal and an abundant member of the
Nardus grassland. Such places are always ill-drained; and
from them, the gorse and the bracken are invariably absent.
The cotton-grass (Eriophorum angustifolium) sometimes occurs.
Such a Juncus facies of siliceous grassland must be distin-
guished from the Juncus swamp (Juncetum effusi) described in
Chapter VI.

The bracken is one of the most accommodating of plants as
regards its requirements. It is present in nearly all woods,
except in the shadiest, dampest, and most calcareous places;

Figure 15.

ir. i'.

Siliceous grassland.

Facies of Bracken (Pteris aquilina). Stack of bracken litter in the fore-
ground. The trees are Hawthorns (Crataegus Oxi/acantha — C. monogyna).

IV] GRASSLAND ASSOCIATIONS 109

and it is probable that the present upper altitudinal limits of
the bracken approximate very closely with the upper altitudinal
limits of the ancient and pre-historical forests. Sometimes the
bracken spreads from the Nardus grassland into the adjoining
moorland associations, not uncommonly into the heather
(Calluna vulgaris) moor when this occurs in rather sheltered
valleys and depressions, and rarely into the cotton-grass
(Eriophorum vaginatum) moor when the peat of this is be-
coming drier. In the Peak District, the bracken commonly
ascends to 1500 feet (457 m.) or 1550 feet (472 m.), above which
altitudes it becomes local and rare. Woodhead (1906 : 360)
states that it ascends to 1700 feet (518 m.); but in England
it is quite exceptional to meet with the plant at such an
altitude.

Pethybridge and Praeger (1905 : 155) describe areas of
bracken in the district south of Dublin. The list of species
which these authors give indicates that species characteristic of
Nardus grassland are numerous in such areas. The authors
state that in the month of May, the bracken areas often exhibit
glorious sheets of blue, white, and yellow due to the abundance
of the blue-bell (Scilla non-scripta), violet (Viola Riviniana),
speedwell (Veronica Chamaedrys), earth-nut (Conopodium
majus), lesser celandine (Ranunculus Ficaria), and primrose
(Primula vulgaris). Such a display of flowers is unknown in
connection with the bracken areas of the upland slopes of
the Pennines, but may occasionally be seen as the lowlands are
reached.

Pethybridge and Praeger (1905: 150 and 153) map two
plant communities of gorse. In one, at lower altitudes, Ulex
europaevs is conspicuous ; and in the other, at higher elevations,
Ulex Oallii is exceedingly abundant. In this district, the two
species have similar altitudinal relationships ; but they are not
specially abundant, especially U. europaeus. In Somerset,
this altitudinal relationship perhaps does not hold good, ' for
the two species frequently occur side by side. In certain
localities in the south of England, a third species of gorse
( Ulex minor = U. nanus) becomes locally a very important
element on heaths and heathy grasslands.

Ostenfeld (1908: 966) has described a grass-slope "forma-
tion " of the Faeroes ; and this would appear to be very closely

110 VEGETATION OF THE PEAK DISTRICT [CH.

related to the siliceous grassland of Britain, as about eighty per
cent, of the species are common to the two types of vegetation.
Brockmann-Jerosch (1907 : 248, etc.) has described an
association (Bestandetypus) of Nardus stricta in the Puschlav
region of the Swiss Alps. This Alpine Nardetum is found at
much higher altitudes than occur anywhere in England, and
contains many species which are not indigenous in this country :
still, about thirty per cent, of the species given by Brockmann
(1907 : 305 — 8) are found in the Nardetum of the Peak District
of Derbyshire ; and probably the two associations should be
placed in the same plant federation (see Moss, 1911), but in
different geographical plant formations. The elements common
to the two associations are the following :—

Botrychium Lunaria .Achillaea Millefolium

Rumex Acetosella Hieracium Pilosella

Ranunculus acris Anthoxanthum odoratum

Trifolium repens Deschampsia flexuosa

T. pratense Sieglingia decumbens

Vaccinium Vitis-idaea Nardus stricta

Calluna vulgaris Carex caryophyllea

Antennaria dioica Luzula campestris

It has already been emphasised that the woods of the
district gradually pass into scrub; and similarly the scrub
imperceptibly passes into grassland. Just as there are many
localities which are difficult to determine either as woodland or
scrub, so there are many other places which are difficult to
determine either as scrub or grassland. Again, whilst much of
the scrub represents degenerate woodland, much of the grassland
represents a still later stage of degeneracy than the scrub.
There can be little doubt that the hill-slopes now characterized
by grassland were, generally speaking, once wooded ; and it is
highly probable that most of these slopes are capable of being
successfully re-afforested. In the Nardus grassland on the hill-
slopes of this district, the following woodland species, among
others, still linger here and there: —

Pteris aquilina Betula pubescens

Nephrodium montanum Lychnis dioica

N. aristatum Corydalis claviculata

N. Filix-mas Oxalis Acetosella

Athyrium Filix-foemina Geranium Robertianum

Quercus sessiliflora Ilex Aquifolium

Figure 1C.

Siliceous grassland.

Fades of the common Rush (Juncus efl'usua).
Hal-vestals' the rushes.

W. B. Crump

IV] GRASSLAND ASSOCIATIONS 111

Pyrus Aucuparia Ajuga reptans

Crataegus Oxyacantha Digitalis purpurea

Lathyrus montanus Melampyrum pratense (agg.)

Vicia sepium Holcus mollis

Viola Riviniana Luzula pilosa

Conopodium denudatum Orchis mascula

Heracleum Sphondylium Scilla non-scripta

Whilst opinions may differ as to whether or not the
grassland just described is wholly or only in part due to man's
interference, it appears to be generally accepted that such tracts
were formerly clothed with forest; and Warming (1909: 326)
even goes so far as to say that " were the human race to die out,"
the grasslands of the lowlands of north Europe "would once
more be seized by forest, just as their soil was originally stolen
from forest." As regards the Nardus grassland of the hill-slopes
of this district, it seems incontestable that it is an association
which has, on the whole, resulted from the degeneration of oak
and birch woods. The fundamental conditions of the habitat
have been but slightly altered in the process; and, therefore,
the oak and birch woods, the Nardus grassland, and the various
transitional stages of scrub are placed in one and the same
plant formation.

The following is a list of the more typical and abundant
plants which occur in the Nardus grassland : full lists of grass-
land species are given at the end of the chapter : —

Dominant species
Nardus stricta

Sub-dominant species
Deschampsia flexuosa

Locally sub-dominant species
Pteris aquilina

Locally abundant species

Ulex Gallii Festuca ovina

Agrostis vulgaris Juncus effusus

Less abundant and rarer species

Botrychium Lunaria (local) Potentilla erecta

Blechnum spicant Lotus corniculatus

Rumex Acetosella Cytisus scoparius

112

VEGETATION OF THE PEAK DISTRICT

[CH.

Lathyrus montana
Polygala serpyllacea
Hypericum pulchrum
Viola lutea (local)
Veronica officinalis
Euphrasia officinalis (agg.)
Plantago lanceolata
Qalium saxatile
Campanula rotundifolia

Crepis virens
Hieracium Pilosella
Anthoxanthum odoratum
Briza media
Carex flacca
C. binervis
C. pilulifera
Juncus squarrosus
Luzula erecta

Mixed Siliceous Grassland

Bordering on the upper limits of the cultivated land on
rough escarpments of the cloughs, and on the outskirts of
woods, a type of siliceous pasture occurs which is much
richer in associated species than the Nardetum just described.
The type of siliceous pasture here referred to is found usually
at altitudes below 1000 feet (305 m.), is frequently fenced, and,
to some extent, is grazed over by cattle; but it is probable that
it has never been ploughed or drained. Many of the species
are of local occurrence, and probably represent the remains of a
primitive flora which flourished in the open spaces of the
aboriginal woods at comparatively low altitudes. The flora of
this association has been given by Crump (1904: xli) and by
Smith and Moss (1903 : 385), so far as the Leeds and Halifax
district is concerned.

The following list illustrates the wealth in species of this
type of siliceous grassland : —

Botrychium Lunaria
Ophioglossum vulgatum
Pteris aquilina
Blechnum spicant
Nephrodium montanum
Salix caprea
S. caprea x cinerea
S. aurita

S. aurita x caprea
S. aurita x cinerea
S. cinerea
S. repens

Betula pubescens (dwarfed)
forma denudata (dwarfed)
Corylus Avellana

la
rtola

lo
r to o

r
lo to la

r
rto lo

Quercus sessiliflora (dwarfed)

Rumex Acetosa

R. Acetosella

Ranunculus acris

R. bulbosus

Cerastium vulgatum

Stellaria graminea

Prunus spinosa

Rubus fruticosus (agg.)

Potentilla erecta

P. procumbens

P. erecta x procumbens

Alchemilla vulgaris (agg.)

Rosa canina

R. tomentosa

o
r to o

la
o to a

r
r to o

IV]

GRASSLAND ASSOCIATIONS

113

Pyrus Malus

P. Aucuparia (dwarfed)

Crataegus Oxyacantha

Genista anglica

G. tinctoria

Ulex Gallii

U. europaeus

Ononis repens

Trifolium medium

T. pratense

T. repens

Lotus corniculatus

Vicia angustifolia

Lathyrus pratensis

L. montanus

Linum catharticum

Polygala serpyllacea

Hypericum humifusum

H. pulchrum

Viola lutea

V. Riviniana

Empetrum nigrum

Ilex Aquifolium (dwarfed)

Pimpinella Saxifraga

Conopodium majus

Vaccinium Myrtillus

V. Vitis-idaea

Calluna vulgaris

Erica cinerea

Primula veris

Centaureum umbellaturn

Gentiana Amarella

G. baltica

Thymus Serpyllum (agg.)

Stachys omcinalis

Teucrium Scorodonia

Digitalis purpurea

Veronica omcinalis

V. Chamaedrys

Prunella vulgaris

Euphrasia omcinalis (agg.)

Bhiuanthus Crista-galli

Plantago lanoeolata

Galium saxatile

Scabiosa Succisa

S. arvensis

Campanula rotundifolium

Jasione montaua

Solidago Virgaurea

r to o

r
r to a

r, la

r to o
o
o
a
r
o
o
a
o
Ir
o

r,la

r, la

r to a

o to r

rtola
o
o
la
o
a

r, la
a
a
o
r

o to a

r to o

P»ellis perennis
Gnaphalium sylvaticum
Achillaea Millefolium
Chrysanthemum Leueanthe-
mum
Senecio Jacobaea
Carlina vulgaris
Centaurea nigra
Crepis virens
Hypochaeris radicata
Leontodon hispidus
L. autumnalis
Hieracium Pilosella
H. vulgatum
H. boreale
Taraxacum officinale

var. maculiferum
Anthoxanthum odoratum
Agrostis tenuis
Deschampsia caespitosa
D. flexuosa
Holcus molh's
H. lanatus

Arrhenatherum avenaceuui
Sieglingia decumbens
Cynosurus cristatus
Molinia caerulea
Briza media
Festuca ovina
F. duriuscula
Brachypodium sylvaticum
P. vulgaris
Carex ovalis
C. flacca
C. pilulifera
C. caryophyllea
C. hirta
C. pallescens
C. binervis
Luzula pilosa
L. campestris
L. erecta
Listera ovata
Orchis maculata
O. ericetorum
Habenaria conopsea
H. viridis
H. bifolia
H. chloroleuca

vr
o

o
la
vr

a
o to a

a to s
r to o
o to a

1
1

o to a
r to a.

r to o
r too

114 VEGETATION OF THE PEAK DISTRICT [CH.

(2) Molinia Grassland

The wetter type of siliceous grassland (cf. p. 106), dominated
by the purple moor-grass (Molinia caerulea), is of far less extent
in this district than the Nardus grassland, and much more local
in its occurrence.

The Molinia grassland occurs, as a rule, on flatter ground than
the Nardus grassland (cf. figure 14). In a very general way, the
Molinia grassland affects the ground overlying the sandstone
rocks and the Nardus grassland the steep slopes of the shales.
Occasionally, the Molinia grassland occurs on shales where the
drainage is obstructed by boulders which have fallen from an
escarpment of sandstone. Invariably, the soil of the Molinia
grassland is wet, often very wet, and more or less peaty. Such
soil is, in this district, always acidic; but Molinia is by no
means always confined to acidic soils. In East Anglia, for
example, Molinia occurs on alkaline peaty soils ; and here the
associated species are different from those of acidic soils. On
acidic soils, the Molinia grassland is transitional between grass-
land and moorland, as was recognised by R. Smith (1900 b :
454) ; and examples occur which might quite fairly be placed
among the moorland associations. The moorland character is
seen in its acidic peaty soil, often supersaturated with moisture,
and in the abundance of associated species which characterize
certain parts of the moorland. Some of the Molinia associa-
tions of this district are almost demonstrably derived from
oak or birch woods with a heathy ground flora; and there
can be little doubt that it sometimes develops into moorland.
Transitions of this nature occur on the south side of Longden-
dale, near Crowden railway station. In a few cases, perhaps,
Molinia invades the Nardus grassland ; and Molinia is frequently
an associate in the heather moor.

The plant (Molinia caerulea) has a wide range of form and
habitat. The variety of form known as Molinia caerulea var.
depauperata, with one-flowered spikelets and shorter leaves and
shoots, occurs in very wet places. Usually, the plant (Molinia
caerulea) is about half a metre high ; but here and there a
variety (M. caerulea var. major) with wide -spreading branches
of the inflorescence occurs. The plant is deserving of a careful

IV]

GRASSLAND ASSOCIATIONS

115

study on account of its wide range of forms and the different
nature of its habitats.

A list of the members of the Molinia grassland is appended,
and the number of associated species characteristic of the
moorland formation is obvious: —

Polytrichum commune

Nardus stricta

Sphagnum spp.

Scirpus caespitosus

r to o

"Lycopodium inundatum"

Eriophorum vaginatum

r to o

Ranunculus Flammula

E. angustifolium

forma radicans

r to a

Carex curta

r to o

Drosera rotundifolia

C. echinata

Viola palustris

r to o

C. Goodenowii

o to a

Empetrum nigrum

var. juncella

Hydrocotyle vulgaris

C. glauca

Andromeda Polifolia

C. panicea

o to a

Erica Tetralix

Deschampsia flexuosa

r to a

Calluna vulgaris

Carex flava

Vaccinium Myrtillus

var. minor

V. Oxycoccus

r to a

Juncus effusus

Pinguicula vulgaris

J. squarrosus

Taraxacum palustre

J. acutiflorus

Agrostis canina

Narthecium ossifragum

r to la

Molinia caerulea

a to d

Orchis maculata

var, depauperata

r to d

0. ericetorum

r to o

var. major

RELATIONSHIPS OF THE PLANT ASSOCIATIONS
OF THE SILICEOUS SOILS

The relationships of the plant associations of the sandstones
and shales of the southern Pennines are summarized in the
following table : —

Sandstone

rocks
and screes

'Woods of Betida pubescens
or of Quercus sessiliftora

Various stages of scrub

Molinia pasture

Nardus pasture

Swamps

Nardus pasture with much Calluna

I
[Moorland Formation]

8—2

116 VEGETATION OP THE PEAK DISTRICT [CH.

II. GRASSLAND OF THE LIMESTONE: CALCAREOUS GRASSLAND

In previous works on British plant geography, this group
of associations has been variously termed "natural pasture,"
"limestone hill pastures," and "Permian common" (cf. Smith
and Moss, 1903 ; Smith and Rankin, 1903 ; Lewis, 1904 a and b;
and Moss, 1907 a); but the name calcareous grassland is now
becoming general.

Typical calcareous grassland consists of short, grassy turf,
largely composed of the sub-aerial parts of the sheep's fescue-
grass (Festuca ovina). In this district, calcareous grassland is
found abundantly on the uncultivated, steep slopes of the lime-
stone dales (see figures 12 and 16). On the limestone plateaux,
the soil is frequently leached, and then certain plants of the
siliceous grassland enter the association.

It will be seen that the boundaries of the associations of the
soils of the sandstones and shales and of the soils of the lime-
stones do not follow any boundaries shown on the geological
maps. The latter indicate the boundaries and extent of the
subjacent rocks, but do not attempt to deal with the surface
soils which alone are related directly to the flora and vegetation.
This distinction between the subjacent rocks and the surface
soils is adequately emphasized in the treatment of plant
formations of the British Isles by Tansley (1911, passim).

With slight differences in floristic composition as are indi-
cated in the preceding paragraph, calcareous grassland occurs
on all the uncultivated tracts of the various calcareous soils of
the country, such as on the chalky boulder clay, the chalk rock
and marl, the Jurassic marls and limestones, the Permian or
Magnesium Limestone, and the Palaeozoic limestones.

Calcareous grassland is a plant association, or perhaps a
group of closely allied associations, characterized by the presence
of numerous lime-loving species and by the absence of heath-
loving or humus-loving species. Lime-loving species have been
variously termed xerophiles, calciphiles, and calcicoles: lime-
shunning species have been termed hygrophiles, calciphobes,
and silicicoles. It seems highly desirable to subdivide the
lime-avoiding species into three classes: — (1) plants of acidic
peat, (2) plants of siliceous soils, and (3) plants of sandy soils.

IV] GRASSLAND ASSOCIATIONS 117

The soil of the calcareous grassland of the limestone slopes is
shallow, sometimes not even an inch (about 2*5 cms.) deep. In
colour, it varies from a whitish grey when the lime-content is
very high, to brownish or even reddish-brown when the lime-
content is lower and the iron-content higher. At the foot of a
cliff, the soil may be a metre or more in depth : commonly it is
about a sixth to a third of a metre deep. The soil of lime-
stones is usually described as being very dry and porous ; but it
is only the newer and whiter soil of which this may correctly
be stated. The older and darker soil is of a marly nature, and
is neither specially dry nor specially porous. Similarly, the
newer and yellower soil of the sandstones may be dry and
porous, whilst the older and blacker soil of the sandstones is
retentive of water. Analyses prove that the range of variation
of water-content of the soils derived from the limestone rocks
is roughly paralleled by that of the soils of the sandstones and
shales. Just as the water-content of the non-calcareous soils
varies directly as the humus-content, so the water-content of
the limestone soils varies inversely as the lime-content. The
former result is doubtless due to the water-absorbing properties
of humus : the latter seems to be due to the fact that calcium
carbonate is dissolved by water containing carbon dioxide ; and
thus as limestone soils become older they lose more and more
lime and acidic humus then tends to accumulate. Marshy
places occur on the limestone just as they do on the sandstones
and shales. However, it may be said that, in general, such
localities are least frequent on the limestones, more frequent
on the sandstones, and very numerous on the shales. The
marshy places on the limestones bear a very different flora from
those of the sandstones and shales, just as the dry limestone
soils possess a very different flora from such soils on the sand-
stones ; and it thus appears to be quite impossible to explain
the distribution of the humus-loving and the lime-loving
species respectively by any relations of the water-content.,

The abundance of the bracken (Pteris aquilina), the gorse
(Ulex Gallii}, and the rush (Juncus effusus), which is so very
noticeable a feature of the various types of siliceous grassland,
is not seen on the calcareous grassland of this district. In fact,
on the limestone slopes below 1000 feet (305 m.), these plants
are absent or rare ; and even on the more or less leached soils

118 VEGETATION OF THE PEAK DISTRICT [CH.

above that altitude and on the limestone plateaux, all three
species are only of local occurrence. Thus the calcareous
grassland presents a different physiognomy from much of the
siliceous grassland, the former having a cleaner aspect and a
greener and more regular turf. In addition to the above
gregarious plants, many other humus-loving species are absent
or almost absent from the calcareous grassland of the slopes of
the limestone dales; and the following is a list of such species,
omitting the plants of marshy places : —

Pteris aquilina Vaccinium Myrtillus

Nephrodium montanum V. Vitis-idaea

( = N. Oreopteris) Scutellaria minor

Athyrium Filix-foemina Digitalis purpurea

Salix repens Melampyrum praten.se

S. aurita Galium saxatile

Cytisus scoparius Scabiosa Succisa

Genista anglica Jasione montana

G. tinctoria Gnaphalium sylvaticum

Ononis repens Holcus mollis

Lathyrus montanus Aira praecox

Polygala serpyllacea Deschampsia flexuosa

Empetrum nigrum Molinia caerulea

Hypericum humifusum Nardus strieta

Spergularia rubra Carex binervis

Potentilla erecta C. Goodenowii
P. procumbens var. juncella

Ulex Gallii JuncUs squarrosus

U. europaeus Luzula multiflora
Calluna vulgaris forma congesta

Erica cinerea Orchis ericetorum
E. Tetralix

On the other hand, the following plants, excluding those of
the marshy places (see Chapter VI), are found in some parts
of the calcareous grassland but are absent or quite rare in
those of siliceous grassland: —

1. In grassy places: —

Sedum acre T. fili forme

Spiraea Filipendula Hippocrepis comosa

"Potentilla verna" Hypericum hirsutum

Agrimonia Eupatoria Viola hirta (agg.)

Poterium Sanguisorba Caucus Carota

Anthyllus Vulneraria Satureia Cliuopodium

"Trifolium striatum" Origanum vulgare

IV] GRASSLAND ASSOCIATIONS 119

Verbascum Thapsus Avena pratensis

Plantago media A. pubescens

Asperula cynanchica Koeleria cristata (agg.)

Galium sylvestre "Bromus erectus"

Scabiosa Columbaria Brachypodium pinnatum

Campanula glomerata Carex omithopoda

Pulicaria dysenterica Ophrys apifera

Inula squarrosa "0. muscifera"

Senecio erucifolius Orchis morio

Picris hieracioides 0. ustulata

Leontodon hirtus 0. pyramidalis
Hieracium spp.

2. In rocky places, particularly where sheltered: —

Asplenium viride Geranium lucidum

A. Trichomones G. sanguineum

A. Adiantum-nigrum Hypericum montanum

A. Ruta-muraria Pimpinella magna

Cystopteris fragilis Satureia Acinos

Thalictrum minus Galium asperum

Draba muralis Valerianella carinata

Sedum Telephium V. olitoria

"Saxifraga sphonhemica" Centaurea Scabiosa

S. hypnoides Allium vineale

Rosa spinosissima A. oleraceum

3. In places, where the soil is loose, all semi-ruderai
plants, occurring, as a rule, most abundantly on the refuse-
heaps ("rakes") of old lead-mines or modern gravel- workings]: —

Arenaria verna Thlaspi virens

A. serpyllifolia "T. sylvestre"

Cardamine hirsuta Saxifraga tridactylites

Cochlearia alpina Alchemilla arvensis

Hutchinaea petraea Viola lutea
Arabis hirsuta var. amoena

Sisymbrium Thalianum V. calaminaria

Erophila verna Myosotis collina

var. virescens Sherardia arvensis

E. praecox Carduus nutans

"E. inflata" Cnicus eriophorus

From the above lists, it will be seen that calcareous grass-
land differs greatly from siliceous grassland not only in the
soil conditions but also in the floristic composition. In my
judgment, the edaphic characteristics of the habitats are so
essentially different that the two types of grassland, siliceous

120 VEGETATION OF THE PEAK DISTRICT [CH.

grassland and calcareous grassland, should not be placed in the
same plant formation ; and the same conclusion is indicated by
a study of their floristic composition and the related plant
associations.

Gradmann (1909: 94) has maintained that a plant forma-
tion can be defined floristically; and if this conclusion be
accepted, it would seem to be indicated that the siliceous
grassland and the calcareous pasture, although often possessing
the same physiognomy and the same plant form, must be
assigned to different plant formations.

On bushy banks, where there is some shelter from the wind
and where the soil is comparatively damp, many shrubs of the
ash woods and of calcareous scrub occur; and these shrubs, in
their turn, shelter several herbaceous species of the ash woods
and scrub. Many of such communities, in fact, appear to be
progressive associations which will finally become ash woods;
and it is impossible to draw any hard-and-fast boundary line
between woods, scrub, and grassland either of the siliceous or
the calcareous soils of this district. The transitional associa-
tions of these hill-slopes are strictly analogous with the tran-
sitional associations occurring on the wet, acidic, peaty soils of
the " Hochmoors so abundantly scattered in the foothills on the
Jura ridges, the Black Forest, and the Vosges. In contrast to
the Hochmoors of the north German plain, there occurs here,
as is well known, Pinus montana in great communities, but by
no means everywhere: even on the moors where it flourishes,
wide stretches are often quite free from it. If one now starts
with the ordinary physiognomical division [of forests, scrub,
grassland, etc.], it becomes necessary to split the natural and
sharply defined plant community of the Hochmoor into at least
three if not into four or five formations ; and these must further
be assigned to the most varied positions in the system.
According as Pinus montana forms well-developed trees, or
is the dwarfed form, or is absent altogether, the bit of the
Hochmoor in question belongs to the forest formations, or to
the scrub formations, or to the moss formation : where Ericaceae
occur socially the same Hochmoor becomes a dwarf-shrub
formation : where a turf of Carices, Eriophorum, or Scheuch-
zeria predominate, we have a ' meadow.' And yet the floristic
composition is almost exactly the same : the local conditions,

Figure 17.

Calcareous Scrub and Grassland.
Rocky hill slope of Carboniferous Limestone.

W. S. Crump

IV] GRASSLAND ASSOCIATIONS 121

the ecological relations show scarcely any perceptible alteration ;
and the soi-disant ' formations ' everywhere pass imperceptibly
one into another " (Gradmann, 1909 : 92). This criticism of a
method of classifying plant communities goes to the root of
the matter ; and the point of view which Gradmann here states
with lucidity and vigour is precisely the point of view which
the British school of plant geographers has definitely adopted.

On bare slopes, where the soil is very dry, shallow, and
calcareous, the dominant grass (Festuca ovina) tends to become
much less abundant; and small plant societies, dominated by
such species as Brachypodium gracile, Lotus corniculatus, and
Thymus Serpyllum become numerous and abundant.

The vegetation of the marshy places of the limestone slopes
is described in Chapter VI.

Mixed Calcareous Grassland

On ascending a steep slope of calcareous pasture in one of
the^ limestone dales, it is found that, at an elevation of about
1000 feet (305 m.), it opens out on to a plateau of upland
cultivation. From this plateau, rounded hill-summits rise, the
highest of which, on Bradwell moor, reaches an altitude of
1550 feet (472 m.). On the lower portions of the limestone
plateau, calcareous pasture may occur; but this is here fre-
quently fenced by characteristic white walls of loose blocks of
limestone. The walls indicate that some attempt has been
made to reclaim the land, and that regular grazing takes place.
Where the land has been ploughed at least once, and cultivation
continued, either permanent pasture or arable land still occurs
(see Chapter VIII) ; but if the land has never been ploughed or
if it has lapsed from cultivation, a type of grassland occurs
which is related to the primitive calcareous grassland. Sheep,
cattle, and horses may be frequently grazed over it ; and thus
those plants of the calcareous grassland which cannot endure
a high nitrogen content of the soil die off, while the rest remain.
A few other plants which tolerate the manuring of the soil
invade the pasture ; and thus a type of grassland occurs which
is, in a general way, related to the " Fettwiesen " of the Swiss
plant geographers (cf. Brockmann, 1907 : 332; Riibel, 1911 :
143).

122 VEGETATION OF THE PEAK DISTRICT [CH.

Analogous vegetation occurs, of course, on the grasslands
of the sandstones and shales. However, the details of British
grassland associations, or groups of associations, have not yet
been fully investigated.

On the limestone plateaux, such tracts of grassland are
frequently characterized by the great abundance of the mountain
pansy (Viola lutea and V. lutea var. amoena), which, in early
summer when the plant flowers with great exuberance, gives
rise to a distinct facies or aspect.

Transitional Calcareous Grassland

At still higher altitudes (about 1100 feet = 335 m.), a type
of pasture occurs which is transitional between calcareous
grassland and siliceous grassland. A certain number of heath-
loving or humus-loving species, such as Luzula multiflora,
Potentilla erecta, Poly gala serpyllacea, and even Ulex Gallii,
and also a certain number of lime-loving species, particularly
Poterium Sanguisorba, may occur; and, under these circum-
stances, such grassland may be regarded as transitional between
calcareous and siliceous grassland. Such grassland occurs also
on the Carboniferous Limestone in Yorkshire. Analysis shows
that the superficial soil of such localities is comparatively poor
in lime, even when the subsoil consists of limestone, and, as
stated in the introductory chapter, even when there are no
glacial or other foreign deposits. Doubtless the soil, in the
course of ages, has had much of its lime carried away in
solution. This type of grassland is, on the vegetation maps,
given the same colour as that used for siliceous grassland.

CALCAREOUS HEATH

Where the lime-content of the superficial layer of soil is
still lower, such dwarf-shrubs or under-shrubs as the heather
(Calluna vulgaris) and the bilberry ( Vaccinium Myrtillus) may
occur ; and thus transitions occur between calcareous grassland
and heath. This transitional association may be termed a
calcareous heath. The association occurs on the Carboniferous
Limestone in Somerset (Moss, 1907 a : 46), usually at altitudes
above 600 feet (183 m.), below which altitude, typical calcareous

IV] GRASSLAND ASSOCIATIONS 123

grassland is there the rule. In the west of Ireland, calcareous
heath is widespread on an extensive lowland plain of Carboni-
ferous Limestone in co. Clare (see The New Phytologist, 1908 :
259). The calcareous heaths of the present district are rather
meagrely developed ; but examples occur at the head of Monk's
dale north of Miller's dale, and at the east of Longstone Edge
north of Longstone. Other examples occur south and south-
east of Buxton. There is rather an important difference
between the limestone heaths of Somerset and those of the
Peak District : those of Somerset usually occur below 850 feet
(259 in.) and those of Derbyshire above 1000 feet (305 m.).
Correlated with this altitudinal difference, there is a consider-
able difference in the floristic composition of the two associations.
Whereas the limestone heaths of Somerset are characterized
by only some half-dozen heath-loving species (albeit these
are often very numerous as regards individuals) and a very
large number of lime-loving species, the limestone heaths of
Derbyshire are characterized by a small number of lime-loving
species (which, however, are abundant) and a large number of
humus-loving species. A Derbyshire botanist may obtain a
rough idea of a Somerset calcareous heath if he imagines his
grassy dale-slopes to possess all the numerous lime-loving
species which actually occur there, and to possess, in addition,
numerous and well-grown plants of ling or heather (Galluna
vulgaris), heath (Erica, cinerea), gorse ( Ulex spp.), and bracken
(Pteris aquilina). It is a factor of some importance also
that the calcareous heath of Somerset occurs on slopes which
are much less steep than those of the limestone dales of
the Peak District of Derbyshire.

Graebner (1901) has also stated that Calluna may occur on
calcareous soils, not incidentally but in quantity. A mixture
of calcicole and calcifuge species on calcareous soils has been
described by Ge'ze (1908 : 463 — 4), who also states that the
lime is frequently leached out of the superficial layers of s,oil.

It was suggested in the previous chapter that the greater
percentage of lime on the soil of the steep calcareous slopes is
probably due to the upper layers in such places being in process
of slow but continuous denudation; and hence the superficial
soil is constantly changing, and new and more highly calcareous
layers brought into use for the plants. On the other hand, the

124 VEGETATION OF THE PEAK DISTRICT [CH.

surface soils on the flatter plateaux are not washed away ; and
hence they receive no replenishment of new soil from the sub-
jacent rock: consequently, as leaching continues, the percentage
of lime in the less steep localities becomes more and more
reduced as time passes. If this reasoning be correct, it follows
that calcareous heaths should be more characteristic of flatter
and exposed situations than of steep hill-slopes; and this is
actually the case.

It is most interesting to note that the humus-loving plants
of the calcareous heath, such as the heather (Calluna vulgaris),
are shallow-rooted plants, and that the lime-loving species, such
as the burnet (Poterium Sanguisorba), are deep-rooted plants.
Thus the roots of the lime-loving species are able to reach the
lower layers of the soil where the lime-content remains high ;
and the roots of the humus-loving species perform their work
in the upper layers where the lime-content is low and the
humus-content high. The calcareous heath is therefore a
complementary plant community (cf. Woodhead, 1906: 345),
where species of antagonistic requirements live side by side
in virtue of their roots occupying different levels in the soil.

The leaching of lime from calcareous soils has, of course,
long been known ; and it is to be expected in districts like the
Pennines, the Mendips, and the west of Ireland, where the
rainfall is high. The importance of the process in ecological
plant geography is that by this means a soil may in time
become so changed in character as to support a totally different
group of plant associations from those which first occupied it.
By this process of leaching, it is conceivable that a particular
tract of calcareous pasture may ultimately disappear from a
given spot and be replaced by siliceous grassland or even by
heath or moor ; and similarly it is possible that an ash wood may
in time be superseded by an oak wood. Such a process is, in
its general effects, comparable with the changes which occur
in the conversion of a " Niedermoor " (" Flachmoor," in part)
or fen characterised by an alkaline peat into a "Hochmoor,"
or true moorland, characterized by an acidic peat.

A single plant formation is, within a district of uniform
climate, marked by a generally uniform type of soil. When,
by any means, the soil becomes radically changed, then a new
plant formation has also been called into being on the site of

IV] GRASSLAND ASSOCIATIONS 125

the former one. When, for example, a sheet of open water
becomes filled up with silt and peat, the aquatic formation has
succumbed and a fen or a peat moor has taken its place. There
are, then, not only intermediate associations in any single plant
formation, but also passage associations leading from one
formation to another. The limestone heath is such a passage
association. Geologists have long termed certain strata between
two geological formations transitional or passage beds ; and it
is to be expected from the nature of the case, that similar tran-
sitional tracts of vegetation should connect certain allied plant
formations. Doubtless some difference of opinion may arise
as to which of two plant formations a particular passage
association should be referred ; but such a matter is not really
one of fundamental importance.

Some of the bare or almost bare limestone rocks at altitudes
approaching 1500 feet (457 m.) also furnish an interesting
mixture of lime-loving and humus-loving plants. For example,
the following mixture of lime-loving and humus-loving species
was noted at Thirkelow rocks, south of Buxton : —

Asplenium viride Galium saxatile

Poterium Sanguisorba Deschampsia flexuosa

Sedum acre Festuca ovina

Vaccinium Myrtillus Nardus stricta

Calluna vulgaris Luzula erecta
Thymus Serpyllum (agg.)

In the case of the heather and the bilberry, it was found
that, whilst some of the roots of the plants were closely
appressed to the bare limestone rock, other roots of the same
plant were embedded in black humus formed chiefly of decaying
lichens and mosses. It is a matter for experiment whether
seedlings of these plants will germinate and arrive at maturity
if grown in a calcareous soil destitute of humus.

The following list of species are illustrative of the limestone
heaths of north Derbyshire : —

126

VEGETATION OF THE PEAK DISTRICT

[CH.

Lime-loving, on the
whole

Humus-loving, on the
whole

Ubiquitous

Arenaria verna

Pteris aquilina

Botrychium Lunaria

A. serpyllifolia

Potentilla erecta

Eanunculus bulbosus

Thlaspi alpestre

P. procumbens

Lotus corniculatus

Arabia hirsuta

Ulex Gallii

Linum catharticum

Poterium Sanguisorba

U. europaeus

Viola lutea

Anthyllus Vulneraria

Lathyrus montanus

Conopodium majus

Helianthemum Cha-

Polygala depressa

Gentiana Amarella

maecistus

Galium saxatile

Veronica officinalis

Sedum acre

Erica cinerea

Plantago lanceolata

Gentiana baltica

Calluna vulgaris

Crepis virens

Thymus Serpyllum

Vaccinium Myrtillus

Hypochaeris radicata

Plantago media

V. Vitis-idaea

Leontodon hispidus

Galium verum

Deschampsia flexuosa

Hieracium Pilosella

G. sylvestre

Nardus stricta

Anthoxanthum odora-

var. nitidulum

Juncus squarrosus

tum

Carlina vulgaris

J. effusus

Agrostis vulgaris

Carduus nutans

forma compactus

Briza media

Avena pubescens

Luzula multiflora

Festuca ovina

Koeleria cristata (agg.)

forma congesta

Carex flacca

Luzula campestris

PSEUDO-CALCAREOUS HEATHS

The true calcareous heath should not be confused with the
alternation of lime-loving and humus-loving species where this
alternation is due to the occurrence of non-calcareous detritus
or drift in a chalky or limestone district. Such a tract of
vegetation is made up of the mixture of small societies or
associations belonging to two or more plant formations, just as
the terrestrial vegetation of small islands dotted about a lake
differs from the aquatic vegetation in the lake itself. The true
calcareous heath occurs on soil where there is no drift or foreign
soil of any kind ; and the transitional nature of the vegetation
is due to a secular and gradual change in the nature of the
primitive, calcareous soil.

Again, many of the higher summits of that portion of north
Derbyshire which is indicated, on the geological maps, as
consisting of Carboniferous Limestone are capped by a layer
of non-calcareous chert ; and on this, of course, normal siliceous
grassland and moorland frequently occur.

IV]

GRASSLAND ASSOCIATIONS

127

SPECIES OF THE CALCAREOUS GRASSLAND
AND THE SILICEOUS GRASSLAND

The following is a fairly complete list of the plants inhabit-
ing the two groups of associations, calcareous grassland and
siliceous grassland of the southern Pennines: —

Calcareous
grassland

Siliceous
grassland

Lycopodium Selago

L. clavatum

Ophioglossum vulgatum

Botrychium Lunaria
Pteris aquilina

r to o
r

r to Is

Lomaria spicant

—

Cystoperis fragilis1

—

Phegopteris Robertiana2

—

Asplenium viride1

—

A. Trichomones1

—

A. Adiantum-nigrum1

—

Nephrodium montanum8

—

N. aristata

—

Salix repens3

S. aurita3

—

Quercus sessiliflora (dwarfed)

—

Betula pubescens (dwarfed)

—

Corylus Avellana

Rurnex Acetosella

o to a

R. Acetosa

r to o

Dianthus deltoides

Spergularia rubra

—

Arenaria verna

—

A. serpyllifolia

Sagina nodosa3

Stellaria Holostea

S. graminea

Trollius europaeus3

Ranunculus repena3

R. acris

R. bulbosus

Thalictrum minus

—

Cochlearia alpina

Thlaspi virens

—

"T. svlvestre"

—

Sisymbrium Thalianum

Cardamine hirsuta

—

Draba muralis1

—

D. incana1

—

Erophila verna

128

VEGETATION OF THE PEAK DISTRICT

[CH.

Calcareous
grassland

Siliceous
grassland

E. praecox

"E. inflate"

Arabis hirsute

Hutchinsea petraea

—

Sedum acre

*S. album (agg.)

S. Telephium1

—

"Saxifraga hirte"

—

S. hypnoides

—

S. granulate

S. tridactylites

—

Parnassia palustris3

Spiraea Ulmaria

S. Filipendula

—

Crateegus Oxyacantha (dwarfed)

Kubus spp.

r to o

Rosa spp.

r to o

Potentilla sterilis

r to o

"P. verna"

P. erecta

o to a

P. procumbens

—

P. reptans

r to o

P. Anserina3

Geum rivale

G. rivale x urbanum

( = G. intermedium)

—

Alchemilla arvensis

A. vulgaris4

r to o

var. minor

var. alpestris

Agrimonia Eupatoria

—

A. odorata

Poterium Sanguisorba

—

P. omcinale

Prunus spinosa

Pyrus Aucuparia (dvrarfed)

Genista tinctoria

G. anglica

Ulex Gallii

U. europaeus

Cytisus scoparius

Anthyllis Vulneraria

—

Lotus uliginosus*

L. corniculatus

r to a

Ononis repens

O. spinosa

—

Medicago lupulina

Trifolium medium

T. pratense4

"T. striatum"

T. repens4

r to o

IV]

GRASSLAND ASSOCIATIONS

129

T. dubium
T. filiforme
Hippocrepis
Vicia sepium
V. angustifolia
Lathyrus me
L. pratensis
Geranium m
G. pusillum4
G. dissectum4
G. lucidum1
G. Robertian
G. sanguineu
Oxalis Aceto;
Linum catha
Polygala vul£
"P. oxyptera"
P. serpyllacea
Empetrum nig
Ilex Aquifoliui
Hypericum puL
H. numifusum
H. montanum
H. hirsutum
H. quadrati
Helianthemi
Viola hirta
V. Riviniana
V. lutea

P. Saxifraga

Erica cinerea
E. Tetralix3
Vaccinium 3M
V. Vitis-idaea
Primula veris
Fraxinus e
Centaurior
( = Erytt
Gentiana j
G. baltica
Myosotis c
M. versicolor

Calcareous
grassland

Siliceous
grassland

—

s comosa

—

folia

aontana

r to o

molle *

r to a

—

anum

eum1

—

tosella

tiarticum

r to a

nlgaris

sra"

cea

—

nigrum

—

olium

—

pulchrum

r to o

sum

—

;um3

aum Chamaecistus

—

r to o

r, la

•ena

r to o

rnagna

—

r to o

n majus

r to o

Sphondylium

r to o

rota

—

Igaris

r to a

•ea

—

r to a

—

Myrtillus

r to a

aea

iris

xcelsior (dwarfed)

r to o

umbellatum

raea Centaurium)

^.marella

o to a

ollina

—

ans3

r to o

Scorodonia

130

VEGETATION OF THE PEAK DISTRICT

Calcareous
pasture

Siliceous
pasture

Soutellaria minor3

Nepeta hederacea

Prunella vulgaris

r to o

Stachys Betonica

r to o

Satureia Acinos

—

S. Clinopodium

—

Origanum vulgare

o to a

— /

Thymus Serpyllum (agg.)
Verbascum Thapsus

a
r

Linaria vulgaris

Veronica didyma4

V. serpyllifolia 4

V. Chamaedrys

o to a

r to o

Digitalis purpurea

—

r to o

Melampyrum pratense (agg.)

—

Euphrasia officinalis (agg.)

r to la

Bartsia Odontites3

Pedicularis sylvatica3

—

Ehinanthus Crista-Galli (agg.)

Plantago media

—

P. lanceolata

r to o

Sherardia arvensis4

—

Asperula cynanchica

—

Galium verum

G. Cruciata

—

G. saxatile

o to a

G. sylvestre1

—

var. nitidulum1

—

Lonicera Periclymenum

Valerianella carinata1

—

V. olitoria4

—

Scabiosa Succisa

S. Columbaria

—

S. arvensis

r to o

Campanula glomerata

—

C. rotundifolia

r to o

o to a

Wahlenbergia hederacea 3

—

Jasione montana

—

r to o

Solidago Virgaurea

Bellis perennis

r to o

Antennaria dioica

Gnaphalium sylvaticum

—

Pulicaria dysenterica

—

Inula squarrosa

—

Achillaea Ptarmica3

A. Millefolium

r to o

Chrysanthemum Leucanthemum

o to a

Senecio Jacobaea4

r to o

S. erucifolius

Carlina vulgaris

Carduus nutans

r to o

—

IV]

GRASSLAND ASSOCIATIONS

131

Calcareous
pasture

Siliceous
pasture

Cnicus eriophorus

C. palustris

Centaurea nigra

r to o

C. Scabiosa1

—

Picris hieracioides

—

Crepis virens

r to o

Leontodon hirtus

r to o

L. hispidus

r to o

L. autumnalis

r to o

Hypochaeris radicata

r to o

Taraxacum vulgare (agg.)

r to o

T. palustre

—

T. laevigatum

"T. corniculatum "

—

Hieracium Pilosella

r to o

"H. cymbifolium"

—

H. sylvaticum

—

"H. holophyUum"

—

H. vulgatum

r to o

H. sciaphilum

H. rigidum

r .

H. boreale

r to la

H. umbellatum

Anthoxanthum odoratum

r to o

Phleum pratense4

r to o

Agrostis alba3

A. tenuis

( = A. vulgaris)

A. canina3

—

Holcus lanatus3

H. mollis

—

Aira praecox

—

A. caryophyllea
Deschampsia flexuosa

D. caespitosa3

Trisetum flavescens

Avena pratensis

—

A. pubescens

—

Arrhenatherum elatius

Triodea decumbens

Cynosurus cristatus

Molinia caerulea

—

Koeleria cristata (agg.)

Briza media

o to a

Dactylis glomerata4

Poa annua4

P. pratensis4

Festuca ovina

a to d

r to la

F. rubra

F. elatior (agg.)

9—2

132

VEGETATION OF THE PEAK DISTRICT

[CH.

"Bromus erectus"
B. mollis4
Brachypodium sylvaticum

B. pinnatuin
Nardus stricta
Scirpus compressus3
Carex caryophyllea

C. ovalis

C. disticha3
C. flacca

C. Goodenoughii 3
C. ornithopoda1
C. pilulifera
C. binervis
C. hirta3
Juncus inflexus

(=J. glaucus)
J. effusus3
.1. squarrosus3
Luzula vernalis
L. campestris
L. multiflora

forma congesta
*Allium vineale
A. oleracexim
Ophrys apifera
"O. muscifera"
Orchis morio
0. mascula
O. maculata
0. ericetorum
0. ustulata
0. pyramidalis
Habenaria viridis
H. bifolia
H. conopsea
"H. albida"
Listera ovata
Spiranthes autumnalis

Calcareous
grassland

1
a
vr

vr
la

1
vr

r
r

la
r

r to o
a

vr
vr
vr
vr
r
la
lo

r
vr

r to o
vr

Siliceous
grassland

1
1

lo
la

o
o
r

la
r to o

o
r to o

vr
Ir

1 Chiefly on rocks. 2 Chiefly on screes.

4 Chiefly invaders from the permanent pasture.

In marshy places.

IV]

GRASSLAND ASSOCIATIONS

133

RELATIONSHIPS OF THE PLANT ASSOCIATIONS OF THE
SILICEOUS AND THE CALCAREOUS SOILS

Precisely the same line of reasoning which decides one to
place the oak and birch woods in the same plant formation as
the scrub and the grassland of the siliceous soils decides one
also to place the ash woods and the scrub and the grassland of
the calcareous soils in another single formation.

The parallel relationships of these formations and associa-
tions, as developed on the southern Pennines, may be expressed
diagrammatically in the following manner : —

Plant Formation

of the

Siliceous Soils1

Calcareous Soils1

Oak and Birch woods

Ash woods

| 8

o
02

•?

Scrub 2

Scrub

1 S

J§

Siliceous grassland

Calcareous grassland

1 Cf. Grisebach's (1846 : 73 and 156, and 1849 : 340—342) usage of the term
'plant formation," and also Schimper's (1903 : 161).

The limestone cliffs : limestone screes. Sandstone rocks and screes.
Are the plants of cliffs and screes lithophytes ?

THE LIMESTONE CLIFFS

LIMESTONE cliffs are very numerous in the district, and
some of the gorges, as the one known as the Winnats, near
Castleton, are two hundred feet (61 m.) deep. It appears to
be generally accepted among geologists that such limestone
gorges represent ancient underground water-ways whose roofs
have collapsed.

On the damper and more sheltered cliffs, ferns and flowering
plants occur in the crevices and on the ledges. Most of these
plants are members of the neighbouring plant associations, such
as ash woods, scrub, and calcareous pastures. Near villages, as
on the cliffs near Middleton at the foot of Middleton Dale,
several alien plants have established themselves. The richness
of the vegetation of the limestone cliffs varies with their
dampness, the damper cliffs being rich in species, the driest
ones extremely poor. The dampness dr dryness of the cliffs
is largely determined by the dip of the strata ; and hence, in
any gorge, the rocks on one side are usually richer in plants
than the rocks on the opposite side. For the same reason, the
vegetation of the opposite sides of a valley may vary some-
what in character. Aspect alone does not usually appear to
be a fundamental differentiating factor, except in the case of
species at or near their limit of distribution.

In the following list of the more characteristic plants

Figure 18.

Ash Wood and Limestone cliffs.
River Wye flowing between Limestone cliffs.

CH. V]

ASSOCIATIONS OF ROCKS AND SCREES

135

occurring on the limestone cliffs of Derbyshire, the species
which do not occur on the sandstones or shales are preceded
by the letter " L." The list is by no means an exhaustive one,
as a full list would contain many of the plants of the ash
woods, related scrub, and calcareous pasture. However, certain
species are more partial to the cliffs than to any other kind of
habitat. The following are species of this character : —

Liverworts.

Frullania Tamarisci
L. F. dilatata
L. Lejeunia calcarea
L. L. serpyllifolia
L. L. Rosettiana
L. Porella platyphylla
L. Scapania aequiloba

S. aspera

Pedinophyllum intermptum

Jungermannia riparia
L. J. turbinata

J. bantriensis
L. Metzgeria pubescens

M. furcata
L. Reboulia hemisphaerica

Riccia glauca

Mosses.

Ditrichum flexicaule

"Swartzia montana"
L. Selegeria Doniana
L. S. pusilla L.

L. S. acutifolia

L. "S. tristicha" L.

L. "S. calcarea" L.

Fissidens spp.

F. decipiens

F. adantioides
Grimmia apocarpa

G. pulvinata
Rhacomitrium canescens
R. lanuginosum
Tortula muralis

T. subulata

Barbula rubella

B. tophacea L.

L. Weissia calcarea

W. rupestris

Trichostomum crispulum
L. T. mutabile

T. tortuosum L.

Encalypta vulgaris

E. streptocarpa

Zygodon viridissimus
Orthotrichum anomalum
0. cupulatum
Funaria calcarea
F. hygrometrica
Bartramia Oederi
Webera cruda
Bryum spp.
B. capillare
Minum spp.
M. stellare
Neckera crispa
Anomodon viticulosus
Pleuropus sericeua
Campothecium lutescens
Eurynchium murale
E. tenellum
E. Teesdalei
E. pumilum
E. Swartzii
E. crassinervium
Amblystegium spp.
A. confervoides
Hypnum spp.
H. molluscum

136

VEGETATION OF THE PEAK DISTRICT

[CH.

Vascular plants.

L. Polypodium vulgare. Rare

L. Asplenium viride. Bare

L. A. Trichomones

L. A. Kuta-muraria

L. A. Adiantum-nigrum

L. Ceterach officiniarum. Rare

L. Phyllitis Scolopendrium. Rare

L. Cystopteris fragilis

L. Taxus baccata. Local

L. " Juniperus communis." Rare

Corylus Avellana

Urtica dioica
L. Parietaria officinalis. Local

Lychnis dioica
L. Silene nutaus. Local
L. Thalictrum minus. Local
L. *Arabis albida. Local
L. A. hirsuta
L. Cardamine impatiens
L. Hutchinsea petraea. Local
L. Draba muralis
L. D. incana. Rare

Erophila vulgaris
L. E. praecox. Local
L. Cochlearia alpina. Local

Sisymbrium Thalianum
L. *Cheiranthus Cheiri. Local
L. *Iberis amara. Local

Cardamine flexuosa
L. C. hirsuta
L. Viola hirta
L. V. sylvestris

V. Riviniana
L. var. villosa
L. Sedum acre

S. anglicum. Local
L. S. Telephium
L. "Saxifraga hirta." Rare
L. S. hypnoides
L. S. tridactylites
L. *S. umbrosa. Rare
L. Pyrus Aria. Local

P. Aucuparia. Local
L. Poterium Sanguisorba
L. Geranium lucidum

L. G. sanguineum. Local

G. Robertianum

Li nut n catharticum

Polygala vulgaris

"P. oxypteris." Rare
L. Helianthemum Chamaecis-

tus
L. Pimpinella magna

Fraxinus excelsior
L. *Lamium maculatum

Myosotis sylvatica

M. arvensis

var. umbrosa
L. Galium sylvestre
L. var. nitidulum

Valerianella olitoria
L. V. cruciata
L. *Kentranthus rubra
L. Scabiosa Columbaria
L. Centaurea Scabiosa

*Chrysanthemum Parthe-
nium

C. Leucanthemum

*Doronicum paraloides

Lactuca muralis

Taraxacum officinale

T. erythrospermum

"T. laevigatum"

Hieracium Pilosella

H. brittanicum

" H. rivale." Rare
L. " H. cymbifolium." Rare

H. sylvaticum

L. "H. rubiginosum." Rare
L. "H. holophyllum." Rare

H. vulgatum

" H. diaphanoides "

H. sciaphilum

H. rigidum

"H. prenanthoides "

H. boreale. Rare

H. umbellatum. Local

Arrhenatherum avenaceum
Brachypodium gracile

V] ASSOCIATIONS OF ROCKS AND SCREES 137

L. Melica nutans. Local L. C. ornithopoda. Local

M. uniflora C. pallescens. Local

Festuca ovina Tamus communis

Poa nemoralis. Local L. Convallaria majalis. Local

Carex pulicaris. Local

Limestone pavements, which are so characteristic of the
limestone plateau of the mid-Pennines (see Smith and Rankin,
1903 : 167) and of the lowland limestone plain of Co. Clare
(see New Phytologist, 1908 : 258) scarcely occur in the Peak
District of Derbyshire.

Ostenfeld (1908: 972), in his account of the vegetation of
the cliffs of the Faeroes, states that the water-content of the
soil, "before all others is the factor which has the greatest
influence, and is the first and most important condition in
differentiating between plant associations with the same geo-
graphical and topographical position": this remark is doubtless
true when the rocks and soils in question are of a similar
chemical composition; but such a classification of the plant
associations of a district which, like the Peak District, consists
on the one hand of sandstone rocks and siliceous soils and of
limestone rocks and highly calcareous soils on the other, would
give a very queer and a most unnatural result. Water-content
alone fails to supply a primary differentiating factor of the plant
associations in a district like this where sandstone rocks are
sharply contrasted with limestone rocks. The only primary
factor giving a natural classification of the plant associations of
the terrestrial soils of this district is one based on the presence
as contrasted with the comparative absence of lime in the soil.
Secondarily, or when applied either to the siliceous or to the
calcareous soils alone, water-content becomes a decisive eco-
logical factor; but even this is complicated by the acidic
humus-content of many of the siliceous soils.

Limestone Screes

The screes consist of angular pieces of rock, a few inqhes
in diameter on the average, which have fallen from the dis-
integrating cliffs above. Such stretches of weathered debris
are of common occurrence on the slopes of the hills in the
limestone area. The screes of this district, however, are not
specially well developed ; and in no cases are they difficult or
dangerous to traverse. The vegetation of the limestone screes

138 VEGETATION OF THE PEAK DISTRICT [CH.

of Somerset has been previously described (Moss, 1907 a : 49) ;
and, of the species of plants there mentioned, all except the
Welsh poppy (Meconopsis cambrica) occur in Derbyshire, though
in this locality the scaly fern (Ceterach officinarurn), the harts-
tongue (Scolopendrium vulgar e), the yew (Taxus baccata), and
the whitebeam (Pyrus Aria) are much rarer than in Somerset.

Here, the screes are never of great depth; and very often
plants, whose aerial parts appear above the loose talus, are
rooted in the soil below. Such soil does not differ materially
from the rest of the soil of the limestone slopes, but, being
covered by stones, evaporation is less intense. Thus, a few
moisture-loving species, such as Allium ursinum, Geranium
Robertianum, Mercurialis perennis, Scrophularia nodosa, and
Valeriana sambucifolia, apparently occur on the older screes.
Closer examination, however, proves that all these plants are
really rooted in the soil below the screes. There are, in fact,
no true " lithophytes " on the screes of Derbyshire or Somerset,
except perhaps the lichens and some of the mosses that grow
on the bare rocks and stones themselves.

The screes, however, are interesting as they furnish examples
of open associations. Doubtless, in most cases, woodland or
scrub or grassland characterized the hill-slopes which are now
covered by the screes before the latter fell away from the rocky
escarpment above. The debris would destroy the original plant
associations ; and the new surface would thus afford a suitable
habitat for the invasion of plants from the neighbouring
associations. Newly formed screes, since they have very little
vegetation, may be regarded as edaphic deserts. In fact,
probably all open plant associations, in all non-arctic or non-
alpine districts, which have a mean annual rainfall of fifteen
inches (28 cm.) or more, may be so regarded. Only those plants
which have long subaerial organs are able to colonize the newer
screes. Where the screes are continually, though perhaps
slowly, accumulating, the plant associations remain in an open
condition. On such new screes, the following plants have been
observed thinly scattered about: —

Phegopteris Robertiana Corylus Avellana (dwarfed)

( = Polypodium calcareum) Geranium Robertianum

Arrhenatherum avenaceum Teucrium Scorodonia

Brachypodium gracile Fraxinus excelsior

V] ASSOCIATIONS OF ROCKS AND SCREES 139

On the older screes, the plant associations tend to become
more and more closed; and it is well known (cf. Warming,
1909 : 246) that screes often show a developmental history. In
this district, as in Somerset, three types of plant succession
may be recognised as characteristic of the screes. The most
frequent case is the succession which terminates in calcareous
grassland. A not uncommon succession terminates in an ash
wood, and intermediate stages of this succession are well shown
on screes in Haydale, east of Cressbrook Dale. The least
frequent succession leads on to a kind of limestone heath,
as at the head of Monksdale, north of Miller's dale, where
Calluna vulgaris occurs side by side with lime-loving plants:
Smith and Rankin (1903 : 167) mentioned that a similar kind
of vegetation is seen on some of the limestone screes of the
mid-Pennines.

The following list was compiled from older screes adjoining
an ash wood: —

Phegopteris Robertiana Scrophularia nodosa

Cystopteris fragilis Teucrium Scorodonia

Polypodium vulgare Galium sylvestre

Corylus Avellana Sambucus nigra

Urtica dioica Campanula rotundifolia

Thalictrum minus Valeriana sambucifolia

Sedum acre Valerianella olitoria

Saxifraga hypnoides V. carinata

Rubus saxatilis Senecio Jacobaea

Crataegus Oxyacantha Solidago Virgaurea

Geranium lucidum Picris hieracioides

G. sanguineum Arrhenatherum avenaceum

G. Robertianum Brachypodium sylvaticum

Oxalis Acetosella Melica nutans

Mercurialis perennis Convallaria majalis

Cornus sanguinea Allium ursinum

On higher mountains than occur in Derbyshire, screes are
developed to a correspondingly great extent : and the stones
composing the screes may then be many yards in diameter.
The vegetation of such block-screes is usually extremely scanty,
as the large size of the boulders prevents so much light from
reaching the soil below that seedling plants are unable to
reach maturity. Such tracts are well known in the Alps, and
have been described by the Swiss plant geographers under

140 VEGETATION OF THE PEAK DISTRICT [CH.

the name qf Gerollflur or Gerollflora or Schuttflora (cf. Ottli,
1905: 18). Brockmann (1907 : 290 — 1) subdivides his " forma-
tions group " of the Gerollflora into plant communities (a) on
siliceous rocks, and (6) on calcareous rocks, and gives lists of
plants for each subdivision. It may well be that in districts
like the Alps, where the great differences in altitude produce
very marked differences in the vegetation at different heights,
the vegetation of the Alpine boulder-strewn ground belongs
to a different plant formation from other parts of the mountain
slope; but in this district, where the differences in altitude
on the limestone hill-slopes are comparatively slight, and
where the depth of the debris of stones is rather insignificant,
the plant communities seen on the screes can scarcely be
separated from those on the other parts of the hill sides (cf.
figure 21).

SANDSTONE ROCKS AND SCREES

Screes and boulder-strewn slopes also occur to some extent
on the siliceous slopes below escarpments of the Carboniferous
gritstones ; but here also the flora partakes of the same general
composition as that of the associations in close propinquity.
For example, the sandstone screes in the moorland area are
characterized by such plants as Calluna vulgaris, Vaccinium
Myrtillus, V. Vitis-idaea, Arctostaphylos Uva-ursi, and Des-
champsia flexuosa, which are rooted not on the bare sandstone
rocks but in the soil in which the boulders are embedded,
or in the clefts of the rocks, or on soil which has accumulated
on the projecting ledges.

Most of the sandstone rocks and screes of the district occur
in the moorland area. Occasionally they occur in woods, and
only rarely in the grassland or cultivated areas. As in the
case of the limestone rocks and screes, the plants present
belong for the most part to the adjoining associations. For
example, on the numerous " edges " or sandstone escarpments
of the moorland area, humus collects in the rocky crevices,
and on the rocky ledges; and here moorland plants prevail
(see figure 19), particularly the bilberry (Vaccinium Myrtillus).
The same remark applies to the sandstone screes of the moor-
land area, though, as these receive a considerable amount of

Copi/riylit

Figure 19.

Rocks of Millstone Grit.

Bilberry (Vacciniuin Myrtillus) on the ledges; and a rock-moss
(Andrcaea liothii) on the face of the cliff at the extreme left.

ASSOCIATIONS OF ROCKS AND SCREES

141

shelter from the cliffs above them, they have a rather richer
flora (see Chapter VII).

Although a fairly long list of cellular flowerless plants,
which occur on the faces of the sandstone rocks, is given below,
most of the species are very rare and local ; and it is scarcely
possible to single out any vascular plants which, in this district,
exhibit any pronounced partiality for living on the sandstone
rocks. Many of the cellular cryptogams are very susceptible
to the action of smoke (Wilson, 1900); and, as the southern
Pennines are situated between two great manufacturing districts,
it is highly probable that many of the mosses and lichens char-
acteristic of bare rocks are even rarer now than they were a
century ago. The following silicolous and saxicolous cellular
plants have been recorded (Linton, 1903; Crossland, 1904; etc.)
for the sandstone rocks of the southern Pennines : the species
which are confined to such rocks are preceded by the letter

S. Andreaea Rothii

S. A. crassinerva

S. A. alpina

S. A. petrophylla

S. Tetraphis Browniana

S. Swartzia moutana

S. Dicranum fuscescens

Grimmia apocarpa

G. pulvinata

G. trichophylla

G. Doniana
S. Rhacomitrium fasciculare

S. R. heterostichum

R. lanuginosum

R. canescens

Phytomitrium polyphyllum
S. Campylosteleum saxicola
S. Hedwigia ciliata

Tortula muralis

Eurhynchium murale

Leconora, ? sp.

Lecidea, '( sp.
8. Parmelia saxatilis
S. Pertusaria dealbata

Crampton has recently described the vegetation of the
screes of Caithness. The plants of these screes are chiefly
humus-loving species, such as frequently occur on the sandstone
screes of the Pennines; and there would appear to be little
justification for giving the vegetation in question the rank
either of " formation " or even " subformation " (Crampton,
1911 : 26 and 43). This will perhaps best be seen by quoting
all the species mentioned by Crampton. Those which do not
occur on the Pennines are indicated by a f : —

Sphagnum spp.
Rhacomitrium lanuginosum
Hylocomium spp.

Hypnum Schreberi
tSilene amoena
tAlchemilla alpina

142 VEGETATION OF THE PEAK DISTRICT [C'H.

Rubus Chamaemorus Melampyrum pratense

Empetrum nigrum Galium saxatile

Erica cinerea Anthoxanthum odoratum

Calluna vulgaris Agrostis tenuis

tAzalea procumbens Deschampsia flexuosa

Vaccinium uliginosum Festuca ovina

V. Myrtillus Luzula sylvatica

V. Vitis-idaea L. campestris

ARE THE PLANTS OF THE CLIFFS AND SCREES LITHOPHYTES ?

The precipitous faces of the cliffs are tenanted by many
species of Algae, lichens, liverworts, and mosses ; and some of
these may be regarded as " lithophytes." Many of the plants,
however, even the lower cryptogams, are not rooted on the bare
rock itself, but in the loose soil which accumulates, to a slight
extent, on the surface of the slight irregularities of the face of
the rock, even when this is nearly vertical.

Warming (1909 : 238 and 240) uses the term " lithophytes "
in a double sense. Section VIII of Warming's treatise is
headed " lithophytes" ; and these are subdivided into (1)" litho-
phytes " and (2) " chasmophytes." Warming states that this
subdivision is in accordance with the suggestion made by
Schimper (1903 — 4: 178) who wrote: — "The vegetation on
the surface of rocks or stones may be termed that of lithophytes.
Crevices in rocks, in which more finely grained components
and more water accumulate than on the surface, produce a
somewhat more copious vegetation, that of chasmophytes"
Warming (1909 : 240) also cites Ottli who defines as rock-
plants or petrophytes "all those plants, growing on sides of
rocks or blocks of detached stone, which are able, as the first
of their kind, to colonize the rock permanently, and which
display in distribution or structure a more or less pronounced
dependence upon rock as a substratum. Within this definition
are included both lithophytes and chasmophytes." Ottli (loc.
cit.) maintains that " it is not a natural scheme to co-ordinate
both lithophytes and chasmophytes; and he suggests the
following scheme : —

V] ASSOCIATIONS OF ROCKS AND SCREES 143

PETROPHYTES

(Rock plants generally-)

LITHOPHYTES CHOMOPHYTES

(Plants growing
on the bare surface | ' 1

of rocks) EXOCHOMOPHYTES CHASMOCHOMOPHYTE8

(Plants growing on ( = Chasmophytes)

the accumulated (Plants growing in

detritus of rocks) the crevices of rocks)

Of lithophytes (using the term in the strict sense) there
are probably only certain Algae, lichens, liverworts, and mosses,
i.e., plants which are able to absorb atmospheric moisture by
means of their general superficial tissues. It is doubtful if
those plants on rocks, even including Algae and lichens, which
absorb moisture by means of roots or root-like structures,
should be placed in a single plant formation. At all events, no
such "formation" is recognized in the present book, although
a subdivision of rock plants, like that of Ottli's, is very useful
from many points of view. As regards this district, it seems
sufficient to regard the vegetation of the limestone rocks and
screes as belonging to the plant formation of calcareous soils,
and the vegetation of the sandstone rocks and screes as be-
longing to the plant formation of siliceous soils except where
the plants occur on the acidic humus of the rock ledges (see
figure 19), when the vegetation would appear to be best placed
in the moorland formation.

CHAPTER VI

MARSH AND AQUATIC ASSOCIATIONS

GENERAL DISTRIBUTION OF THE MARSH (OR SWAMP)
AND AQUATIC ASSOCIATIONS

IN the Peak District, as on the Pennines generally, aquatic
and marsh associations, and more especially the former, are
very meagrely represented. The Pennines, consisting of
fissured rocks like the Carboniferous sandstones, and porous
rocks like the Carboniferous limestone, have no natural lake-
lets or tarns such as occur on the older Silurian and Cambrian
rocks. Again, in the Peak District^ there are no extensive
alluvial flats; and it is in such situations that aquatic and
marsh associations attain a maximum degree of development.
From such lowland alluvial deposits, some of the more cosmo-
politan aquatic and marsh plants spread up the streams, where
they form narrow, fringing associations which are too small,
however, to be marked on vegetation maps except such as are
constructed on a very large scale. Hence aquatic associations
and reed swamps are poorly developed and only of local
occurrence on the Pennines.

In this district, marshes or swamps are characteristic of
those spots on the hill-slopes where springs issue, and of the
immediate banks of the streams where these banks happen to
be flat. Reed swamps are very local; and even when they
do occur, they are very small and not very typical. The streams
themselves are tenanted by numerous characteristic mosses,

CH. VI] MARSH AND AQUATIC ASSOCIATIONS 145

liverworts, and Algae, but by few characteristic aquatic flowering
plants.

In a sense, some of the moorland associations described
in the next chapter are aquatic, and were so classified by
Warming (1895) in his earlier work on plant communities.
The cotton-grass moor (see page 183), for example, possesses a
soil which, during very considerable periods of most years,
is supersaturated with moisture; and many members of
the cotton-grass association possess such aquatic structural
adaptations as aeration channels in their stems and leaves. It
is now, however, very generally held (see Schimper, 1903 — 4;
and Warming, 1909) that it is the physiological and not the
physical wetness of the soil that determines whether or not
plants are really hydrophilous; and, as peaty soils are now
frequently regarded as being physiologically dry, moorland
plants are not now usually placed among hydrophytes. On
the other hand, Clements (1907 : 170) maintains that the
aquatic adaptations found in many moorland species are normal,
that the xerophytic adaptations which they possess were
acquired during some past period when the plants in question
inhabited dry habitats, and that the xerophytic structures have
persisted. It is indeed necessary to remember that very little
experimental investigation has yet been performed on the
physiological water-contents of soils, most ecologists and plant
geographers being apparently content with general impressions
and general statements.

As Schimper has pointed out (1904 : 781), " every classifica-
tion of the aquatic flora commences with the separation of
salt-water forms from fresh-water forms." All the aquatic
plants of this district belong to the latter class; and a
classification of fresh-water aquatics may be based on the
richness or poverty of the water in soluble mineral salts.
From this point of view, the aquatic species of the calcareous
streams of the district may be placed in one association, and
those of the non-calcareous streams in another.

The rivers of lowland districts are probably always rich or
fairly rich in soluble mineral salts, as the streams have in their
earlier courses dissolved much material from the rocks through
which they have cut their way; but this statement does not
apply to the small streams of non-calcareous hill-slopes. In

M. 10

146

VEGETATION OF THE PEAK DISTRICT

[CH.

the Peak District, it is easy to distinguish the vegetation of
the streams which flow over the non-calcareous or siliceous
soils and which have a very low mineral content from that of
the streams which flow over the calcareous soils and which
have a high mineral content.

NON-CALCAREOUS WATERS

The late Mr Ackroyd (1899 : 120), formerly the Borough
Analyst of Halifax, has published figures giving the composition
of the waters of a reservoir supplying that town ; and this
analysis is useful as it is typical of the whole of the non-
calcareous waters of the sandstones and shales of the Pennines,
including the Peak District. " The matters dissolved consist
of mere traces of inorganic bodies, and a small amount of

peaty acid These waters are very soft, ranging from two to

three Clark's degrees1; and the hardness is of a permanent
character2, i.e., it is not appreciably lessened on boiling." The
following is Mr Ackroyd's full analysis : —

Grains per

Grams 3 per

gallon

litre

Total solids in solution

5-25

0-075

Total solids in suspension

nil

Chlorine, calculated as NaCl

1-3

0-019

Iron, calculated as Fe203

0-03

0-004

Sulphate of lime (CaS04)

3-90

0-006

Free and albuminoid ammonia (NH3)

nil

Acidity, calculated to its equivalent of

sulphuric acid (H2S04)

0-16

Hardness = 3 degrees (Clark's) 1

SWAMPS (OR MARSHES) ON THE SANDSTONES AND SHALES

The larger streams of the district have their sources on
the peat moors, the smaller ones on the hill slopes. In the
former case, the sources of the streams occur either in the

1 A Clark's degree is one grain of carbonate of lime (CaC03) per gallon, or
its equivalent of other lime (calcium) compound.

2 Permanent hardness of water is due to sulphate of lime (CaS04), tem-
porary hardness to carbonate of lime (CaC03).

3 15-43 grains = 1 gram; 0-22 gallons = 1 litre.

Figure 20.

A Dripping Slialy Bank.

Lady Fern (Athyriuiii Filix-foemina), Foxglove (Digitalis
purpurea], Wall-lettuce (Lactuca muralix), Golden Saxi-
frage (Chrysosplenium oppositifolium), mosses, Hepatics,
Algae, etc.

VI] MARSH AND AQUATIC ASSOCIATIONS 147

heather association or in the cotton-grass association : in the
latter case, they occur in associations either of siliceous grass-
land, scrub, oak or birch wood. In all cases, however, the
source is marked by a swamp ; and these swamps are frequently,
but by no means invariably, dominated by the common rush
(Juncus effusus).

As might be inferred from the diverse surroundings of
these springs, there is a certain amount of diversity in their
flora. This difference, however, is less than might have been
anticipated, as the springs are all characterized by some trickle
of water implying a fair degree of aeration, and all are character-
ized by a low mineral-content, as is sufficiently indicated in the
analyses just given.

The poorest flora is found in the swamps surrounding the
springs which occur on the peat moors. It is sometimes stated
that the larger rushes do not occur on peat ; but Pethybridge
and Praeger (1905 : 171) find an association Juncus effusus on
peaty soils, and this is also the case on the Pennines ; so that
the statement is too sweeping. It is true that Juncus effusus
is not a normal member of any of the plant associations on
peat with stagnant water ; but whenever water from a spring
oozes through the peaty soil, there a community of the common
rush frequently occurs. The springs change their positions
from time to time, as may be seen by comparing the present
springs with those marked on the old " six-inch " Ordnance
maps. Probably when the peat was being originally formed,
the land round the then springs would be destitute of peat;
but when a spring at some later time issued from a different
place, two local changes in the vegetation would be called into
being. First, the swamp plants of the original spring would,
after a time, die ; and their places would be filled by plants
from the neighbouring moorland association, and peat would
thus form on the site of the old spring; and secondly the
aerated waters of the new spring trickling through the peat
at a different place would result in the death of many of the
moorland species of that place, and in the invasion of some
swamp-inhabiting species.

On the non-peaty slopes and at lower altitudes, the swamps
are more numerous and much richer in species. However, the
characteristic feature of all of them, whether on peat or not, is

10—2

148 VEGETATION OF THE PEAK DISTRICT [CH.

that there is some flow or trickle of water, i.e., the water is well
aerated. The swamp association of siliceous soils is typically
dominated by the common rush (Juncus effusus), yet it is a
different plant community from the Juncus facies of the sili-
ceous grassland previously described (see page 108). In this
district, the swamps of Juncus effusus are not of sufficient size
to be given a special colour on the maps, although Pethybridge
and Praeger (1905) were able to do this on their vegetation
map of the district lying south of Dublin.

The term " Juncetum " has been used by several writers to
denote a plant association whose chief constituent is a species
of the genus Juncus. Such terms were first used by the Danish
plant geographer Schouw (1822); but the term "Juncetum" is
vague, as it does not indicate the species of Juncus which is the
dominant plant. In this district, for example, there are several
kinds of "Junceta." The associations at the stream sources
have usually Juncus effusus as the chief constituent plant;
but, besides this, associations or societies occur of J. sylvaticus
(= J. acutiflorus), of J. lamprocarpus, of J. supinus, and of
/. squarrosus on the sandstones, shales, or peat ; of J. glaucus
on the limestones chiefly; and of J. bufonius on almost any soil.
In certain lowland localities, associations of J. subnodulosus
(= J. obtusiflorus) occur, and, in maritime localities, of J. mari-
timus, locally of J. acutus, and of J. Gerardi. Thus the term
" Juncetum " is very vague and ambiguous. To overcome the
ambiguity, Cajander (1903) has adopted a modification of
Schouw's plan. Cajander would add the specific name as a
genitive to the term "Juncetum": thus, an association of
Juncus effusus would be denoted by the term "Juncetum effusi1."
This plan is capable of universal application with regard to
pure associations; and hence is of great merit. Of course,
such universal terms will not supersede the common or ver-
nacular names of plant associations, just as Bellis perennis is
still known as the daisy and just as trichlormethane is still
known as chloroform. However, many associations are destitute
of common names ; and, in any case, the technical names possess
all the advantages of the binomial names in general use among
botanists and zoologists, and of the technical names in use
among organic chemists (cf. Moss, 1910 6).

1 An abbreviation of Juncetum Junci-effusi.

VI]

MARSH AND AQUATIC ASSOCIATIONS

149

At altitudes from 1000 feet (305 m.) downwards many of
the Juncus swamps are rich in species : above that altitude,
the swamps become floristically poorer and poorer.

The full list of plants of the Juncus swamps is a very long
one, in which respect the association resembles most other
mixed or unstable or kinetic associations. In the following
list the plants more characteristic of peaty localities are printed
in italics : —

Equisetum limosum

Epilobium obscurum

E. palustre

o to a

E. sylvaticum

Hydrocotyle vulgaris

Nephrodium montanum

r to o

Oenanthe crocata

Athyrium Filix-foemina

r to o

Angelica sylvestris

var. convexum

Vaccinium Oxycoccus

Salix aurita

Lysimachia nemorum

r to o

x cinerea

L. Nummularia

S. cinerea

L. vulgaris

var. aquatica

Menyanthes trifoliata

var. oleifolia

Scutellaria minor

S. repens

Ajuga reptans

Betula pubescens

Myosotis repens

o to a

Rumex Acetosa

M. caespitosa

Montia fontana forma rivu-

M. palustris

laris

var. strigulosa

M. fontana var. minor

" Scrophularia alata "

Lychnis Flos-cuculi

( = S. umbrosa)

Stellaria graminea

r to o

S. cinerea

S. uliginosa

o to a

var. aquatica

Ranunculus repens

Scrophularia nodosa

r to o

R. Flammula

o to a

Veronica scutellata

forma tenuifoliws

V. Beccabunga

R. hederaceus

" Pedicularis palustris "

R. Lenormandi

P. sylvatica

r to o

Trollius europaeus

Pinguicula vulgaris

Cardamine amara

Galium Witheringii

C. pratensis

Valeriana dioica

C. flexuosa

r to o

V. sambucifolia

Drosera rotundifolia

Scabiosa Succisa

Chrysosplenium alternif.

Wahlenbergia hederacea

C. oppositifolium

Achillaea Ptarmica

Spiraea Ulmaria

Senecio aquaticus

o to a

Geum rivale

r to la

Cnicus palustris

x urbanum

Crepis paludosa

( = G. intermedium)

Taraxacum palustre

Potentilla palustris

Lotus ulginosus

Potamogeton polygonifolius

Empetrum nigrum

Triglochin palustre

Hypericum humifusum

r to o

Agrostis alba

H. quadrangulum

o to a

A. canina var. mutica

Viola palustris

Deschampsia caespitosa

150

VEGETATION OF THE PEAK DISTRICT

[CH.

Holcus lanatus

Molinia caerulea

Qlyceria fluitans

Scirpus setaceus

Eriophorum angustifolium

Carex ovalis

C. echinata

C. paniculata

C. Goodeno^lffh^^

C. flacca

C. pallescens

C. panicea

C. pendula

"C. strigosa"

C. helodes

( = C. laevigata)
C. binervis
C. fulva
C. flava

forma oedocarpa

( = C. flava var. minor)

C. ampullacea
Juncus effusus

forma compactus
J. inflexus

( = J. glaucus)
J. sylvaticus

( = J. acutiflorus)
J. lamprocarpus
J. supinus
J. squarrosus
Luzula multiflora

forma congesta
Narthedum Ossifragum
Iris Pseudacorus
Orchis latifolia
O. maculata
0. ericetorum

vr
Is

a
la
I

la
o
I
Ir

CALCAREOUS WATERS

The composition of the calcareous waters may be inferred
from the following analyses of the waters of the Carboniferous
Limestone area of the mid-Pennines published by Mr Burrell
(1900). It will be seen that the iron-content is practically the
same as that of the non-calcareous waters, but that the lime-
content is considerably higher. The magnesium-content is also
high ; and this fact has possibly some significance. It seems to
be the case generally, although perhaps not so universally, that
natural waters with a high lime-content have also a high general
mineral-content, and conversely that waters with a low lime-
content have also a low general mineral-content ; and it is by
no means improbable that the so-called lime-loving species are
plants which prefer, not merely the lime, but the high mineral-
content in general. However, in the absence of experimental
work bearing specially on this point, no positive statements can
be made; though Graebner (1909) bases a classification of the
vegetation of Germany on an assumption, by no means an
unreasonable one, which is nearly the same as this one.

VI]

MARSH AND AQUATIC ASSOCIATIONS

151

TABLE I. CONSTITUENTS

Si02
S03
HN03
HNO,

Aire Head Spring

Smelt Hill Water Sink

Grains per
gallon

Millegrams1
per litre

Grains per
gallon

Millegrams1
per litre

0-224
1-050

o-ioo

5-2
38-6
3-4

0-139
2-049

5-1
75-5

Minute

"2^5

traces

—

traces

0-700

25-8

0-700

25-8

Fe-jOs

0-030

1-1

0-009

3-3

CaO

6-258

230-5

6-839

251-8

MgO

0-403
0-456

14-8
16-8

0-841
0-456

31-0
16-8

NH3
Albuminoid

0-007

2-6

0-003

1-1

NH3

0-006

2-4

0-018

6-6

TABLE II. DISSOLVED SALINE CONSTITUENTS

Aire Head Spring

Smelt Hill Water Sink

Grains per
gallon

Millegrams1
per litre

Grains per
gallon

Millegrams 1
per litre

0-224

8-2

0-139

5-1

Ca (N03"i2

0-130

4-8

—

CaC03

9-778
1-785

360-1
65-6

9-646
3-483

355-2

128-3

MAgCC)3
NaCl

0-843
1-155

30-9
42-5

1-759
1-155

64-7
42-5/

FeCO3

0-043
13-958

15-85
513-9

0-013
16-195

4.4
550-6

Dissolved

matter by
evaporation

14-280

525-8

16-940

576-0

1 15-43 grains = 1 gram ; 1-76 gallons = 1 litre.

152

VEGETATION OF THE PEAK DISTRICT

[CH.

Swamps are much less numerous in the limestone tract
than on the less porous sandstones and shales. Most of the
swamps in the limestone area occur at the bottoms of the
dales, although a few occur on the grassy slopes, wherever
springs issue through the soil. A very large number of species
which characterize the swamps of the sandstone and shale are
absent from those of the limestone, whilst some species are
restricted to the limestone swamps. The following species
have been found in the limestone swamps of north Derbyshire ;
and it will be seen that the total floristic composition of the
limestone swamps is very different from that of the sandstone
swamps, just as the soluble mineral content of each is very
different. These differences are sufficiently important to justify
the placing of the two kinds of swamps in separate plant
formations.

Thalictrum flavum

V. dioica

Trollius europaeus

Eupatorium cannabinum

Caltha palustris

Petasites ovatus

Chrysospleniurn oppositi-

Cnicus heterophyllus

folium

C. palustris

C. alternifolium

Festuca elatior

Parnassia palustris

F. arundinacea

Spiraea Ulmaria

Scirpus compressus

Potentilla erecta

(Blymus compressus)

Geum rivale

Carex disticha

G. rivale x urbanum

C. acuta

( = G. intermedium)

C. flacca

Epilobium hirsutum

C. pendula

Polemonium caeruleum

C. strigosa

Myosotis palustris

C. sylvatica

Mentha spp.

Juncus giaucus

"M. rotundifolia"

J. compressus

Pedicularis palustris

Helleborine palustris

Valeriana officinalis

Orchis maculata

o to a

( = V. Mikanii)

In similar limestone swamps of the mid-Pennines, the bird's
eye primrose (Primula farinosa) is abundant, and there reaches
its southern British limit.

Admitting that the two kinds of swamps should be placed
in separate plant formations, the question arises as to which

Figure 21.

B. Crump

A larger Limestone Dale.

Calcareous grassland and screes on the hill slope on the left. Ash

(Fraxinus excelsior) and Wych Elm (Ulmux glabra=U. montana)

by the stream side. In the foreground the River Wye.

Vl] MARSH AND AQUATIC ASSOCIATIONS 153

plant formations the two swamps respectively must be referred
to. They can scarcely be placed in the aquatic formation, as
they do not occur in water nor do many of the species exhibit
marked hydrophytic characters. The plants of the swamps
under discussion are not the " helophytes " of Warming (1909 :
185), the latter being members of reed swamps, which are here
included in the aquatic plant formation (see page 154). The
plants of the siliceous and calcareous swamps here alluded to
are obviously more terrestrial in character than the members
of reed swamps, and should probably be placed in the two main
formations of the district which, like the swamps in question,
occur on the siliceous and calcareous soils respectively. On
this basis, the swamps of the sandstones and shales would be
placed in the same formation as the oak woods, scrub, and
siliceous grassland ; whilst the swamps of the limestone area
would be placed in the same formation as the ash woods, scrub,
and calcareous grassland. This arrangement conforms with the
general edaphic conditions, the general floristic composition,
and the topographical position of the two kinds of swamps in
question (cf. the summary on p. 215). These swamps and their
related vegetation are obviously allied to the "Formation der
Quellfluren" of the Swiss plant geographers (cf. Riibel, 1911 :
193).

RUDERAL MARSH SPECIES

In addition to the species which are definitely members of
the swamps in the vicinity of springs, there are a number of
other marsh plants of the district which cannot be referred to
either of the preceding plant associations, and which in their
distribution remind one of the ruderal plants inhabiting dry
"waste places" and roadsides. Many of the marsh ruderal
plants are found in wet places on stream-banks liable to be
flooded in times of heavy rains ; but they also occur in any
kind of wet places to which their reproductive parts may
happen to get carried. They are usually found in the more
lowland localities, and they are more at home in the marsh
associations of the alluvial plains. The names of a number
of such plants are given on the next page ; but, in addition to
the following, several plants of the swamps also exhibit ruderal
or viatical tendencies : —

154

VEGETATION OF THE PEAK DISTRICT

[CH.

Rumex conglomeratus

Mentha spp.

Polygonum Hydropiper

*Mimulus Langsdorfii

Ranunculus repens

Veronica Beccabunga

o to a

Nasturtium palustre

Gnaphalium uliginosum

N. officinale

Petasites ovatus

Barbarea vulgaris

Pulicaria dysenterica

Potentilla Anserina

Alopecurus geniculatus

Apium nodiflorum

Carex hirta

Slum erectum

Juncus bufonius

Scutellaria galericulata

REED SWAMPS

There being no extensive, shallow, sheets of water in the
district, it follows that reed swamps are not common and are
not typically developed. The most characteristic member
(Phragmites communis) of reed-swamps in general has only,
in the course of the present botanical survey, been observed in
lower Monsal Dale, where, in the back waters of the river Wye,
it forms one or two small associations or societies. However,
most of the streams of this hilly district have a fairly strong
current ; and this factor of itself is sufficient to account for the
paucity of reed swamps of Phragmites communis by the stream
sides. It appears to be generally the case that this plant
only forms typical reed swamps in stagnant or almost stagnant
waters ; and, where the water is well aerated, any reed swamps
that occur are dominated by other plants, such as Olyceiia
aquatica and Phalaris arundinacea. In this district the two
latter plants are frequently dominant in plant societies or
small associations up to about 600 feet (183 m.). The latter
plant, however, occasionally occurs up to about 900 feet (274 m.).

The following plants occur in the small and rather non-
typical reed swamps of the southern Pennines : it will be seen
that many of the species are in this district only of local
occurrence : —

VI]

MARSH AND AQUATIC ASSOCIATIONS

155

In non-

calcareous

waters

Equisetum maximum

E. palustre

E. limosum

Polygonum amphibium

*Nasturtium amphibium

—

N. palustre

"Lythrum Salicaria"

Epilobium hirsutum

Angelica sylvestris

*Lysimachia vulgaris

—

Stachys palustris

Veronica Anagallis

—

Eupatorium Cannabinum

*Bidens tripartita

—

*Typha latifolia

Sparganium ramosum

r to o

*S. simplex

Triglochin palustre

Alisma Plantago

*Sagittaria sagittifolia

Phalaris arundinacea

Agrostis alba

r to o

Phragmites communis

Glyceria aquatica

Eleocharis palustris

—

Carex remota

C. inflata

( = C. ampullacea)

C. acutiformis

( = C. paludosa)

C. vesicaria

*Acorus Calamus

—

Juncus effusus

J. inflexus

( = J. glaucus)

—

Iris Pseudacorus

—

THE VEGETATION OF QUICKLY FLOWING STREAMS

("The hydrophyte formation round springs and streamlets."

Ostenfeld, 1908 : 943.)

The streams of the Pennine slopes are characterized by their
quick current and their shallowness. A result of their quick
current is that the water is well aerated; and this factor is

156 VEGETATION OF THE PEAK DISTRICT [CH.

related to the absence of a large number of lowland aquatic
flowering plants. The shallowness of the streams assists
towards the same result. The streams on the sandstones and
shales are deficient in humous acids, except in the case of the
streams which drain the peaty deposits of the plateaux. The
streams of the limestones are not merely deficient in humous
acids, but are actually alkaline in reaction.

On the flatter moorland plateaux in streams draining from
the peat moors, a pond weed (Potamogeton polygonifolius) is
indigenous. This plant appears to be confined to acidic waters.
A crowfoot (Ranunculus Lenormandi) is locally abundant in
similar situations, as well as in small streams and swamps on
the hill-slopes of the sandstones and shales. JR. hederaceus is
very much rarer. Glyceria fluitans and Callitriche stagnalis
are found in the streams, in reservoirs and mill dams, and in
swamps up to 1500 feet (457 m.). Montia fontana, M. minor,
and Stellaria uliginosa are also locally very abundant in the
streams on the sandstones and shales. The Batrachian crow-
foots are almost confined to the limestone streams, where,
however, they are locally very abundant, especially so below
500 feet (152 m.). Species of Chara are also limited to the
calcareous streams, whilst Nitella opaca occurs rarely in both
the calcareous and the non -calcareous waters of the district.

Ostenfeld (loc. tit.) includes "the vegetation on cliffs over
which water constantly trickles " with the vegetation of round
springs and streamlets, and this appears quite a reasonable plan;
and Ostenfeld (loc. cit.) is also quite reasonable in refusing to
follow Jonsson in placing this type of vegetation with the moss-
bogs described by Warming, which are characterized by stagnant
and not by well aerated water.

On the whole, however, flowering plants are not generally
abundant in quickly flowing streams; but this deficiency is
more than compensated by the great abundance and variety
of liverworts and mosses. Bog-mosses (Sphagnum spp.) never
occur in the streams of the limestone hill-slopes, and are not
common in those of the siliceous hill-slopes except when these
are rich in humous acids. Algae are locally abundant and
equally characteristic, but have not been studied ecologically.

The following liverworts and mosses have been observed in
the streams of the southern Pennines :

VI]

MARSH AND AQUATIC ASSOCIATIONS

157

In non-

calcareous

waters

Hepaticae

Jubula Hutchinseae

—

Scapania undulata

—

S. purpurascens

—

"S. intermedia"

—

Chiloscyphus polyanthus

Jungermannia incisa

—

J. cordifolia

—

Nardia hyalina

—

N. obovata

—

r to o

N. compressa

—

"Pellia Neesiana"

—

Aneura multifida

A. pinguis

"A. ambrosioides"

—

Musci

Sphagnum crassidulum

—

Dicranella Schreberi

D. squarroea

—

Fissidens crassipes

—

Rhacomitrium aciculare

—

Cinclidotus fontinaloides

—

Orthotrichum rivulare

—

Aucolocomnium palustre

—

Philonotis fontana

—

"P. adpressa"

—

P. calcarea

Webera albicans

" Bryum filiforme "

—

Fontinalis squamosa

F. antipyretica

r to o

" Porotrichum angustifolium "

—

" Leskea polycarpa "

Brachythecium rivulare

B. plumosum

Hyocomium flagellare

—

o to a

Eurynchium rusciforme
Amblystegium irriguum

a
r

A. fluviatile

—

Hypnum riparium

H. uncinatum

H. fluitans (agg.)

—

H. commutatum

H. falcatum

H. palustre

H. ochraceum

H. stramineum

—

158 VEGETATION OF THE PEAK DISTRICT [CH.

ALIEN AQUATIC PLANTS

A large proportion of the aquatic species occur in the canals
and mill-dams, and were not recorded by the older botanists
who flourished before these habitats were constructed. Hence
it is unlikely that such plants existed as members of the
primitive flora of a district which originally was almost if not
quite destitute of natural sheets of still waters. However, on
the construction of the canals and mill-dams about a century
ago, aquatic plants speedily invaded the new habitats, thus
proving that their previous absence from the district was only
due to the absence of natural ponds and lakes, and not to
any climatic reasons.

Most of the aquatic plants in question were not introduced
here intentionally, but spread spontaneously; and these therefore
belong to a different category from such plants as the white
water-lily (Nymphaea alba) which has here and there been
intentionally introduced into the ornamental waters of some
of the parklands, as at Chatsworth.

Many of the canals and mill-dams which harbour these
aquatic aliens are grossly contaminated with mill refuse ; but
a number of lowland aquatic species appear to be peculiarly
unsusceptible to such influences, perhaps because they have
become adapted to life in stagnant and often naturally foul
and badly aerated waters. On the other hand, those aquatic
plants which characterize swift-flowing streams, whose waters
are naturally well aerated and pure, are speedily extirpated
when the waters are rendered foul.

The invasion of the artificial stagnant waters by aquatic
plants of the Pennines is still proceeding ; and quite recently,
an American pond- weed (* Potamogeton pennsylvanicus) has
become established in a canal near Halifax, a little to the
north of the present district. Mr A. Bennett (1908 a) states
that this is the first recorded instance of an alien Potamogeton
becoming established ; but all the Potamogetons of the canals
which cross the Pennines are, in a sense, aliens in these upland
waters.

In a canal near Manchester, a few miles to the west of the
present district, such remarkable alien aquatic species occur as

VI] MARSH AND AQUATIC ASSOCIATIONS 159

*Chara Braunii, *Naias graminea, and *Vallisneria spiralis.
These, as has been recently shown, are confined to certain parts
of the canal where the temperature is more or less permanently
raised by the inflow of heated water from adjoining cotton mills
(Weiss and Murray, 1909), and have no doubt been intro-
duced with imported cotton. * Potamogeton pennsylvanicus,
which, when first discovered in the canal at Halifax, was
thought to be restricted to the water which is heated by the
discharge from cotton mills (Bennett, 1908 a and b), has been
found to have a rather more extended range. This plant also
has in all probability been introduced with cotton from North
America.

It is evident, therefore, that many water plants have ex-
cellent means at their disposal for successful migration. Not
only is this seen from the above-mentioned facts of distribution,
but an experiment (Wheldon and Wilson, 1907 : 339) confirms
this well-established opinion. A pond was made, near Garstang
in North Lancashire, in a grassy field to see which water plants
would appear. The pond was carefully railed off to prevent
access of cattle. After eighteen months, the following plants
had appeared : — Nitella opaca, Callitriche sp., Alisma Plantago,
Glycerin fluitans, Juncus conglomeratus, and J. articulatus.

It may, perhaps, appear surprising that practically no alien
aquatic plants should have become established on the Pennines
in the numerous reservoirs (see figure 36) which have been
constructed at the clough heads during recent years ; but the
reservoirs are artificially kept clear of water " weeds." However,
the only recorded station of the water purslane (Peplis Portula)
in the Peak District is on the south side of the reservoir at
Chapel-en-le-Frith (Linton, 1903: 151).

The following is a list of the aquatic flowering plants of the
ponds, mill-dams, canals, etc. of the southern Pennines. Most
of the species occur only at altitudes below 600 feet (183 m.).
Those which occur at the higher altitudes are indicated by
the letter " U " (= upland) being placed in brackets after ' the
specific name ; and the plants that are not strictly indigenous
are preceded by an asterisk (*): —

160

VEGETATION OF THE PEAK DISTRICT

[CH.

In non-

calcareous

waters

Charophyta

Chara fragilis

—

C. hispida

—

C. vulgaris

Nitella opaca

Angiospermae

Polygonum amphibium

*vr

*Nuphar lutea

—

*Nymphaea alba

—

*Ceratophyllum demersum

—

Ranunculus circinatus

—

E. Sultans

—

R. pseudofluitans

—

R. trichophyllus

—

R. Drouettii

—

R. peltatus (agg.)

—

R. Baudotii

—

"Callitriche verna" (U)

*vr

C. stagnalis (U)

C. hamulata

C. obtusangula

Myriophyllum spicatum

*vr

*M. alterniflorum

—

"Hippuris vulgaris"

*Apium inundatum
*Littorella juncea

—

Potamogeton natans

*P. perfoliatus

—

P. crispus

*vr

*P. obtusifolius

—

*P. zosterifolius

—

*P. pennsylvanicus

—

P. pusillus

*P. Friesii

—

*vr

*P. pectinatus

—

Zannichellia palustris

*vr

*Sagittaria sagittifolia

—

*Elodea canadensis (U)

Lemna minor (U)

*L. trisulca

—

*Heliocharis acicularis

" Catabrosa aquatica "

—

Glyceria fluitans (U)

G. plicata (agg.)

VI ] MARSH AND AQUATIC ASSOCIATIONS 161

THE RELATION OF MINERAL SALTS TO THE FLORA
AND VEGETATION

It will be seen that the differences between the flora and
vegetation of the calcareous and the non-calcareous terrestrial
soils are paralleled by differences between the aquatic and
sub-aquatic flora and vegetation. These differences cannot be
explained by the differences in the physical nature of the
habitat, for, in the case of the two aquatic habitats, the physical
characters are identical. The facts therefore support the view
that the presence of lime-loving plants in calcareous waters
and soils is somehow related to the chemical composition of
the waters (cf. Schimper, 1903: 102). Wheldon and Wilson
(1907: 90) also point out that in addition to water-content,
" another agent also has its influence. On examining the
plant associations of habitats having about the same degree
of humidity, we frequently find the species in them are totally
dissimilar." These authors then go on to give the groups of
species found respectively in boggy ground at the calcareous
shore of a moorland tarn, with Primula farinosa, Cladium
Mariscus, Schoenus nigricans, Juncus obtusiflorus, and Hypnum
falcatum ; of the swampy margin of a pool on the glacial drift,
with Ranunculus Flammula, Bidens tripartita, Alisma Plantago,
Sparganium neglectum, and Hypnum aduncum ; of a peat bog,
with Drosera spp., Andromeda Polifolia, Carex limosa, Myrica
Gale, and Sphagnum spp. ; and of estuarine marshes, with
Spergularia media, Limonium (= Statice), Aster Trifolium, and
Glyceria maritima. As " in all these stations the water supply
is fairly constant and really in excess of plant requirements,
and the conditions of altitude and exposure practically identical,"
the authors " are led, therefore, to the conclusion that some
component of the soil must be the factor which determines ,the
presence or absence of these various species " ; and it seems to
me also that a study of the distribution of plants in any district
where the chemical composition of the soil shows great varia-
tions leads inevitably to the conclusion of Nageli (1865 : 367),
of Schimper (1903 : 101), and many others that the chemical
constituents of the soil, in addition to any or all of the physical

M. 11

162 VEGETATION OF THE PEAK DISTRICT [CH. VI

conditions, have directly or indirectly an enormous influence on
the differential distribution of the flora and vegetation of that
district. Precisely what this influence is, however, is a matter
on which the present state of knowledge in physiological botany
allows no definite statement to be made.

Clements (1907: 18) opposes the "chemical theory" (cf.
Schimper, loc. tit.); and even goes so far as to assert that "it
now appears entirely incorrect to ascribe the presence or absence
of certain species on limestone soils to the chemical nature of
the latter." Without doubt, the " chemical theory " requires
close investigation by modern plant physiologists ; and a re-
statement of the whole position is urgently needed. However,
the study of the vegetation of a district like the present, where
highly calcareous soils occur in close proximity with soils
extremely poor in lime, where the climatic factors obtaining
over the two types of soil are identical, where both habitats
exhibit every transition from wet to dry, and yet where the
flora and vegetation of the two types of habitat show very
marked differences, should convince any observer that the
" chemical theory " is far from being effete.

Hall and Russell (1911 : 54) have recently stated that "soils
devoid of carbonate of lime are never fertile, because without
it the plant food of the soil cannot readily be brought into a
condition available for the plant, and many of the most important
bacterial actions in the soil are dependent on the presence of a
base like carbonate of lime."

Kraus (1911) has recently published some valuable statistical
data bearing on the question; and not until more work has
been performed on these lines will it be possible to reach the
solution of this intricate and much-debated problem.

CHAPTER VII

MOORLAND ASSOCIATIONS

General distribution of moorland. Classification of moorland associations.
The fen formation. " Hochmoor " and " Flachmoor." Moors and
Fens. Bryophytes of the moors. Factors related to the distribution
of the moorland associations. Heather moors. Transitional as-
sociation of heather moor and siliceous grassland. Bilberry moors.
Transitional association of heather moor and bilberry moor. Cotton-
grass moors. Transitional association of cotton-grass moor and
siliceous grassland. Transitional association of heather moor and
cotton-grass moor. Retrogressive moors. The Peak of Derbyshire.
Bare peat. Sub-Alpine grassland. Zonation of the moorland and
grassland associations. List of species of the moor formation.

GENERAL DISTRIBUTION OF MOORLAND

THE moorland associations occur on peat whose waters are
poor in soluble mineral salts and are also acid in reaction. In this
district, the peat is almost wholly confined to the plateaux and
to the upper slopes of the sandstones and shales. Peat also
occurs in places which the existing geological maps indicate as
Carboniferous Limestone ; but most of such localities on exami-
nation prove to have a surface layer of chert (figure 1). Certain
volcanic and metamorphic rocks of the limestone area also bear
moorland plants over limited tracts ; and, as already stated (see
pages 122 — 6), heather (Calluna vulgaris) and some of its associ-
ates are found on leached limestone soils. There are no lowland
peat moors in this district, although they are not rare on the
plains both on the east and west of the Pennines.

The peaty uplands consist of gently sloping plateaux. These
are usually dip slopes, or less often the slopes of the valleys
of small streams. The peat of the lower plateaux is shallow

11—2

164 VEGETATION OF THE PEAK DISTRICT [CH.

and usually dominated by heather (figures 33 and 34 6): the peat
of the higher plateaux is much deeper and usually dominated
by the cotton-grass (figure 33 c). This typical regularity of the
moorland plateaux is, however, frequently broken by alternating
outcrops of sandstone and shale. The outcrops of sandstone are
usually characterized by a preponderance of bilberry (figure d}>
and those of the shale by swamps in which the larger rushes
(Juncus effusus and effusus forma compactus) are generally
conspicuous. The vegetation of these Juncus swamps has
already been described (see pages 146 — 150). Sometimes, even
in the general moorland area, a steep, shaly hill-slope is
characterized by siliceous pasture.

The moorland vegetation ascends to the highest summits
of the district, three of which attain an altitude slightly
exceeding 2000 feet (610 m.). No Arctic or Alpine species
occur anywhere on the southern Pennines, as in the case of
the higher Pennine summit of Cross Fell further to the north
(Lewis, 1904 a: 328; 19046: 279). The vegetation of the
highest plateaux of the Peak District is marked by the
occurrence of retrogressive moors (figures 28 to 31) with much
bilberry (Vaccinium Myrtillus), which very often alternates
with patches of crowberry (Empetrum nigrum), less frequently
of cloudberry (Rubus Chamaemorus), and sometimes of bare
peat.

The altitude to which the moorland vegetation descends is
determined partly by physiographical and partly by artificial
causes. Where the moorland ceases abruptly and is separated
merely by a stone wall from the permanent pasture of the
upland cultivation (see figure 24), the lower limit is simply
the place where reclamation has stopped ; and this limit usually
varies from about 1000 feet (305 m.) to about 1600 feet (488 m.);
but where the moorland adjoins siliceous pasture, the limit is
a perfectly natural one. The latter limit varies from about
750 feet (229 m.) to about 1500 feet (457 m.). Where the
moorland descends to the lower of these altitudes, a zone of
heather moor invariably occurs ; and where the moorland ceases
at the higher of these altitudes, this zone is absent.

In ascending the lateral slope of an upland valley, the change
from the grassy slope to the peaty plateau is rather abrupt,
and the transition region narrow. This is well seen in an

Figure 22.

Heather Moor on peat over Millstone Grit rock.
Heather (Calluna vulgaris) in flower in September.

T. B. Crump

VII] MOORLAND ASSOCIATIONS 165

ascent of the grassy hill sides north:west of Edale railway
station, where the transition occurs at an altitude of about
1500 feet (457 m.). The transitional area is usually characterized
by much bilberry and crowberry. On the other hand, in following
the course of an upland stream to its source, the moorland
plateau is reached very gradually ; and, at the head of the valley,
where a number of very different plant associations converge,
a confused mixture occurs of siliceous pasture, scrub, and moor-
land—a mixture which defies accurate cartographical represen-
tation of the vegetation except on maps of a large scale. In
descending a moorland plateau along the watershed between
two lateral valleys, the moorland vegetation usually comes down
to about 1000 feet (305 m.), and, in a few cases, as at Tintwistle
Moor, near Glossop, to about 750 feet (229 m.).

The rocky, exposed summits of the higher hills (figure 25)
are characterized by the dominance of the bilberry (Vaccinium
Myrtillus). Such bilberry moors are not of great extent ; but
they are interesting as linking the vegetation of the Pennines
with that of central Scotland, where bilberry moors at high
altitudes are widespread (R. Smith, 19006: 461 — 2).

Sometimes the various moorland associations are sharply
marked off from each other. Such sharply defined boundaries
nearly always correspond with well-marked physiographical
features. For example, a cotton-grass moor occupying a high
plateau sometimes ceases quite sharply at an escarpment, on the
plateau below which a heather moor may occur. The rocky
escarpments, like the exposed rocky summits, are characterised
by much bilberry; but the flora of the bilberry edges is richer
than that of the bilberry ridges. Sometimes, however, the
various moorland associations pass into each other very gradually,
as when a heather moor adjoins a cotton-grass moor and there
is not intervening escarpment. In such cases the transitional
region is broad, and is marked by the co-dominance of the
heather and the cotton-grass. On the accompanying vegeta-
tion maps, such transitional areas are indicated by stippling the
colour used for heather moors on the colour used for cotton-
grass moors.

166 VEGETATION OF THE PEAK DISTRICT [CH.

CLASSIFICATION OF MOORLAND ASSOCIATIONS

The moorland plant associations of the district may be
arranged and designated as follows: —

1. Heather moor. Association of Calluna vulgaris (Cal-
lunetum vulgaris).

2. Cotton-grass moor. Association of Eriophorum vagi-
natum (Eriophoretum vaginati).

3. Bilberry moor. Association of Vaccinium Myrtillus
(Vaccinietum myrtilli).

4. Retrogressive moors whose chief constituents are the
bilberry, the crowberry (Empetrum nigrum), and the cloudberry
(Rubus Chamaemoriis). Locally, extensive patches of bare peat
occur.

5. Transitional moors of heather and cotton-grass.

6. Transitional moors of heather and bilberry.

7. Transitional areas of heather and siliceous pasture.

8. Transitional areas of cotton-grass and siliceous pasture.
In other parts of the British Isles, the following additional

moorland plant associations have been recognised.

9. Sphagnum moor. Sphagnum moors are mapped
by Lewis (1904 a: 325). They are also described for north
Lancashire by Wheldon and Wilson (1907 : 102) who state
that this " upland Sphagnum association " has for its dominant
species Sphagnum recurvum, and that this is occasionally
accompanied by other bog mosses, such as S. nitens, S. papil-
losum, and S. rubellum, and still more frequently by Polytri-
chum commune. Frequent members of this association, though
usually marginal or very subordinate, are Viola palustris, Vac-
cinium Oxycoccus, Juncus effusus, Eriophorum angustifolium,
Garex echinata, C. canescens, and locally Rhyncospora alba. One
of the Sphagnum moors mapped by Lewis (op. cit.) has more
recently been visited by the members of the Yorkshire Natu-
ralists' Union (see The Naturalist, 1910: 265 and 313), who
reported, in addition to many other mosses and Hepatics, the
following species of Sphagnum : —

S. rubellum, S. acutifolium, S. subnitens, S. cuspidatum, S. recurvum,
S. inundatum, S. tenellum.

VII] MOORLAND ASSOCIATIONS 167

10. Cotton-grass moor. Association of Eriophorum
angustifolium (Eriophoretum angustifolii).

11. Scirpus moor. Association of Scirpus caespitosus
(= Trichophorum caespitosum) (Scirpetum caespitosi).

These two associations are described by Pethybridge and
Praeger (1905 : 166 — 7), and occur on the Wicklow mountains
south of Dublin. In certain Scottish localities also, namely,
in the north-western Highlands, in the Hebrides, and in the
Shetlands, " Scirpus caespitosus dominates the most character-
istic associations. In Nt W. Sutherland, the flat, basaltic plateau
of northern Skye, and the valley floors and gently sloping hillsides
of Shetland, this type remains dominant over many hundred

square miles In the western portion of N. Uist, the Scirpus

caespitosus association extends over hills of low elevation and
broad shallow valleys " ([F. J. Lewis, in] The New Phytologist,
1908 : 257). Scirpus moors resemble the cotton-grass moors and
heather moors of the Pennines in the comparative scarcity of
bog-mosses (Sphagnum spp.).

12. Rhacomitrium moor. Association of Rhacomitrium
lanuginosum (Rhacomitrietum lanuginosi). Pethybridge and
Praeger (1905 : 167) describe a modification of the heather moor
and the Scirpus moor brought about by the local dominance
of a species of woolly moss (Racomitrium lanuginosum). The
association of Rhacomitrium lanuginosum would appear to be
fairly widespread in western Scotland ; and " Rhacomitrium
bogs" in Caithness are described by Crampton (1911: 55).

All the above associations and societies occur on peat which
is marked by acidic waters, and by a low soluble mineral-
content, especially by a low lime-content. The plant formation
of such a habitat has been termed an Oxodion (Moss, 1910 b :
43) ; and its described chief associations in the British Isles may
be designated as follows (cf. Moss, loc. cit.} : —

Oxodion Calluneti-vulgaris
Oxodion Eriophoreti-vaginati
Oxodion Vaccinieti-myrtilli
Oxodion Sphagneti-recurvi
Oxodion Eriophoreti-angustifolii
Oxodion Scirpeti- caespitosi
Oxodion Rhacomitrieti-lanuginosi

168 VEGETATION OF THE PEAK DISTRICT [CH.

THE FEN FORMATION

In the lowlands of eastern England, peat occurs which is
characterized by alkaline waters, and by a high, soluble mineral-
content, especially by a high lime-content. Such peat bears a
totally different set of plant associations and societies and quite
a different flora; and its vegetation must therefore be placed
in a different formation. The peaty tracts of eastern England
which are characterized by alkaline waters are usually spoken
of by the local inhabitants as " black fens " or simply " fens " ;
and the difference between the two types of peaty vegetation
appears to be of a very fundamental nature. Accordingly, the
vegetation of acidic peat may be said to belong to the moor
formation and that of alkaline peat to the fen formation.

"HOCHMOOR" AND " FLACHMOOR "

Continental plant geographers distinguish two main types
of peat vegetation under the names of " Hochmoor " and
" Flachmoor." In Warming's Oecology of Plants (1909 : 204),
these terms are represented by " high moor " and " low moor "
respectively. These, distinctions do not entirely correspond to
the distinctions of moor and fen adopted by most British plant
geographers. Warming (loc. cit.) gives nine distinctions between
" high moors " and " low moors."

1. "Low moor arises on a surface that is covered with
water.... High moor arises on moist soil or even above water."
On this basis, the moors of the Peak District are " high moors."

2. "Low moor has a flat surface (either horizontal or
inclined). High moor has a convex surface." The cotton-
grass moors of this district have, on the whole, a flat surface ;
and, therefore, if judged from this point of view alone, they
would have to be placed among " low moors."

3. " Low moor is produced particularly by grass-like plants,
including Cyperaceae.. . .High moor owes its origin to bog-mosses,
Sphagnum and others, and includes many Ericaceae." Apply-
ing this test, the heather moors would be placed among the
" high moors," the cotton-grass moors among the " low moors " ;
but this test for low moors is unsatisfactory, as Warming
(p. 202) also includes " grass-like plants," such as Rhyncospora
alba, Carex spp., Eriophorum spp. (especially E. vaginatum), and
Agrostis canina, among the constituent plants of " high moor."

Figure 23.

W. B. Cruntjt

Heather Moor.

Thin peat over Chert on the Limestone Plateau. Associated
with the Heather (Calluna vulgaris) are Hawthorn (Crataegus
Oxyacantlui = C. monogyna) and dwarf Furze (Ulex Galii). In the
background is High Hake and a slope of upland calcareous grassland.

VII] MOORLAND ASSOCIATIONS 169

4. " Low moor water is calcareous. High moor water
contains little or no lime." Judged by this test, which seems
a good one, all the moors of the Peak District are " high moors."
However, some moors placed by some continental phyto-
geographers among Flachmoors are characterized by species
which grow on peat whose water contains little or no lime.

5. "Low moor forms black, amorphous peat High moor

preserves its plants in a higher degree." From this standpoint,
all the moors of this district are " high moors."

6. "Low moor peat is heavy and rich in mineral bodies
(with ten to thirty per cent, of ash). High moor peat is light
in weight and poor in mineral matter (with about five per cent,
of ash)." The peat of this district yields much less than five
per cent, of ash, if silica (Si02) be excluded ; and the application
of this test therefore may be regarded as placing the moors
among " high moors." Peat from Wicken Fen, near Cambridge,
on the other hand, yields more than ten per cent, of ash.

7. "Low moor peat is usually close in texture,... and con-
ducts water badly.... High moor peat... conducts water well."
The upper layers of the peat of all the moors of this district
conduct water well.

8. "Low moor peat is very rich in food-material... High
moor peat... is very poor in nutriment." The peat of this
district is invariably poor in food-material.

9. "On low moor, mycorhiza and carnivorous plants are
rare.... On high moor, mycorhiza and carnivorous plants are
common." On the moors of this district, the only carnivorous
plants to be met with are the sundew (Drosera rotundifolia)
and the butterwort (Pinguicula vulgaris) ; and both are rare.
Mycorhiza occur in the roots of heather (Calluna vulgaris), but
have not been proved to be present in many other moorland
plants of the district. As carnivorous plants (e.g., Utricularia
minor, U. intermedia, and U. vulgaris) occur in the waters of
fens, this test is not very satisfactory. ,

Though some of these tests require re-stating, it seems
fairly clear that the moors of the district belong to the class
of Warming's " high moors " ; and it is clear that some moors
designated "Flachmoors" by continental plant geographers
require re-investigation from the standpoint of the amount of
available food-material contained in the peat.

170 VEGETATION OF THE PEAK DISTRICT [CH.

Tansley (1911 : 208) has recently discussed the conditions
of British moors and fens ; and in his Types of British Vege-
tation, accounts are given of the vegetation of the two plant
formations. The " fenland formation " of Caithness, recently
described by Crampton (1911 : 74), is certainly not true fen,
but a type of vegetation intermediate between fen and moor,
and termed Uebergangsmoor (transitional moor) by Weber
(1908: 95).

MOORS AND FENS

The only test of fen peat and moor peat, which is here
regarded as really fundamental, is that depending on the
amount of soluble mineral matter in the peat; and as this
is very low in the case of all the local peats examined, there
is no difficulty in referring all the plant associations developed
on peat in this district to the moor formation as opposed
to the fen formation.

The following characteristics distinguish the two forma-
tions : —

1. Fen peat is rich, moor peat is poor in soluble mineral
matter.

2. Fen waters are alkaline, moor waters acid in reaction.

3. Fen peat often, moor peat rarely, contains the remains
of molluscan shells.

4. The following plants are locally subdominant or very
abundant on the peaty fens of eastern England: —

Cladium Mariscus Calamagrostis lanceolata

Schoenus nigricans Molinia caerulea

Phragmites communis Juncus obtusiflorus

Of these species, only one — Molinia caerulea — occurs on the
moors of the Peak District.

The following species are locally dominant or very abundant
on British moors : —

Sphagnum spp. Vaccinium Myrtillus

Polytrichum commune V. Vitis-idaea

Rhacomitrium lanuginosum Scirpus caespitosus

Empetrum nigrum Eriophorum vaginatum

Rubus Chamaemorus E. angustifolium

Erica cinerea Carex Goodenowii

E. Tetralix Molinia caerulea

Calluna vulgaris Juncus squarrosus

VII] MOORLAND ASSOCIATIONS 171

Of these species, only Molinia caerulea and perhaps Scirpus
caespitosus occur in the fen formation of Cambridgeshire.

5. The following species also occur (or formerly occurred)
in the fens of East Anglia : those that are local or very rare
are marked by an obelisk: —

Lathyrus palustris C. paradoxa

t Viola stagnina C. lasiocarpa

tV. montana C. lepidocarpa

Peucedanum palustre C. pseudo-Cyperus

t Selinum caruifolium Calamagrostis Epigejos

tSenecio palustris tLuzula pallescens
t S. paludosus Orchis incarnata

t Sonchus palustris Epipactis palustris

Potamogeton plantagineus Habenaria conopsea

Carex disticha + Liparis Loisellii

The following plants are characteristic of British moors,
and are all common or fairly common plants : —

Lycopodium Selago Rhyncospora alba

Blechnum spicant Carex curta

Viola palustris C. echinata

Drosera spp. C. binervis

Galium saxatile Agrostis canina

Arctostaphylos spp. Nardus stricta

Vaccinium Oxycoccus Deschampsia Qexuosa

Andromeda Polifolia Luzula multiflora

Myosotis repens Narthecium ossifragum

Pedicularis sylvatica Listera cordata

Potamogeton polygonifolius Orchis ericetorum

An opinion which is held by many geologists and others to
the effect that moor peat is generally composed of Sphagnum-
moss and fen peat of Hypnum-moss is not supported by an
examination of the plant remains preserved in the peat.

Certain types of vegetation, intermediate in various respects
between moor and fen, require further study. They are usually
characterized by the presence of some of the following species : —

Myrica Gale Pedicularis palustris

Ranunculus Lingua Schoenus nigricans

Potentilla Comarum Triglochin palustre

Parnassia palustris Eleocharis acicularis

Anagallis tenella Scirpus pauciflorus

Menyanthes trifoliata Eriophorum la tifolium

Veronica scutellata Orchis latifolia

172 VEGETATION OF THE PEAK DISTRICT [CH.

BBYOPHYTES OF THE MOORS.

The cryptogamic flora of the various British plant associa-
tions has not yet been fully investigated. During the course
of the present botanical survey, lists have been compiled of
mosses and liverworts ; but the Algae and the Fungi have not
been fully investigated. I have frequently been indebted to
Mr C. Crossland, of Halifax, for help in the identification of
the liverworts and mosses; and I have also found the list of
mosses in the floras by Linton (1903) and Crossland (1904)
of very great service. The following mosses and Hepatics occur
in the moor formation of the southern Pennines : —

Hepaticae

Blepharozia ciliaris Mylia anomala

Lepidozia reptans M. Taylori

L. setacea Jungermannia intiata

Kantia Trichomonis J. sphaerocarpa

Cepalozia lunulaefolia J. crenulata

C. bicuspidata J. ventricosa

C. Lammersiana J. incisa

C. divaricata J. gracilis

Scapania irrigua J. lycopodioides

S. nemorosa Nardia scalaris

Musci Sphagnaceae

S. fimbriatum S. inundatum

S. rubellum S. Gravetii

S. acutifolium S. rufescens

S. subnitens S. crassicladum

S. molle (rare) S. turfaceum

S. squarrosum S. cuspidatum

S. teres (rare) S. recurvum

S. compactum S. cyinbifolium

S. rubsecundum S. papillosum

Polytrichaceae

Polytrichum urnigerum P. juniperinum

P. nanum (rare) P. gracile

P. piliferum P. commune

Copy riyl it

Figure 24.

Heather Moor.
The moor abuts on upland permanent pasture.

W. B. Crump

VIl] MOORLAND ASSOCIATIONS 173

Other mosses

Tetraphis pellucida Leptodontium flexifolium

Dicranella crispa Splachnum sphaericum (on dung)

D. cerviculata Aulacomnium palustre

D. heteromalla Webera nutans

Campylopus flexuosus Bryum pallens

G. pyriformis Mnium subglobosum

C. fragilis Hypnum fluitans
Dicranum Bonjeani H. exannulatum

D. scoparium H. revolvens
Leucobryum glaucum H. falcatum
Rhacomitrium spp. (rare) H. stramineum

FACTORS RELATED TO THE DISTRIBUTION OF THE
MOORLAND ASSOCIATIONS

Factors which appear to be of importance in determining
the various plant associations of the moors are (1) the relative
amounts of sand and humus in the soil, (2) the amount of
water in the soil, (3) the depth of the peat, (4) the altitude
above sea-level, (5) the exposure to winds, (6) the anatomical
structure of the moorland plants, (7) a change in the nature
of the habitat, and perhaps (8) rainfall.

(1) Sand and humus. The peat of the heather moors
yields a much greater quantity of silica (Si02) than the peat of
the cotton-grass moors.

(2) Water. The peat of the heather moors possesses a
much lower physical water-content than the peat of the cotton-
grass moors ; and this fact illustrates the general rule that the
more humus a soil contains the more water it also contains.

It would appear that the insoluble particles of silica are of
some importance in controlling the water-content, and thus of
importance in distinguishing the various associations. Corre-
lated with the water-content is the aeration of the peat ; and
the peat of the heather moor is much better aerated than that
of the cotton-grass moor.

(3) Depth. The peat of the heather moor is shallower
than the peat of the cotton-grass moor. That of the heather
moor varies from a few inches to about four or five feet (122 or
152 cm.), and is commonly about a foot (30'5 cm.) in depth.
That of the cotton-grass moor varies from about three feet

174 VEGETATION OF THE PEAK DISTRICT [CH.

(91 cm.) to about fifteen feet (457 cm.) : commonly it is about
ten feet (30'5 cm.) deep ; whilst locally in hollows these depths
may be exceeded. The lower layers are almost constantly wet,
and hence act as an impervious substratum to the upper layers
which, however, are sometimes very dry in summer owing to
evaporation.

(4) Altitude. The heather moor rarely exceeds 1500 feet
(457 m.) in altitude : the cotton-grass moors ascend to 2000 feet
(610 m.). Between 1500 feet and 1750 feet (533 m.), heather
and cotton-grass frequently share dominance.

(5) Exposure. The exposed ridges and peaks, from
1500 feet upwards, are characterized by an association of
bilberry (Vaccinium Myrtillus}, whilst on the highest plateaux,
retrogressive moors occur.

In general, it may be said that heather moors are found in
the drier, more sandy, shallower, and less elevated regions, that
cotton-grass moors dominate the wetter, purer, and deeper peat
at higher elevations, that bilberry moors occur on the highest
and most exposed ridges, and that the natural drainage result-
ing from the denudation of the peat of the cotton-grass moors
on the highest plateaux and watersheds produces the associa-
tions characterized by Vaccinium Myrtillus, Empetrum nigrum,
and Rubus Chamaemorus.

(6) Structure. The moorland plants possess certain mor-
phological or structural peculiarities which enable them to thrive
in their respective surroundings.

The vegetative organs of Eriophorum vaginatum and E. an-
gustifolium and many of their associates are well provided with
aeration canals which enable the underground parts to respire
although they are embedded in peat which is, during the
greater part of most years, supersaturated with water. Such
plants are neither complete xerophytes nor complete hydro-
phytes, but possess both xerophilous and hydrophilous characters.
This peculiarity of moorland plants has been pointed out by
Warming (1896: 177). They are frequently termed "bog
xerophytes " or " swamp xerophytes " (see also Yapp, 1909 •
275—6).

The root-systems of Galluna vulgaris, Vaccinium Myrtillus,
and Empetrum nigrum are superficial ; and these plants have
no aeration canals. These facts seem to be obviously related

VII] MOORLAND ASSOCIATIONS 175

to the drier habitats of these species as compared with the
habitat of the cotton-grasses (Eriophorum spp.) and their
ecological allies. In the transitional moors of heather and
cotton-grass, the shallow roots of Calluna vulgaris, Vaccinium
Myrtillus, and Empetrum nigrum allow of their growth side
by side with Eriophorum vaginatum whose functional roots
are more deeply embedded in the peat ; for, in summer and
autumn, the upper layers of peat are frequently dry whilst the
lower layers remain extremely wet.

(7) Changes in the habitat. It has already been stated
that the peat on the highest moors is in a state of denudation
and now dominated by Vaccinium Myrtillus, Empetrum nigrum,
and Rubus Chamaemorus. An examination of the plant-remains
composing the peat of such associations proves that the vegeta-
tion was previously dominated, and almost exclusively dominated,
by Eriophorum. The degeneration of an Eriophorum moor
results in the peat becoming drier; and this results in the
dying out of the more hydrophilous species, such as Erio-
phorum vaginatum and E. angustifolium and the successful
invasion of other plants, such as the bilberry, which are
structurally better adapted to the drier conditions.

(8) Rainfall. It would appear that the local differences in
the mean annual rainfall of the different parts of the moorland
area have little or no relation to the local distribution of the
different moorland associations in the Peak District. Generally
speaking, the mean annual rainfall of the moorland area varies
from about 40 inches (102 cm.) per annum to 55 inches (140 cm.)
or rather more. It has been suggested (Smith and Rankin,
1903 : 155) that the areas where the heather (Calluna vulgaris)
is dominant have, on the whole, a lower mean annual rainfall than
the areas over which the cotton-grass (Eriophorum vaginatum)
is dominant ; but, judging from the statistics supplied by Dr
H. R. Mill (see page 25), the suggestion does not appear to be a
fruitful one so far as this district is concerned. It is well known
that the highest local rainfall of a district is not exactly at the
summit of a hill, but some distance to the leeward of that hill.
For example, in the present district, the highest indicated
rainfall (see British Rainfall) is not on the Peak itself, but
m Fairbrook Clough, which is a few miles to the leeward, that
is, to the north-east of the Peak ; and this tract of highest

176 VEGETATION OF THE PEAK DISTRICT [CH.

local rainfall is characterized by a well-developed and typical
heather moor. Again, whilst the vegetation maps of districts
north of the Peak might, if taken by themselves, be held to
indicate that the heather moors were characteristic of the
eastern and not of the western Pennines, it will be seen that
that indication is not borne out by the vegetation maps of the
present district. The comparative dryness of the peat of the
heather moors is to be explained, not by rainfall statistics, but
by the larger proportion of silica mixed with the peat of the
heather moors, and by the greater shallowness of the peat.

HEATHER MOORS

Associations dominated by the common heather (Calluna
vulgaris) are among the most typical plant associations of the
British Isles. In a general way, such associations may be sub-
divided into heaths and heather moors, the former occurring on
soils containing a higher proportion of sand and which are
therefore drier, and the latter on soils containing a higher
proportion of acidic humus and which are therefore wetter.
In general, heaths are characteristic of the south and east of
Britain, heather moors of the north and west. Hence, the
occurrence of heath and of heather moor in this country would
seem to be determined to some extent by climate. The
associations of Calluna vulgaris (see figure 22), which so often
occur as a fringe of the Pennine peat moors, are, on the whole,
heather moors and not heaths, though some of those found at
lower altitudes approximate in character to heaths.

Weber (1908 : 91) suggests that the term moor should be
used only when the peat is 20 cm. or more in thickness and
when there is less than forty per cent, of ash [including silica]
in the peat ; but a too rigid use of these criteria lead to an
artificial classification.

Beginning at Hayfield, what may be called the western
system of heather moors extends northwards for about ten miles
(16'1 km.), their continuity being broken by the narrow but deep
clough formed by Shelf Brook, and by the larger Longden-
dale, formed by the river Etherow. The northern slopes of

VII] MOORLAND ASSOCIATIONS 177

Longdendale are, except at the extreme west, destitute of heather
moors; but the main western Calluna mass runs along the
southern slopes of the dale for six miles, as far as Woodhead.
The most westerly outlier of the heather moors of the Pennines
in this latitude occurs at Bakestone moor one mile to the west
of the boundary of the district. On the Yorkshire slopes of
the hills, beginning at Dunford Bridge, the eastern system of
heather moors extends in a general south-easterly direction for
about sixteen miles, and is continued eastwards of the present
area on to the Sheffield map, no botanical survey of which has
been completed. The central system of heather moors occupies
a region in the upper portions of the valleys formed by the
rivers Derwent and Westend. The eastern heather moors are
about three miles broad on the average, and the western about
one mile broad. This is a response by the vegetation to the
well-known physiographical fact that the eastern slopes of the
Pennines descend more gradually into the plain than the
westerly slopes. The local altitudinal limit of the association,
at about 1500 to 1550 feet (457 to 472 m.), is partly a response to
the severer climatic conditions of the higher and more exposed
summits, and partly to the wetter soil conditions which obtain
on the deeper peat of the higher moors. The latter fact is doubt-
less related in part to the higher rainfall and more frequent
mists which occur in these regions. It need scarcely be stated
that the upper limit of the moorland association of Calluna vul-
garis in no way corresponds with the upper limit of the species,
which, as a matter of fact, ascends to over 2000 feet (610 m.)
in this district (e.g., on Bleaklow Hill); whilst in Scotland
(Hooker, 1884) the species ascends to 3500 feet (1067 m.).

Many outliers or detached areas of heather moors occur, and
are interesting as pointing to a former greater extension of the
region of heather moors, a region which has been greatly re-
stricted by reclamation and conversion into farmland. The
sides of the roads and lanes in such reclaimed areas are fre-
quently tenanted by moorland plants, such as Calluna, vidgaris,
Vaccinium Myrtillus, and Deschampsia flexuosa.

The western Pennines in the north of the Glossop district
are remarkably destitute of heather moors : this is partly due
to the fact that the slopes of the hills in that locality are very
steep and shaly.

178 VEGETATION OF THE PEAK DISTRICT [CH.

The vegetation of the roadsides, the footpaths, the banks
of streams, and the fringe of the heather moors is, in general,
of a grassy nature. In winter, it is possible to distinguish at
a distance of some miles the sinuous course of old footpaths and
bridlepaths by the contrast in colour which the bleached haulms
of the mat-grass (Nardus stricta) make with the surrounding
dark-coloured moorland vegetation.

Ostenfeld (1908 : 887) states that the heather moors of the
Faeroes are always met with on slopes with a southern exposure :
this is not the case with regard to this association on the
Pennines; and the inference is probably to be made that in
the Faeroes, the association of heather moor is near its climatic
limit of distribution.

On some of the more lowland of the heather moors, especially
in sheltered depressions, the bracken (Pteris aquilina) is very
abundant. It is possible that this plant is extending its range
on the moors. Wheldon and Wilson (1907 : 104) state that on
the heather moors of North Lancashire, "where grouse are a
prime consideration, the bracken is mowed periodically at con-
siderable expense, and the heather is then enabled to overcome
all rivals."

There is not a great deal of human interference with nature
on the heather moors, although they are systematically fired by
the keepers every few years. The length of time which elapses
between the periods of firing varies locally, and determines the
height to which the heather grows. On Eyam Moor the heather
is fired about every four years, and therefore does not grow much
more than ankle high. On the remoter moors in upper Derwent
Dale, a period of eight to ten years elapses between the periods
of firing ; and the heather, on some of these moors, is frequently
more than knee deep. For one or two years after the heather
has been fired, the heather moor presents a desolate appear-
ance ; for the heather does not strongly reassert itself until at
least two years have elapsed. The first plant to become con-
spicuous after firing is the bilberry ( Vaccinium Myrtillus). The
latter frequently occurs as a partially etiolated plant under the
dominant heather, where its habit simulates that of Listera
cordata. In such circumstances, however, the bilberry rarely
flowers or fruits. The underground stems and buds of the
bilberry are frequently unharmed by the firing, even when the

Copyriijlit

Figure 25.

Bilberry Moor.
Crest of a hill (1700 feet: m.) occupied by Bilberry (Vaccinium 1

VII] MOORLAND ASSOCIATIONS 179

heather (which has no underground buds) has been completely
killed. Deschampsia flexuosa and Nardus stricta are also fre-
quently conspicuous during the first summer after the firing,
doubtless owing to invasion by seed. As a rule, seedlings of
heather establish themselves immediately and in abundance
after firing; and, when this occurs, the complete and speedy
rejuvenation of the heather moor is assured. The repopulating
of the moor by heather is due to the germination of its minute
seeds which are blown from adjoining heather-clad tracts. This
fact is known to the keepers who therefore do not fire large,
continuous areas in any given year. Seedlings of heather
(Calluna vulgaris) may be found in abundance in places where
the moor was burned during the previous year.

Typical dry heath, which is characteristically developed on
sandy soils throughout the lowlands of England and especially
so in the south and east, does not occur on the Pennines.
Graebner (1901) has shown that this association does not in
North Germany occur in localities where the rainfall is below
28 inches (71 cms.) ; and it would also appear, judging from its
distribution in England, not to be developed where the mean
annual rainfall is above 35 inches (89 cms.).

The following species occur in the less wet, that is, the
typical parts of the heather moors of the southern Pennines: —

Dominant
Calluna vulgaris

Locally sub-dominant
Erica cinerea Vaccinium Myrtillus

Locally abundant

i
Polytrichum spp. Vaccinium Vitis-idaea

Pteris aquilina Galium saxatile

Ulex Gallii Deschampsia flexuosa

Empetrum nigrum Juncus squarrosus

12-2

180 ' VEGETATION OF THE PEAK DISTRICT [CH.

Occasional

Cladonia spp. Potentilla erecta

Lecanora sp. Calluna vulgaris var. Erikae

Dicranum scoparium Molinia caerulea

Campylopus flexuosus Festuca ovina

Webera nutans Nardus stricta

Plagiothecium undulatum Scirpus caespitosus

Blechnum Spicant Pyrola media

Lycopodium clavatum Trientalis europaea

Nephrodium dilatatum Melampyrum pratense (agg.)

Salix repens "Antennaria dioica"

Betula pubescens Agrostis tennis

Quercus sessiliflora Aira praecox

Rumex Acetosella " Carex dioica "

Crataegus Oxyacantha G. Goodenowii

Pyrus Aucuparia C. flacca

Genista anglica C. pilulifera

Lathyrus montanus C. binervis

Polygala serpyllacea Luzula multiflora

Ilex Aquifolium "Listera cordata"
Calluna vulgaris forma incana

Locally, in damp hollows or wherever the soil is wet and
badly aerated, the following additional species may occur: —

Sphagnum spp. Pinguicula vulgaris

/ Polytrichum commune Cirsium palustre

Hypnum spp. Agrostis canina

Lycopodium spp. Eriophorum vaginatum

Ranunculus Flammula E. angustifolium

forma radicans "Scirpus pauciflorus"

"Drosera anglica" Carex echinata

D. rotundifolia C. curta

"Potentilla palustris" C. Goodenowii
Viola palustris var. juncella

Hydrocotyle vulgaris C. flacca

Andromeda Polifolia C. panicea

Erica Tetralix C. flava

Vaccinium Oxycoccus Juncus acutiflorus

Pedicularis sylvatica Narthecium ossifragum

"P. palustris" Orchis ericetorum

' .> v1 i

; ,'

• . .

Figure 26.

Cotton-grass Moor.
Cotton-grass (Eriophorum vayinatum) in fruit in June.

VII] MOORLAND ASSOCIATIONS 181

TRANSITIONAL ASSOCIATION OF HEATHER MOOR AND
SILICEOUS GRASSLAND

Some of the uncultivated areas are intermediate between
heather moor and siliceous grassland. Most commonly in such
places one finds patches of rough grass, such as the mat-grass
(Nardus stricta), silver hair grass (Deschampsia flexuosa), and
bent grass (Agrostis tennis) alternating with patches of heathy
dwarf shrubs, such as heather (Calluna vulgaris), bilberry (Vac-
cinium Myrtillus), and the fine-leaved heath (Erica cinerea).
At other times, one finds a closer but dwarfed growth of the
heathy dwarf shrubs but with a much larger proportion of the
grasses than occurs on heather moor. It is rather rare to
find the cowberry (Vacdnium Vitis-idaea) and the crowberry
(Empetrum nigrum) in this transitional area ; but the combina-
tion does occur. The soil is not peaty, although it contains
more humus (of the acidic type) than is found on siliceous
grassland. Vegetation of this nature is found not infrequently
on the lower sandstone plateaux; and it is quite uncommon
on the steep, shaly slopes. This is a subordinate association
and probably of progressive nature; and it is here regarded
as a stage in the succession from siliceous grassland to heather
moor. On the vegetation maps, it is indicated by stippling the
red colour used for heather on the colour used for siliceous
grassland.

Plants from the neighbouring plant associations and even
plants from the cultivated area invade the heather moor,
especially along the footpaths and streamsides; and, in such
places, the following species sometimes occur mixed with the
heather : —

Urtica dioica (local) Hieracium Pilosella

Rumex Acetosa Taraxacum officinale

Ranunculus bulbosus var. maculiferum

Viola Riviniana Agrostis tenuis

V. lutea (local) (=A. vulgaris)

Polygala serpyllacea Aira praecox

Heracleum spondylium (local) Triodea decumbens

Plantago lanceolata Luzula campestris

Achillaea Millefolium L. vernalis

Bellis perennis (^L. pilosa)
Hypochaeris radicata

182 VEGETATION OF THE PEAK DISTRICT [CH.

BILBERRY MOORS

On the precipitous faces of the dry exposed sandstone rocks,
very few plants occur. A few lichens, especially Parmelia
saxatilis, occur ; and such situations furnish the few remaining
stations of species of the rock-mosses (Andreaea spp.). Sand
and peat, however, find a lodgment on the rock-ledges; and
here a few moorland plants, especially the bilberry ( Vaccinium
Myrtillus), the cowberry (V. Vitis-idaea), and the hair-grass
(Deschampsia fleacuosa), and even a few trees, such as dwarfed
examples of birch (Betula pubescens, and B. pubescens var.
parvifolia), oak (Quercus sessiliflora), and mountain-ash (Pyrus
Aucuparia), find a home. On the screes and boulder-strewn
slopes at the foot of the cliffs, the bilberry and the cowberry
are often very abundant, as well as the crowberry (Empetrum
nigrum) and the bearberry (Arctostaphylos Uva-ursi).

Such Vaccinium associations are exceedingly characteristic
and very largely developed on the rocky slopes surrounding the
Peak (see figure 20).

The bilberry also becomes dominant on the high, bleak, and
wind-swept ridges and peaks of the sandstone hills. Such
Vaccinium ridges have been described by Smith and Moss
(1903: 381), and by Smith and Rankin (1903). As regards
the Peak District, a typical Vaccinium crest is crossed by the
public footpath going from Hayfield to the Snake inn. There is
not very much difference in floristic composition between
Vaccinium crests and Vaccinium edges, but on the former
the cotton-grass and the cloudberry are often abundant, and
the stations of the bearberry seem to be confined to the latter.
If we regard the Vaccinium crest as an association (" Haup-
typus"; Schroter, 1902), then the Vaccinium edge would be
a sub-association (" Nebentypus " ; Schroter, op. dt.).

The following is a list of the characteristic plants of a
Vaccinium edge: —

Dominant
Vaccinium Myrtillus

Locally sub-dominant
Calluna vulgaris Vaccinium Vitis-idaea

W. B. Crump

Figure 27.

Junction of Heather Moor and Cotton-grass Moor.

The dark patches are Heather (Galluna rulgaris), occupying the

better drained parts of the moor. The other vegetation consists

of tufts of Cotton-grass (Eriophorum vaginatum).

VII] MOORLAND ASSOCIATIONS 183

Locally abundant

Pteris aquilina Erica cinerea

Empetrum nigrum Galium saxatile

Arctostaphylos Uva-ursi Deschampsia flexuosa

Occasional or rare

Betula pubescens Pyrus Aucuparia

Quercus sessiliflora Crataegus Oxyacantha

Rumex Acetosella ( = C. monogyna)

Very rare or extinct

"Andreaea alpina" "A. petrophila"

"A. crassinervia "

TRANSITIONAL ASSOCIATION OF HEATHER MOOR
AND BILBERRY MOOR

The areas that are intermediate between heather moor and
bilberry moor are shown on the map by dotting the red colour
used for heaths over the purple colour used for bilberry. Such
areas are usually rocky and peaty, like all the grounds charac-
terized by stable bilberry moors ; but they occur, as a rule, at
rather lower altitudes than the latter.

COTTON-GRASS MOORS

Cotton-grass moors occur on the gently sloping plateaux at
elevations varying, as a rule, from about 1200 feet (363 m.) to
2000 feet (610 m.). These moors are locally termed " mosses " ;
and the place-name "moss," meaning a morass, is by far the
most abundant place-name on the Pennine summits. Smith
and Moss (1903 : 380) and others have therefore used the name
"moss moor," reminding one of the German " moosmoor/' for
this plant association. The place-name "moss," originally of
physiographical significance, has provided the local plant-name
for the chief constituent of the moor whose dominant plant
(Eriophorum vaginatum) is well known to the inhabitants of
the moor-edges as "moss-crops."

The peat of the cotton-grass moors is frequently ten to

184 VEGETATION OF THE PEAK DISTRICT [CH.

fifteen feet (305 to 457 cm.) in depth, and rarely less than five
feet (152 cm.). On rare occasions, as in local hollows and
swamps, it may reach a depth of twenty feet (610 cms.) or more.
The peat is usually saturated and frequently supersaturated
with water, although the superficial layer occasionally becomes
very dry in summer.

Over many parts of the higher moors, Eriophorum vagin-
atum is the dominant plant; and, wherever this plant occurs
in quantity, the depth of the peat is being added to year
by year and denudation of the peat is not taking place. At
the present time, Eriophorum vaginatum probably forms peat
at a more rapid rate and over wider stretches of English moor-
lands than any other plant; and the statement, occasionally
met with, that peat formation is a phenomenon of the past and
not of the present is incorrect.

Bog-mosses (Sphagnum spp.) are even rarer on the cotton-
grass moors than on the heather moors, though a contrary
opinion has gained credence; and the erroneous view is still
met with that the dominance of Sphagnum is a necessary
condition of peat formation. As a matter of fact, Sphagnum
is invariably absent from the peat of true fens, and is by no
means a necessary constituent of the peat of moors. One may
walk many miles over the moors of this district without seeing
any trace of Sphagnum ; and one may examine many sections of
the peat of the district without finding any trace of its remains.

The cotton-grass moors are extensive, dreary, and monotonous.
Eriophorum vaginatum is frequently not merely the dominant
but the only vascular plant which occurs. In late summer and
early autumn, the dead green hue of the shoots of the cotton-
grass is scarcely relieved by any other touch of colour. In late
autumn and throughout the winter, the shoots fade to dull
red; and the vegetation then presents a most forbidding aspect.
A little life is infused into the area in April and May, when the
dusky brown florets make their appearance ; but only in June,
when the pure white fruits of the cotton-grass appear like
suspended snow-flakes, is the cotton-grass moor attractive to
the eye (see figure 26).

The monotony of the cotton-grass moor is, however, relieved
by certain physiographical features to which the vegetation
responds. A sandstone escarpment or outcrop causes a decrease

Figure 28.

If. li. Crumji

Retrogressive Moor.

The moor exhibits early signs of retrogression, as the peat is
being denuded by the stream. The low cliff (2 metres high) of peat
on the extreme left is due to denudation. The vegetation on the
general plateau is Cotton-grass Moor. In the foreground, the
tufts consist of Mat-grass (Nardiis stricta): behind are the broad
leaves of the Cloudberry (Ruins Cluuiuicmorus).

VII] MOORLAND ASSOCIATIONS 185

of the dominant plant, and an increase of less hydrophilous
species, such as the bilberry (Vacdnium Myrtillus) and crow-
berry (Empetrum nigrum). The young shoots of both of these
are, in early spring, frequently characterized by rich tints of
red and brown which enliven an otherwise dreary landscape.
An outcrop of shale is marked by a series of springs, around
which featureless Juncus swamps (see pages 146 to 150) occur.
A steep slope of shale, damp from oozing water, brings about the
vivid greenness of grasses, and locally perhaps of a Sphagnum
swamp. Footpaths, as in the heather moors, are marked by a line
of mat-grass (Nardus strictd), which enables the lonely wanderer
to pick his way and to avoid the quagmires which lurk between
the tufts of the cotton-grass. Calluna vulgaris, Nardus stricta,
Deschampsia flexuosa, and Juncus squarrosus follow the head-
streams almost to their sources.

Ferns and horsetails are absent from all parts of the cotton-
grass moor : club-mosses are extremely rare ; and, whilst species
of mosses, liverworts, Algae, lichens, and Fungi occur here and
there, few are really common, and none is of general occurrence.
The total absence of moorland tarns and valley lakes is not
compensated by the artificial reservoirs which are being con-
structed in the valleys and less frequently on the moors (see
figure 36), as the reservoirs harbour no natural aquatic vege-
tation such as occurs in the Scottish tarns and lochs.

The association of Eriophorum vaginatum is also found
on the lowland " mosses " of Lancashire and Cheshire ; and it
would indeed appear to be specially characteristic of the
moors of northern England.

Ostenfeld (1908 : 947, et seq.) does not describe an asso-
ciation of Eriophorum vaginatum in the Faeroes, though
associations are detailed in which "Eriophorum" and "E. poly-
stachium" (= E. angustifolium) respectively are said to be
dominant. Pethy bridge and Praeger (1905) do not find an
association of Eriophorum vaginatum in the northern Wiqklow
mountains, where, it would appear, associations of E. angusti-
folium and of Scirpus caespitosus hold the same zonal relation-
ship to heather moors that the association of E. vaginatum does
on the Pennines.

The following short list includes all the flowering plants
which have been met with, away from streamsides and

186 VEGETATION OF THE PEAK DISTRICT [CH.

footpaths, in typical examples of the association of Eriophorum
vaginatum of the southern Pennines : —

Dominant
Eriophorum vaginatum

Locally sub-dominant
Molinia caerulea Eriophorum angustifolium

Locally abundant

Empetrum nigrum Vaccinium Myrtillus

Erica Tetralix Scirpus caespitosus

Calluna vulgaris Carex curta

Local or rare

Andromeda Polifolia Pinguicula vulgaris

Vacciuium Oxycoccus Agrostis canina

Narthecium ossifragum

TRANSITIONAL ASSOCIATION OF COTTON-GRASS MOOR AND
SILICEOUS GRASSLAND

It has been already stated that parts of the siliceous grassland
show transitions to the heather moor : such places have a com-
paratively dry soil. Some wet parts of the siliceous grassland
show analogous transitions to the cotton-grass moor. This
transitional association is characteristic of wet and stagnant
hollows. The mat-grass (Nardus stricta) is less abundant here
than on typical siliceous grassland ; and the moor grass (Molinia
caerulea) is frequently conspicuous. Juncus squarrosus is some-
times very abundant ; but in all cases one or other of the two
cotton-grasses, generally E. angustifolium, is the most prominent
plant. Such areas in the Peak District are local in their dis-
tribution. Perhaps the best of them occur between Hayfield
and Chinley. The association probably represents a stage in
the development of cotton-grass moor from siliceous grassland.
On the vegetation maps, they are shown by printing the word
" peat " on the colour used for siliceous grassland

Figure 29.

W. B. Crump

Retrogressive Moor.

The stream has cut through the pe.it into the shales below.

The peat was formerly continuous: it is now dissected into

numerous isolated patches or "peat hags."

VII] MOORLAND ASSOCIATIONS 187

The relationships of siliceous grassland and moorland may be
shown in the following table : —

Nardus grassland

Dry facies

(Deschampsia Jlexuosa or
Agrostis vulgaris abundant)

Wet facies

(Juncus ejfusus

abundant)

Nardus grassland with Nardus grassland with

much heather much cotton-grass

Heather moor Cotton-grass moor

TRANSITIONAL ASSOCIATION OF HEATHER MOOR AND
COTTON-GRASS MOOR

Where the boundary between a heather moor and a cotton-
grass moor is not marked by an escarpment, there is a wide,
level or gently sloping zone in which the heather and the
cotton-grass are co-dominant. These transitional areas are
marked on the vegetation maps by stippling red dots over
the colour used for the cotton-grass moor. A glance at the
map will show that such areas are abundant and widespread,
especially east of Derwent dale and south-west of Buxton.
On many of the latter moors, the cross-leaved heath (Erica
Tetralix) is very abundant. The majority of the associates
of the heather moor are absent ; and because of this fact, and
because of the deep wet peat which occurs, the transitional
moors have, on the whole, more in common with the cotton-
grass moors than with the heather moors. Hence the ground
colour chosen to indicate the transitional moors on the vegeta-
tion maps is that used for the cotton-grass moors. The usual
composition of the transitional moors (see figure 27) is given
in the following list : —

Sub-dominant

i
Eriophorum vaginatum Calluna vulgaris

Erica Tetralix

Locally abundant

Vaccinium Myrtillus Eriophorum angustifolium

Rubus Chamaemorus Scirpus caespitosus

Molinia caerulea

188 VEGETATION OF THE PEAK DISTRICT [CH.

Occasional or rare

Deschampsia flexuosa Narthecium ossifragum

Nardus stricta Pinguicula vulgaris

Moors of this transitional type have been described as
occurring on all portions of the Pennines which have been
investigated.

RETROGRESSIVE MOORS

The bilberry ( Vaccinium Myrtillus), in addition to its being
the chief plant on the screes, edges, and ridges of the sandstone
rocks, also becomes exceedingly prominent on the peat which
is in process of denudation on many of the highest watersheds
and plateaux.

Woodhead (1906 : 351) appears to think that the occurrence
of the bilberry may perhaps always indicate the site of former
forest ; and he quotes Friih and Schroter (1904) almost to the
same effect. This opinion, however, is scarcely applicable to
the Pennines where the bilberry occurs abundantly in situations
which do not resemble its Alpine habitats.

Whilst the peat of the closed association of Eriophorum
vaginatum is still increasing in thickness at a comparatively
rapid rate, and that of the closed associations of heather and
bilberry is also increasing though much more slowly, the peat
on the mpst elevated portions of the moors is gradually being
washed away. This process of physical denudation represents
a stage through which, it would appear, all peat moors, if left to
themselves, must eventually pass. Following Cajander (1904: 1
and 35 — 37), the associations thus formed are termed retro-
gressive [" regressive "] associations.

In the Peak District, the process of retrogression in the
cotton-grass moors is apparently initiated by the cutting back
of streams at their sources. For example, the streams on the
Peak are shown, on the revised Ordnance survey maps (1870 —
1880), to be nearly three-quarters of a mile (1'2 km.) longer
than they were when the Peak was originally surveyed in
1830 ; and they are now a quarter of a mile (0'4 km,) longer
than they are shown to be on the revised maps of 1879. The
channels formed by the streams which have thus eaten their

« ~

PH 0

O -^

VII] MOORLAND ASSOCIATIONS 189

way back have their banks (see figure 29) fringed with sloping
banks of bare peat. In times of drought, the bed of these streams
contains very little water which may temporarily disappear ; but
after heavy rain-storms, the stream is a rapid torrent of brown,
peaty water. Every storm results in quantities of peat being
carried away, in the stream winning its way further back into the
peat, and in the channels becoming wider and deeper. Numerous
tributary streams also are formed in course of time; and
eventually the network of peaty channels at the head coalesces
with a similar system belonging to the stream which flows
down the opposite hill-side. The peat-moor which formerly
was the gathering ground of both rivers, is thus divided up
into detached masses of peat, locally known as " peat-hags "
(figure 31) ; and the final disappearance of even these is merely
a matter of time.

It is obvious that this process results in a drying up of the
peat of the original cotton-grass moor ; and it is most interesting
to trace a series of degradation changes of the now decaying
peat moor. The first change of importance of the vegetation
appears to be the dying out of the more hydrophilous species,
such as Eriophorum vaginatum and E. angustifolium, and the
increase, on the summits of the peaty "islands" or "peat-hags,"
of plants, such as Vaccinium Myrtillus and Empetrum nigrum,
which can tolerate the new and drier soil conditions.

The composition of the upper layers of the peat of these
retrogressive moors has, during the course of the present in-
vestigation, been carefully examined; and it has been found
that the peat consists in its upper layers almost wholly of the
remains of Eriophorum. The succession therefore of cotton-
grass moor to the series of retrogressive moors here being
described, is established beyond doubt.

THE PEAK OF DERBYSHIRE

. As the Peak of Derbyshire is covered by retrogressive
moorland, a short description of this the most important
topographical feature of the district will not be out of place
at this juncture (cf. figure 32).

The Peak is a plateau of Kinderscout sandstone varying in
height from about 1750 feet (533 m.) at its eastern extremity

190 VEGETATION OF THE PEAK DISTRICT [CH.

to 2088 feet (636 ra.) at Soldier's Lump. The latter is the
highest altitude attained by any Pennine summit south of the
Great Whernside group. The Peak occupies an area of about
three square miles (nearly 80 ares). It is clad throughout its
entire length and breadth with peat which is about twelve feet
(363 cm.) deep on the average. The peat is dissected by very
numerous stream channels, formed in the manner just indicated.
The summits of the resulting " peat-hags " are, on the whole,
dominated by the bilberry ( Vaccinium Myrtillus) ; but the crow-
berry (Empetrum nigrum) and the cloudberry (Rubus Chamae-
morus) are locally very abundant, forming plant societies. Here
and there extensive patches of bare peat occur.

The bulk of the peat, all in fact except the lowest layer, is
composed of the remains of the cotton-grass. The lowest layer
is black, very much compressed, and very deficient in air. When
wet or damp, this layer is slippery, like wet soap, to the touch :
when dry, it is sometimes brittle and shiny, not altogether
unlike Whitby jet. Such peat, which is typical of the highest
peat moors, is quite structureless ; and one can only speculate
as to the plants of which it is the remains. On the sandstone,
underneath the peat, there is a thin layer of brittle, reddish-
brown ferruginous " pan " (" Raseneisenstein ") : on the shale,
however, true " pan " (" Ortstein ") occurs below the peat (cf.
Tansley, 1911 : 103). Remains of trees have not been found
on the plateau of the Peak, but only on its slopes, where
remains of birch were noted in a gully at an elevation of
about 1800 feet (549 m.).

The Peak is not an imposing mountain. Viewed from the
east or south, only its grassy slopes can be seen. From Ashop
dale, on the north, the Edge, as it is called, of sandstone rock
stands out rather boldly. From the west, the steep and rocky
slopes of Kinderscout provide a wild and picturesque landscape.
This view is especially fine, in the spring when the young
red and green shoots of the bilberry, and in the autumn when
the richer brown and golden colours of the dying fronds of the
bracken contrast with the sombre green of the heather and
crowberry and the forbidding blackness of the precipices and
large and loosely scattered boulders. Only on the Glossop and
Sheffield high road, at its highest elevation four miles out of
Glossop, may a general view of the summit be obtained ; and

03 ~
« =
PH .;

CO 0> ^ i—

.±P K H

.2 c

VII] MOORLAND ASSOCIATIONS 191

this, the only view obtainable of the summit as a whole, is dull
and uninspiring in the extreme.

From the standpoint of floristic botany, the Peak is un-
interesting ; still, it is of interest to the ecologist as it provides
many problems in the succession of plant associations.

The following plants occur on the plateau or uppermost
slopes of the Peak: —

Dominant species
Vaccinium Myrtillus

Locally sub-dominant species

Kubus Chamaemorus Empetrum nigrum

Vaccinium Vitis-idaea1

Occasional or locally abundant species

Potentilla erecta1 Nardus stricta1

Galium saxatile1 Eriophorum angustifolium

Calluna vulgaris1 Juncus squarrosus1

Molinia caerulea1 J. effusus2

Local or rare species

" Lycopodium spp." Deschampsia flexuosa1

Blechnum spicant1 Scirpus caespitosus1

Nephrodium dilatatum1 Eriophorum vaginatum

" Arctostaphylos Uva-ursi" "Carex dioica"

Erica Tetralix1 C. curta

Festuea ovina1 "Listera cordata"

BABE PEAT

As the process of peat-denudation proceeds, the members of
this retrogressive plant association gradually succumb to the
changing conditions, until the "peat-hags" become almost or
quite bare of plants. At this stage, there is nothing to hold
the peat together; and it is washed and whirled about by
every rainstorm, and by the waters of melting snow. Such bare
peaty summits are of great extent on Black Hill, Holme Moss
(cf. Smith and Moss, 1903: 382), on parts of the plateau of
the Peak, and occur to a greater or less extent on most of
the exposed summits of the Pennines. Almost the only plants

1 Chiefly at the edges of the Peak. - Confined to stream sides.

192 VEGETATION OF THE PEAK DISTRICT [CH.

to be found on such extremely decadent moors are a few
straggling and miserably developed specimens of Eriophorum
angustifolium. The words " Bare peat," printed on the vege-
tation maps here and there, roughly indicate the spots where
the more extensive of the tracts occur such as are here described.

As has been stated, an examination of the peat deposits
underlying the retrogressive peat- moors here described proves
that it is composed almost wholly of the remains of cotton-grass ;
and the living Vaccinium and Empetrum which crown the
" peat-hags " rest unconformably — as the geologists would say
— on strata of cotton-grass peat. Hence the conclusion may be
safely drawn that the retrogressive phases characteristic of the
highest Pennine plateaux are very recent in origin, and, in all
probability, have been initiated during the last few centuries.
The process is still at work, and is likely to become more and
more pronounced as time goes on.

The decadent condition of many of the summits of the
Pennine peat moors make it an easy task to determine that
the ancient Pennine forest did not, at any period, spread over
the highest summits ; as, although the base of the peat is very
frequently exposed, remains of timber have nowhere been found
on the highest summits. In addition to the examination of
the peat which is being denuded on the high summits, several
sections have also been cut with the spade, and with the same
negative results. The retrogressive changes appear, in many
cases, to be spreading downwards into the lower cotton-grass
moors ; but many of the latter show no signs of degeneracy as
yet. The heather moors also are generally speaking in a state
of stability at the present time.

On the vegetation maps, the more pronounced of the retro-
gressive moors are indicated by the hatching of red lines on the
Eriophorum colour. It is reasonable to use this ground colour
as the evidence shows the moors to have been Eriophorum
moors until quite recent times, and the retrogressive changes
are still in operation. Owing to the comparative inaccessibility
of these moors, the absence of landmarks upon them, the absence
of contour lines on the six-inch Ordnance maps, and the im-
permanent nature of the plant association, the boundaries of
these retrogressive moors were difficult and in many cases
impossible to fix with accuracy.

Figure 32.
Map of the Vegetation of the Peak of Derbyshire.

1. Land under cultivation (permanent pasture).

2. Siliceous grassland.

3. Heather moor (Callunetum vulgaris).

4. Bilberry moor (Vaccinietum myrtilli).

^^~— ~_\ 5. Cotton-grass moor (Eriophoretum vaginati).

6. Ketrogressive moor (chiefly bilberry and crowberry,
with patches of cloudberry).

The rocks consist entirely of sandstone and shales (Pendlesides
and Millstone Grits).

VII] MOORLAND ASSOCIATIONS 193

SUB-ALPINE GRASSLAND

In the end, the retrogressive changes outlined above result
in the complete disappearance of the peat ; and on the surface
thus laid bare, a new set of species begins to invade. In this
invasion the ordinary inhabitants of the surrounding peat-
moors can take no part; and the successful invaders are the
more hardy members of the Nardus grassland. As has been
stated (see page 185), such plants follow the streams of the
peat-moors almost to their sources ; and hence they are the
plants which one would expect to be the first to establish
themselves in the newly formed habitat. The summit of
Bleaklow Hill, four miles north of the Peak, is tenanted by
an open plant association which has almost certainly originated
in the way just described. On the summit of Great Whernside
and other hills of the mid-Pennines, Smith and Rankin describe
an association which seems to be capable of a similar interpre-
tation : " the summit-ridge from the edge of the peat-bog
upwards is rocky, with a scanty soil which supports a meagre
vegetation consisting of grasses. Here and there are patches
or islands of peat" (Smith and Rankin, 1903: 154).

The following species were observed on the summit of
Bleaklow Hill:-

Nardus stricta Rumex Acetosella

Deschampsia flexuosa Potentilla erecta
Festuca ovina ( = P- Tormentilla)

Agrostis vulgaris Calluna vulgaris

Juncus squarrosus Vacciniuin Myrtillus

Luzula erecta Qalium saxatile

On Great Whernside, Smith and Rankin (loc. cit.) record
Festuca ovina forma vivipara and Poa alpina ; and it is not
impossible that a careful search on Bleaklow Hill would reveal
these plants, although they have not yet been recorded for
Derbyshire.

The case of this sub-Alpine Pasture illustrates the im-
portant principle that a succession of plant associations, once
initiated, may lead from one plant formation to another (cf. Moss,
19106: 37). In the case under discussion, the retrogressive
succession began in the closed cotton-grass association, continued

M. 13

194 VEGETATION OF THE PEAK DISTRICT [CH.

through the retrogressive associations of bilberry, and, as regards
the moorland formation, ended with bare peat. This open phase
of a retrogressive series of changes terminates a formation, just
as, in a progressive succession an open association is the starting
point of a formation. In the case under consideration, however,
the succession has not ended with the terminal association of
the moorland formation, but has been continued by an open
grassland association. What the future of this succession will
be is a matter of speculation; but one may easily imagine,
assuming climatic conditions to remain unaltered, that the
future of this succession will show a closed association of grass-
land, of mixed grassland and heath, and later, in the still more
distant future, of some moorland association.

The matter of this succession has been discussed here at
some length in order to show that it is possible to account for
the changes which the moorland vegetation has in comparatively
recent times undergone, on other than climatic grounds.

ZONATION OF THE MOORLAND AND GRASSLAND ASSOCIATIONS

The zonation of the moorland and grassland associations of
the non-calcareous summits and slopes of the southern Pennines
is exceedingly well marked, as a study of the vegetation maps
will themselves testify. In a general way, the zonation of plant
associations on any mountain illustrates the effects of altitude
on vegetation ; but these effects are usually modified to some
extent by some local conditions. In this district, the local
conditions which compete with altitude in modifying the zona-
tion are chiefly physiographical in character. However, the
combined effects may be stated in general terms, if one speaks
of the broad outlines of the vegetation and ignores details.

Those eminences which are capped by a fairly flat plateau
are characterized by summits which are covered with retro-
gressive moorland associations (figure 33, a). These retrogressive
associations are surrounded by rocky escarpments covered with
stable associations of bilberry (figure 33, 6). More pointed
eminences are capped by a stable bilberry moor (figure 34, b).
The bilberry moors are surrounded by moderately elevated,
shelving plateaux of only moderate steepness; and on these
plateaux a broad zone of cotton-grass moors (figures 33 and

VII]

MOORLAND ASSOCIATIONS

195

17 50 feet

1 500 feet

1 250 feet

1000 feet

Figure 33. Diagram of the vegetation of a flat-topped eminence
reaching an altitude of about 2000 feet (610 m.), e.g., the Peak.

1250

1500 <

b
17 50 feet

c
'eet

feet

1000 feet

Figure 34. Diagram of the vegetation of a more pointed eminence
reaching an altitude of about 1750 feet (533 m.), e.g., Mill Hill,
near Hayfield.

a. Retrogressive moorland associations.

b. Bilberry moors.

c. Cotton-grass moors.

d. Either heather moors or siliceous grassland.
I-. Upland cultivation.

13—2

VEGETATION OF THE PEAK DISTRICT

[CH.

34, c) is developed. The plateaux of the cotton-grass moor
either descend gradually into the zone of upland cultivation
(figures 33 and 34, e), in which case these two zones are
separated by a zone of heather moor (figures 33 and 34, d) ;
or they are terminated abruptly by steep shaly slopes, in which
case the zones of cotton-grass moor and upland cultivation are
separated by a zone of Nardus grassland (figures 33 and 34, d).
The relationships of the plant formation of the siliceous soils
and that of the moors may be seen in the following table : —

Sub- Alpine Grassland

Bare Peat

Bilberry Ridges $
Retrogressive Moors ~*

OXODION

SILICION

Cotton-grass Moors

Heather Moors

Nardus Grassland Molinia^.Grassland

I with much Heather,

Nardus Grassland ^Birch Woods (B. pubescens}
Scrub

Oak Woods (Q. tessilijlora)

LIST OF SPECIES OF THE MOOR FORMATION

The following species occur on the moor formation (cf.
Ostenfeld, 1908 : 947 et 956) of the southern Pennines ; and
their relative frequency in the three chief associations is also
indicated. The plants preceded by an obelisk have not been
recorded from the Peak District ; but they occur a few miles to
the north.

VII]

MOORLAND ASSOCIATIONS

197

Heather

Bilberry

Cotton-

moor

grass moor

Sphagnum spp.

Polytrichum spp.

—

Hypnum spp.

—

Lycopodium spp.

—

t Selaginella selaginoides

—

Blechnum spicant

r to o

—

Pteris aquilina

r to la

r to o

Nephrodium aristatum

—

Salix repens

—

Betula pubescens (dwarfed)

—

Quercus sessiliflora (dwarfed)

—

Rumex Acetosella

r to o

—

K. Flammula

—

"Drosera anglica"

—

D. rotundifolia

—

Potentilla erecta

( = P. Tormentilla)

r to o

—

"P. palustris"

—

Rubus Chamaemorus

—

r, la

r, Is

Crataegus Oxycantha

( = C. monogyna) (dwarfed)

—

Pyrus Aucuparia (dwarfed)

—

Genista anglica

—

Ulex Gallii

—

Lathyrus montanus

—

Polygala serpyllacea

—

Empetrum nigrum

Ilex Aquifolium (dwarfed)

—

Viola palustris

—

Hydrocotyle vulgaris

—

t Pyrola media

—

Andromeda Polifolia

—

Arctostaphylos Uva-ursi

—

Erica cinerea

0 to 8

—

E. Tetralix

—

Calluna vulgaris

var. Erikae

—

forma incana

—

Vaccinium Myrtillus

o to s

V. Vitis-idaea

V. Oxycoccus

—

tTrientalis europaea

—

Melampyrum pratense
Pedicularis sylvatica

r
1

"P. palustris"

—

Pinguicula vulgaris

—

Galium saxatile

—

Cnicus palustris

—

198

VEGETATION OF THE PEAK DISTRICT [CH. VII

Heather

Bilberry

Cotton-

moor

grass moor

Agrostis canina

A. tennis

( = A. vnlgaris)

—

Aira praecox

—

Deschampsia flexuosa

o to a

—

Molinia caerulea

r to o

r, Is

Festuca ovina

r to o

Nardus stricta

r to o

Eriophorum vaginatum

E. angustifolium

( = E. polystachiom)

—

Scirpus caespitosus

—

"S. pauciflorus"

—

"Carex dioica"

C. echinata

( = 0. stellulata)

—

C. curta

C. Goodenowii

var. juncella

C. flacca

( = C. glauca)

C. pilulifera

—

C. panicea

C. binervis

C. flava

forma minor

Luzula erecta

forma congesta

r to o

Juncus squarrosns

—

J. efFusus

J. articulatus

(=J. acutiflorus)

Narthecium ossifragum

Orchis ericetorurn

"Listera cordata"

?ext.

—

CHAPTER VIII

CULTIVATED LAND: CULTURE ASSOCIATIONS

Origin of the cultivated land. Nature of the cultivated land. Permanent
pasture. The arable land. Plantations. Afforestation. Utilization
of the peat-moors.

ORIGIN OF THE CULTIVATED LAND

THE whole of the land now fenced and under cultivation
was, of course, originally occupied by spontaneous plant asso-
ciations. Of these, those that once covered the land now
cultivated were in all probability of the nature of woodland
in prehistoric and even in early historic times.

Most of the land below about 900 feet (274 m.) has been
cultivated for many centuries ; but there is historical evidence
which shows that, during the last century and a half, con-
siderable intakes at altitudes up to about 1500 feet (457 m.)
have taken place. Whilst the process of reclamation is, to
a slight extent, still proceeding, the modern attempts in this
direction are of a local and intermittent character. These
attempts are nearly all made at the expense of grassland or
the lower fringe of the moorland.

NATURE OF THE CULTIVATED LAND

Almost the whole of the cultivated land of this district is
laid down to grass, and is termed by English agriculturists " per-
manent pasture," as it is nowadays never ploughed. Ploughed
or arable land is, on the whole, of rather uncommon occurrence.

The cultivated land is separated by fences constructed of
either sandstone or limestone. The sandstone walls ultimately
weather to an almost black hue, whilst the limestone walls

200 VEGETATION OF THE PEAK DISTRICT [CH.

remain white ; and the presence of black or white stone fences
is a convenient indication as to whether one is in the area of
sandstone or of limestone respectively.

Hedgerows in the Pennine district are rare, and only occur
where the shales are of great superficial interest, as, for example,
near the confluence of the rivers Noe and Derwent.

At its upper limit, the permanent pasture frequently abuts
on the uncultivated grassland. A distinction is made on the
Ordnance maps between "land under cultivation" and "land
not under cultivation"; but, at and near the upper limits of
cultivation, the boundaries shown on the Ordnance maps are
not always reliable. A comparison of the boundary line between
cultivated and uncultivated land as shown respectively on the
Ordnance maps and on the accompanying vegetation maps will
reveal rather considerable discrepancies.

I am unaware of the principles used by the Ordnance
surveyors in making this distinction. In the present vegeta-
tion survey, the plan has been to make lists of the species of
the difficult tracts, and compare the lists thus made with lists
of tracts which are indubitably uncultivated or cultivated, as
the case may be. There are, without doubt, many areas with
regard to which there may be differences of opinion as to whether
or not they should be mapped as land under cultivation ; but
this does not explain all the details of the mapping of the
Ordnance surveyors, who, indeed, are sometimes very incon-
sistent even on the same " six-inch " quarter-sheet.

On the accompanying vegetation maps, the grassland not
considered to be cultivated, although it may be more or less
grazed, is coloured as siliceous grassland when the flora contains
many heath-loving or humus-loving species, and coloured as
calcareous grassland when there are many lime-loving species
present. These two associations or groups of associations have
been discussed in the chapter on grasslands. Some of the
enclosed fields have apparently once been cultivated and have
been allowed to become derelict; and such areas, by the in-
vasion of plants from the uncultivated land, gradually approach
in character to the neighbouring subspontaneous or spontaneous
associations. However, up to about 1250 feet (379 m.) the
cultivated fields may generally be kept in good condition
without much difficulty ; and one frequently sees, even at the

VIII] CULTIVATED LAND : CULTURE ASSOCIATIONS 201

very edge of a Calluna moor, bright green permanent pasture
which shows no tendency to revert to its original state (cf.
figure 24).

During the course of this survey, the process of reclamation
has been observed in a few cases. The plan adopted was as
follows. The original vegetation, whether heather (Calluna
vulgaris) or grasses (Nardus stricta, etc.) was first burned, and
then cleared of large stones. The land was afterwards ploughed
and limed, and finally planted with oats. The field sometimes
remained a patch of arable land ; but more frequently, grasses
were sown in the second or third years, and the land kept down
to permanent pasture. In some cases, but by no means all, the
land was also drained by means of trenches and agricultural
drain pipes. Where the original land was covered with shallow
peat, the peat was flaked off before the land was ploughed.
Deep peat on these uplands is practically never reclaimed ;
and hence the soil of the cultivated uplands is rarely black,
though it may be of a very dark brown colour owing to its
high humus-content.

Even on the upland tracts which are now almost wholly
cultivated, it is frequently possible to form definite and accurate
ideas regarding the nature of the natural plant associations
which were formerly characteristic of the places in question ;
for some of the indigenous speci.es often linger in some not
wholly unsuitable localities. Such places are the grassy or
heathy banks and sides of the roads and lanes which are not
much frequented, quarries, gravel pits, refuse heaps of old
mines, old hedgerows, hedgebanks, hedgebottoms, and the banks
of streams. Although such localities usually contain a mixture
of indigenous and alien plants, it is seldom impossible to decide
to which of these categories a given species belongs.

The farms of the district are of small size, and rarely consist
of more than forty or fifty acres (1620 or 2025 ares). It is said
by some of the farmers that rather more land was under the
plough some forty years ago ; but the district as a whole has
never been important in the matter of corn growing. Before
the days of cheap flour, probably each farm produced its own
oatmeal at least; but there is no evidence to show that
any crop of the district was ever of more than domestic
importance.

202

VEGETATION OF THE PEAK DISTRICT

[CH.

PERMANENT PASTURE

The permanent pasture, although nowadays never ploughed,,
is an artificial plant association or group of artificial associations.
Human influence is seen in three ways. First, most of the
permanent pasture has been ploughed at least once, and in
many cases has been sown with grass seeds, and the original
plant associations have therefore been destroyed : secondly, it is
more or less regularly manured by the occupying farmers : and
thirdly, it is always grazed over by cattle, horses, or sheep.

The manuring and grazing effectually prevent many of the
aboriginal species re-migrating into the area. However, when
permanent pasture becomes neglected and derelict, these species
tend to enter the area and the introduced species tend to die
off. Ultimately, the derelict pastures are indistinguishable
from the uncultivated grassland ; and they are therefore so
coloured on the accompanying vegetation maps.

Many of the cultivated grass fields are utilized solely for
grazing purposes. In a considerable number of cases, however,
the cattle are kept out of the fields after April ; and the grass
is allowed to grow long, when it is cut for hay. In this district
haymaking usually begins about the end of June and continues
until the middle or end of August, or into September if the
season is unpropitious. By way of a phenological comparison,
it may be stated that in eastern Somerset, haymaking begins
at the end of May or the beginning of June. After the hay
has been cut, the cattle are again turned into the fields ; hence,
it is scarcely possible to make any distinction on the maps
between "meadows" and "pastures."

The most abundant grasses of the hay-fields are : —

Agropyrum repens
Alopecurus pratensis

a
a

Dactylis glomerata
Festuca rubra

a
a

Anthoxanthum odoratum

Loliuru perenne

Phleum pratense

Poa pratensis

Bromus mollis

P. trivialis

Cynosurus cristatus

Trisetum flavescens

Of the above grasses, Cynosurus is characteristic of the drier
and poorer soils, and Trisetum of the damper and richer soils.

VIII]

CULTIVATED LAND: CULTURE ASSOCIATIONS

203

The plants in the following list are mostly counted as
" weeds " by the farmer. They are most abundant in the fields
bordering on the uncultivated land, which are less frequently
and less regularly manured than the fields at lower levels.
Most of the species are really indigenous to the district, and
would perish if the fields in which they occur were manured
more systematically. The list contains most of the species of
the more upland permanent pastures on the sandstones and
shales, although, owing to the manuring, there is no great
difference between the permanent pastures of the sandstones
and shales and those of the limestones: —

In drier pastures

In damper pastures

Ophioglossum vulgatum
Pteris aquilina
Eumex Acetosella
Polygonum Bistorta
Cerastium vulgatum
Potentilla erecta
P. procumbens
Lotus corniculatus
Trifolium medium
Lathyrus montanus
Hypericum pulchrum
Viola lutea
Pimpinella Saxifraga
Veronica officinalis
Euphrasia officinalis
Rhinanthus Crista-galli
Plantago lanceolata
Galium saxatile
Campanula rotundifolia
Centaurea nigra
Chrysanthemum Leucan-

themum

Leontodon hispidum
Crepis virens
Hieracium Pilosella
Agrostis vulgaris
Briza media
Festuca ovina
Luzula campestris

*Rumex alpinus
Stellaria graminea
Ranunculus repens
R. bulbosus
R. acris

Saxifraga granulata
Alchemilla pratensis
Sanguisorba officinalis
Trifolium repens
T. pratense
Anthriscus sylvestris
Heracleum Sphondylium
Conopodium majus
Prunella vulgaris
Ajuga reptans
Veronica Chamaedrys
Achillaea Ptarmica
A. Millefolium
Bellis perennis
Senecio Jacobaea
Hypochaeris radicata
Leontodon autumnale
Taraxacum officinale
Holcus lanatus
Deschampsia caespitosa
Carex ovalis

*Narcissus Pseudo-narcissus
*Crocus nudiflorus

Near the upper limits of cultivation, the manuring often
consists of dressings of lime or of farmyard manure ; and it is
only as the lowlands are approached that chemical manuring
is freely utilized.

204 VEGETATION OF THE PEAK DISTRICT [CH.

THE ARABLE LAND

In previous accounts of the vegetation of districts in Great
Britain, it has been customary to give a table, taken from the
official Agricultural Returns, showing the amount of the various
types of the agricultural land of the county in which the district
is situated. In the case of the Peak District, such a course is
undesirable, as the land consists of portions of five counties and
is very far from being typical of any one of them. Of the various
English counties, the Peak District most nearly resembles West-
morland (cf. Lewis, 1904 a : 316) in its high percentage of
uncultivated land, and in its low percentage of arable land,
especially of land under wheat.

At the present time, it is possible to sub-divide the culti-
vated land of the British Isles into three zones (cf. Moss, 1907 a
or b: 21, 59, 66). The lowest of these zones, occurring as a rule
below fifty feet (15 m.) above sea level, consists of alluvial land :
in the west of England (Moss, 1907 a or b : 21), this alluvial
zone of cultivation is nearly all under permanent pasture ; but
in East Anglia, it is nearly all under arable cultivation, with
wheat entering into the rotation. The intermediate zone,
situated as a rule below six or seven hundred feet (183 or
213 m.) above sea level, consists largely of permanent pasture
in the west and north of England : it shows a higher pro-
portion of arable land, with wheat entering into the rotation,
in the Midlands and in the south of England ; and it consists
very largely of arable land, with wheat, in East Anglia. The
uppermost zone, situated as a rule above six or seven hundred
feet above sea-level, consists largely and in many localities
almost wholly of permanent pasture ; and in the arable land
that actually occurs, wheat does not enter into the rotation,
or, if so, it is a crop of a precarious nature.

In the Peak District, no zone of alluvial cultivation occurs ;
but it has been found possible to show on the map the inter-
mediate (or wheat) zone and the uppermost (or no-wheat) zone :
a transitional zone is indicated on the map by stippling. There
can be no doubt that the dividing line between the wheat and
the no-wheat zones is drawn on the vegetation maps with con-
siderable accuracy. In several cases, upland fields of wheat

VIII] CULTIVATED LAND: CULTURE ASSOCIATIONS 205

have been closely observed during a series of years in order
to determine the effect of good and bad seasons on the ripening
of the grain at or near the upper limit of wheat cultivation.
For example, several wheat fields in Derwent dale and in the
Hope valley were uncut on October 30th, 1906 ; and, after such
a date, wintry types of weather may, in this locality, be expected
at any time, and actually came in early November in 1910.
It is clear therefore that the wheat fields of the locality in
question represent the upper climatic limit of wheat in the
Peak District. Generally it is claimed for the vegetation maps
of Great Britain that they represent the limits of wheat culti-
vation more accurately than has been done on any other maps
in any country or at any time; and, from this point of view
alone, the maps are of great value.

The upper limits of wheat cultivation in the southern
Pennines vary somewhat on the different soils. On the
eastern plateaux of the Coal-measures, wheat is usually grown
up to 700 feet (213 m.), rarely up to 900 feet (274 m.), and
most rarely up to 1000 feet (305 m.). On the Pendleside (or
Yoredale) shales and river gravels in the Hope and Derwent
valleys, wheat is usually grown up to 600 feet (183 m.) and
rarely up to 850 feet (259 m.). On the Millstone grit, wheat
is rare generally, and has not actually been observed higher
than 500 feet (152 m.). On the Mountain Limestone, not a
single case of wheat cultivation has been observed. On the
other hand, oats (Avena) is not infrequently grown on all the
soils up to 1250 feet (381 m.) and more rarely up to 1350 feet
(411 m.). Oats are much more commonly grown on the lime-
stones than on the sandstones. Cereal crops, other than wheat
and oats, are quite rare. Barley (Hordeum) is rarely grown,
and rye (Lolium) scarcely at all. In the no-wheat zone, the
rotation is of a very primitive character, oats being often
grown several years in succession, or, more rarely, in a two-
fold rotation with roots, usually turnips (Brassica). In the
wheat zone, the usual fourfold rotation — wheat, roots, oats,
clover (Trifolium) — is frequently followed.

From the above facts, it will be seen that wheat is cultivated
up to its local climatic limit, but that this varies on the differ-
ent soils, being highest on the shales of the Coal-measures
and Pendlesides and lowest on the Millstone Grit and the

206 VEGETATION OF THE PEAK DISTRICT [CH.

Limestone. Oats are apparently less responsive to soil factors,
and are grown on all classes of soils. On any given soil, the
dividing line between the wheat and the no- wheat zone repre-
sents a limit determined by climatic conditions ; and this limit
varies on the different soils.

The prevailing views with regard to the climatic factors
determining the successful limits of wheat cultivation are given
in the paper on the vegetation of the Leeds and Halifax district
(Smith and Moss, 1903 : 395 — 8). It is there stated, chiefly on
the authority of Buchan (1862), that wheat requires an average
summer temperature of at least 56° F. (13° C.) and a rainfall of
not more than about 33 inches (84 cm.). Judging by the
present distribution of wheat cultivation in Somerset and in
the present district, it would appear that whilst the above
figures are approximately correct as regards temperature, the
rainfall figures are too low by about ten inches (25 cm.) ; for
wheat regularly ripens in Somerset (see Moss, 1907 a or 6) and
in the Peak District, where the mean annual rainfall is over
40 inches (102 cm.).

Previous British vegetation maps have indicated the culti-
vated land by various tints of yellow, irrespective of the
proportion of arable land to permanent pasture. On future
maps, it is proposed to make some distinction between cultivated
land with a high proportion of permanent pasture, as in the
Peak District, and cultivated land with a low proportion of
permanent pasture, as in East Anglia; and the maps which
accompany the present volume are coloured on this plan.

It has previously been pointed out (Smith and Moss, 1903 :
399; Moss, 1907 a: 61) that the limit of wheat cultivation
corresponds roughly with the limits of a number of weeds and
aquatic plants. The following is a list of weeds which have
been noted in the arable fields of the district ; but it should
be borne in mind that, as there is but little typical wheat land
in the Peak District, the weeds of the wheat zone are, with
regard to the district as a whole, either very local or very
rare : —

VIII]

CULTIVATED LAND: CULTURE ASSOCIATIONS

207

Wheat and

Wheat zone

no-Wheat

zone

Equisetum arvense

Urtica dioica

U. urens

—

Rumex Acetosa

R. Acetosella

R. obtusifolius

Polygonum Convolvulus

—

P. aviculare (agg.)

P. rurivagum

—

P. Persicaria

P. lapathifolium

—

Cheuopodium album

—

Atriplex patula

var. angustissima

Silene Cucubalus

—

Lychnis alba

—

L. Githago

—

Stellaria media

Arenaria serpyllifolia

—

Spergula arvensis

Ranunculus arvensis

—

Papaver Rhoeas

r to o

—

P. dubium

—

Fumaria officinalis

—

F. pallidiflora

—

Cardamine hirsuta

—

Brassica nigra

—

B. arvensis

B. alba

—

Capsella Bursa-pastoris

Raphanus Raphanistrum

—

Alchemilla arvensis

—

Melilotus spp.

—

Trifolium spp.

Geranium molle

—

G. pusillum

—

G. dissectum

—

Euphorbia Peplus

E. Helioscopia

E. exigua

—

Viola arvensis (agg.)

— '

V. tricolor (agg.)

—

o, la

Scandix Pecten-Veneris

—

Aethusa Cynapium

—

Heracleum Sphondylium

Convolvulus arvensis

Lithospermum arvense

—

Mentha arvensis

—

208

VEGETATION OF THE PEAK DISTRICT

[CH.

Wheat and

Wheat zone

no-Wheat

zone

Stachys arvensis

Galeopsis angustifolia

—

G. versicolor

—

G. Tetrahit

Lamium purpureum

—

Veronica polita

—

V. agrestis

—

V. persica

—

V. arvensis

—

V. hederaefolia

—

Plantago major

P. lanceolata

Galium Aparine

Sherardia arvensis

—

Valerianella dentata

—

V. olitoria

—

Scabiosa arvensis

—

Bellis perennis

Gnaphalium uliginosum

Achillaea Ptarmica

A. Millefolium

Anthemis Cotula

—

A. arvensis

—

Matricaria inodora

M. Chamomilla

—

Tussilago Farfara

Senecio vulgaris

Cnicus arvensis

C. lanceolatus

Centaurea Cyanus

—

Lapsana communis

—

Taraxacum officinale

Sonchus oleraceus

S. asper

S. arvensis

—

Holcus lanatus

Poa annua

Bromus secalinus

—

B. racemosus

—

Lolium perenne (agg.)

Triticum repens

Juncus bufonius

VIII] CULTIVATED LAND : CULTURE ASSOCIATIONS 209

PLANTATIONS

The natural and semi-natural woods of the district have
been described in a previous chapter. It remains to mention
the plantations. The latter term is here used to denote purely
artificial associations of trees whose ground flora does not com-
prise shade-loving species.

In this district, plantations occur usually on the site of
former grassland, less frequently on a moorland site, and
scarcely ever on former arable land.

The trees most commonly planted are the Scots pine (*Pinus
sylvestris), the larch (* Larix decidua = * L. europaea), and the
beech (*Fagus sylvatica). Other trees which are locally abundant
in the plantations are the black or Austrian pine (*P. nigricans
— *P. austriaca), the spruce fir or Norway spruce (* Picea ex-
celsa), the oak (* Quercus Robur = * Q. pedunculata), and the
sycamore (*Acer Pseudoplatanus).

On the vegetation maps, the plantations which consist chiefly
of coniferous trees are distinguished from those which consist
chiefly of dicotyledonous trees by means of special colours ; and
the most abundant trees are indicated by letters, thus : *Pinus
sylvestris (p), * Larix decidua (=* L. europaea) (L), * Fagus
sylvatica (F), mixed conifers (C), mixed dicotyledonous trees (D),
or mixed coniferous and dicotyledonous trees (M). In the case
of plantations consisting of an approximately equal mixture of
deciduous and coniferous species, the fact is indicated on the
maps by stippling.

The pine plantations are more numerous on the non-cal-
careous than on the calcareous soils : larch and beech plantations
occur indifferently on either soil. In damp situations, the larch
is commonly attacked by canker (Dasyscypha calycina = Peziza
Wilkommii). The beech grows well in the district, more
especially perhaps on the limestones; but nowhere on the
Pennines does the tree appear to rejuvenate from self-sown
seed. Henry (1907 : 100) states that the beech is native in
this district ; but that is not the usual view. The place-name
Buxton which Henry infers means " beechtown," is capable of a
very different derivation. Lees (1888) says that the beech is
" possibly native on the Permian " or Magnesian Limestone of

M. 14

210 VEGETATION OF THE PEAK DISTRICT [CH.

Yorkshire. It is curious therefore that Lin ton (1903) should
not record the tree from a single station on the Derbyshire
continuation of the Permian Limestone of Yorkshire, although
one would think it must certainly occur here. Although the
matter is a difficult one to settle, the balance of evidence seems
to be against the view that the beech is native in Britain so far
north as Derbyshire. The tree, however, is indigenous in the
south of England, where it forms beech woods (see Moss, Rankin,
and Tansley, 1910), especially on the escarpments of the Chalk
and on the Greensand.

Many of the plantations are small ; and of these only those
in sheltered situations are successful. Small plantations in
exposed situations are often ruined by the severe and cold
winds of the hills ; and derelict plantations are far too common
on the Pennines (see figure 35).

On the other hand, the larger plantations are, on the whole,
in a prosperous condition, especially those in the valley of the
Derwent, e.g., the large one north-west of Strines reservoir, and
in the Goyt valley, e.g., the still larger one to the south-west of
Taxal. The one near Taxal is said to be the most extensive
plantation in Cheshire, and to occupy not less than a thousand
acres. It was begun about the year 1796 — 8 (see Holland,
1808: 10). The southern portion of this plantation is composed
almost wholly of beech (Fagus sylvaticd) planted on soil con-
taining sour humus. At the present time, the chief ground
species under the beeches is Deschampsia fle&uosa, but all the
commoner plants of the natural heath pasture occur. There
are very few other trees or shrubs ; but the beeches are vigorous
and healthy. This portion of the plantation is wholly below
1250 feet (379 m.).

The more elevated portion of the plantation is composed
principally of mixed conifers ; and, whilst a large proportion of
it is flourishing, some other portions (see figure 35) have been
completely ruined. These degenerate parts are situated either
in extremely exposed positions at high altitudes or on wet
moorland peat, both situations being highly unsuitable for tree
planting.

The following is a list of plants compiled on the site of a
portion of this decrepit plantation where the soil is wet, sour,
peaty, and badly aerated : —

Copyrigli t

Figure 35.

W. B. Crump

Derelict Plantation.

Larches (Larix decidua), Beeches (Fagus sylvatica), etc., on wet,
acidic peat. Ground vegetation of Heather (Calluna vulgaris),
cross-leaved Heath (Erica Tetralix), purple Moor-grass (Molinia
caerulea), Mat-grass (Nardus stricta), etc. Altitude 1600 feet
(488 m.). ,

VIII] CULTIVATED LAND: CULTURE ASSOCIATIONS 211

Sub-dominant

Erica Tetralix Calluna vulgaris

Molinia caerulea Eriophorum vaginatum

Abundant
Nardus stricta Deschampsia flexuosa

Locally abundant

Empetrum nigrum Vaccinium Myrtillus

Juncus squarrosus

Occasional
Potentilla erecta Galium saxatile

This list was taken at an altitude of about 1500 feet (457 m.);
and the plantation extends, or rather its remains extend, up to
1700 feet (518 m.). At altitudes higher than about 1550 feet
(472 m.), however, the plantations of the district are, generally
speaking, failures.

AFFORESTATION.

The question of the afforestation of waste lands in Britain
has in recent years occupied the attention of the public ; and
this attention has recently been stimulated by the publication
of a Government report.

As the present district comprises a large proportion of waste
or uncultivated land, and as it contains numerous plantations,
some successful and others unsuccessful, on parts of this waste
land, a few remarks on the general subject are here given.

Much of the waste land of the district is utterly unfitted
for immediate afforestation. This, in fact, applies to all peaty
moorland which is dominated by such plants as the cotjfcon-
grasses (Eriophorum vaginatum or E. angustifolium), Scirpus
caespitosus, heather (Calluna vulgaris), bilberry (Vaccinium
Myrtillus), crowberry (Empetrum nigrum), and purple moor-
grass (Molinia caerulea).

Before these sour and peaty places can be rendered fit for
afforestation, a great deal of preliminary work is necessary ;

14-2

212 VEGETATION OF THE PEAK DISTRICT [CH.

and, until the peat, which should first be removed, can be
profitably utilized in some way, the cost of the initial labour
on such soils would be such as to render any plantations un-
profitable from a financial point of view.

On the other hand, almost all the land which consists of
calcareous grassland, and also much of the siliceous grassland
dominated by the mat-grass (Nardus stricta), is fit, with a very
small amount of preparatory labour, to be immediately put
down to timber ; and, if proper precautions be taken, there is
no reason whatever why such plantations should not prove to
be undertakings of a financially profitable nature.

However, the numerous derelict plantations on the Pennines,
even on the grasslands, prove conclusively that reasonable pre-
cautions have frequently not been taken in the past ; and this
also applies not only to plantations laid down by private land-
owners but also to some recent attempts at afforestation on
the part of municipal corporations. It is frequently overlooked
that afforestation of uncultivated uplands is a very different
matter from the laying down of plantations in lowland localities
with a more genial climate ; and this aspect of the case is one
which does not appear to have been scientifically investigated by
English foresters. Again, many of the unsuccessful plantations
are of small size ; and small plantations on exposed uplands
cannot be expected to prosper. In a large plantation, the trees
within the plantation receive shelter from those at the margin ;
but a small plantation is quickly devastated from end to end.
Thirdly, the particular species of tree which is likely to flourish
on the chosen site is frequently not sufficiently considered,
although this would appear to be a matter of prime importance.
One frequently finds in the decadent plantations at least a dozen
species of trees and shrubs, some of which have never had any
reasonable chance of reaching maturity; and it would appear
that they have been obtained in an absurdly haphazard manner,
from some lowland nurseryman. Other important precautions
are often neglected ; but enough has been said to indicate that,
even on the more favourable sites, the afforestation of British
uplands is a matter which must be undertaken in a more
scientific spirit than has hitherto been the case if it has to
have any reasonable probability of success.

Figure 36.
Reservoir among the moors.

ir. n. Cni)iij>

VIII] CULTIVATED LAND: CULTURE ASSOCIATIONS 213

UTILIZATION OF THE PEAT-MOORS

It has been stated elsewhere (Moss, 1904) that the Pennine
peat-moors represent a valuable English asset which is turned
to little account. Grouse (Lagopus scoticus) are driven and
shot over them, it is true ; but considering the enormous rents
paid by tenants for good grouse moors, it is surprising that
more attention is not paid to the better cultivation of the
heather and the bilberry, as these plants are much better
adapted to the habits of the grouse than the cotton-grasses.
By suitable encouragement, the former plants could be made
to occupy much of the land now occupied by the latter.

Of late years, town and city corporations have utilized the
peat-moors as gathering grounds for reservoirs (see figure 36) ;
and thus an efficient water supply has been procured for the
ever-growing manufacturing towns and villages which flank the
Pennines.

Whilst the moors themselves are uninhabited, and have
been so throughout the historic period, there is, as has often
been shown (see Moss, 1904), abundant evidence to prove that
neolithic man tenanted the sites of the present moorlands before
the accumulation of the peat. The inhabitants of the moor-
edges, up to a comparatively few years ago, possessed turf-cutting
rights ; but these, in nearly all cases, seem to have been lost.
This is remarkable, as there is fuel enough in the Pennine peat
to last the hill -side population for a thousand years. In addition
to the value of the peat as fuel, the various products which
might be manufactured from the peat could be made to furnish
a satisfactory revenue, as is proved by the experience in certain
foreign countries, such as Sweden. Finally, if the peat were
gradually removed and utilized, the surface thus laid bare
would, in many places, become fit for successful reclamation
or afforestation.

APPENDIX I

SUMMARY AND RELATIONS OF THE PLANT
COMMUNITIES OF THE PEAK DISTRICT

1. THE PLANT FORMATION OF CALCAREOUS
SOILS (CALCARION)

Group of Associations

Chief Associations

Subordinate Associations

Ash wood (Fraxinetum
excelsioris)

Calcareous grassland
(Festucetum ovinae)

Vegetation of screes and
rocks

Limestone swamps

Progressive scrub
Retrogressive scrub

Calcareous heath

grassland
Calcareous heath
Vegetation of swamps
Vegetation of " rakes "
Vegetation of screes
Vegetation of rocks

Ash Wood

/ ^

Retrogressive scrub Progressive scrub

X S

Calcareous Pasture

Calcareous Heath Pasture

Calcareous Heath

c
04

APPENDIX I

215

2 THE PLANT FORMATION OF SILICEOUS SOILS (SILICION)

Group of Associations

Chief Associations Subordinate Associations

Woods

Scrub
Grassland

Siliceous swamps

Birch wood (Betuletum

tomentosae) '
Oak wood (Quercetum

sessiliflorae)

Siliceous grassland
(Nardetum strictae)

Molinia grassland (Mo-
linietum caeruleae)

Progressive scrub
Retrogressive scrub

Siliceous grassland
with much
(a) UlexGallii
(6) Pteris aquilina

(d) Deschampsia

flexuosa

(e) Juncus effusus

or J. effusus
forma com-
pactus
(/) Calluna vulgaris

Vegetation of swamps

216

VEGETATION OF THE PEAK DISTRICT

3. THE PLANT FORMATION OF THE ACIDIC
PEATY SOILS (OXODION)

Formation

Moor

Chief Associations

Molinia moor (Molinietum

caeruleae)
Heather moor (Callunetum

vulgaris)

Bilberry moor ( Vaccinietum

myrtilli)
Cotton-grass moor (Erio-

phoretum vaginati)

Subordinate Associations

Heather moor with much

(a) Vaccinium Myrtillus

(b) Eriophorum vagina-

turn

Cotton-grass moor with
much Eriophorum angus-
tifolium

Retrogressive moor with
much

(a) Vaccinium Myrtillus
(6) Empetrum nigrum

(d) Bare peat

APPENDIX I

217

4. THE RELATIONSHIPS OF THE OXODION AND
THE SILICION

[Sub-Alpine Grassland]

Bilberry Moor

} SILICION '

Bare Peat

Heather and

Retrogressive Moor

Cotton-grass Moor

Cotton-grass and Heather Moor
/*

Heather Moor-

Molinia Grassland or Moor

Bilberry Moor

Nardua Grassland
with much Heather

Nardus Grassland

Oak and Birch Scrub
Oak or Birch wood

> OXODION

V SILICION

5. THE PLANT FORMATION OF FRESH WATERS

1. Associations of rapidly flowing non-calcareous waters.

2. Associations of rapidly flowing calcareous waters.

3. Associations of moving waters.

4. Associations of stagnant waters.

5. Associations of reed swamps.

APPENDIX II

SUMMARY OF BRITISH PLANT FORMATIONS
AND ASSOCIATIONS

I. The Plant Formation of Fresh Waters.

A. The Sub-formation of Foul Waters.

B. The Sub-formation of nearly Stagnant Waters (i.e., with no

flood-currents).

1. Associations of Submerged Plants (e.g., Chareta).

2. Associations of Plants with Floating Leaves (e.g., Lemneta).

2 3. Associations of Reed Swamps (e.g., Phragmitidetum vulgaris).

C. The Sub-formation of Slowly-moving Water (with periodical

flood-currents and rich in dissolved mineral salts).
21. Associations of Submerged Plants (e.g., Ranunculetum

circinati).
2 2. Associations of Reed Swamps (e.g., Qlycerietum aquaticae).

D. The Sub-formation of lake-margins, with well-aerated waters.

E. The Sub-formation of Quickly-flowing Streams of hill and

mountain slopes.

1 1. Associations of Streams with Calcareous Waters.

1 2. Associations of Streams with Non-calcareous Waters.

F. The Sub-formation of Stagnant and Acidic Waters.

II. The Plant Formation of Salt and Brackish Waters.

1. Associations of Sea-weeds (e.g., Laminarietum digitatae).

2. Associations of submerged Marine Flowering Plants (e.g.,

Zosteretum marinae).

3. Associations of Marine and Tidal Reed Swamps (e.g.,

Spartineta).

4. Associations of Brackish Waters (e.g., Ranunculetum bau-

dotii).

5. Associations of Brackish Reed Swamps (e.g., Scirpetum

maritimi).

1 Well represented in the Peak District.

* Fairly well represented in the Peak District.

APPENDIX II 219

III. The Plant Formation of Salt (NaCl) Soils.

1. Associations of open Salt Marshes (Salicornietum europaeae ;

S. ramosissimae).

2. Associations of intermediate or mixed Salt Marshes (e.g.,

Staticetum maritimae).

3. Association of salt marsh grassland (e.g., Glycerietum mari-

timae).

4. Associations of retrogressive Salt Marshes (e.g., Atripli-

cetuin portulacoidis).

5. Associations of Spray-washed Rocks (e.g., Crithmetum

maritimi).

6. Associations of Strand Plants (e.g., Atripliceta; Salsoletum

kali). Transitional to dunes.

7. Associations of Maritime-fen Grassland. Transitional to fens.

IV. The Plant Formation of Sand Dunes and Shingle Banks.

1. Associations of Embryonic Dunes (e.g., Agropyretum juncei).

2. Associations of Shifting Dunes (e.g., Ammophiletum

arenariae).

3. Associations of Fixed Dunes (e.g., Festuceta).

4. Associations of Retrogressive Dunes.

5. Associations of Shingle Banks.

V. The Plant Formation of dry Sandy and Gravelly Soils.

1. Associations of dry woodlands.

a. Sub-association of Fagus sylvatica. Transitional to IX.

b. Sub-association of Qiiercits spp.

c. Sub-association of Betula spp.

d. Sub-association of Pinus sylvestris.

e. Mixed woods.

2. Associations of Scrub.

3. Associations of Sandy Grassland.

VI. The Plant Formation of Heaths.

1. Association of Calluna vulgaru.

b. Sub-association of Erica cinerea.

2. Associations of Heath Moors. Transitional to XII.

VII. The Plant Formation of the older Siliceous Soils.

21. Association of Birch Woods (Betuletum pubescentis).

1 2. Association of Oak Woods (Quercetum sessiliflorae).

13. Associations of Scrub.

J4. Associations of Siliceous Grassland (e.g., Nardetum strictae ;

Molinietum caeruleae). Molinieta are transitional to

moors.
J5. Associations of Swamps (e.g., Juncetum effusi). Transitional

toX.

220 VEGETATION OF THE PEAK DISTRICT

VIII. The Plant Formation of Clayey Soils.

1. Association of damp Oak Woods (e.g., Quercetum roboris).

b. Sub-association of damp Oak-Hornbeam Woods.

2. Associations of Scrub.

3. Associations of Neutral Grassland.

4. Associations of Swamps. Transitional to X.

IX. The Plant Formation of Calcareous Soils.

1. Association of Beech Woods on Chalk (Fagetum sylvaticae).

2. Association of Yew Woods on Chalk (Taxetum baccatae).
1 3. Association of Ash Woods (Fraxinetum excelsioris).

4. Association of Ash-Oak Woods on calcareous clays and marls.

1 5. Associations of Scrub.

1 6. Associations of Calcareous Grassland (e.g. , Festucetum ovinae)

1 7. Associations of Swamps. Transitional to X.

X. The Plant Formation of Marshy Soils (i.e., soils subject to periodical

inundations).

1. Associations of Marsh Woods (e.g., Alneta, Saliceta).

2. Associations of Marsh Scrub.

3. Associations of Marsh Grassland.

XI. The Plant Formation of Peaty Soils with alkaline Waters ( = the

Fen Formation).

1. Associations of Fens.

2. Associations of Fen Scrub.

3. Associations of Fen Woods.

4. Associations of Fen Grassland. Transitional to X.

XII. The Plant Formation of Peaty Soils with acidic Waters ( = the

Moor Formation).

1. Associations of Bog-mosses (Sphagneta).

2. Associations of Moor Scrub.

3. Associations of Moor Woods, e.g. (Pineta, Betuleta).

4. Association of Rhyncospora alba. Transitional to XL

5. Association of Eriophorum angustifolium.

6. Association of Scirpus caespitosus.

7. Retrogressive Associations with Rhacomitrium lanuginosum.

18. Association of Cotton-grass Moor (Eriophoretum vaginati).
*9. Retrogressive Associations with Vacdnium Myrtillus, Em-

petrum nig/rum, and Rubus Chamaemorus.

1 10. Association of Bilberry Moor (Vaccinietum myrtilli).

16. Sub-association of Vacdnium Vitis-idaea.

111. Association of Heather Moor (Callunetum vulgaris).
8 12. Association of Grass Moor. Transitional to VII.

XIII. The Plant Formation of Alpine Summits.

1. Associations of Calcareous rocks.

2. Associations of Non-calcareous rocks.

APPENDIX II 221

XIV. The Plant Formation of Cultivated Land.
1. Associations of the Alluvial" Zone.

a. Permanent Pasture.

b. Arable Land.

2 2. Associations of the Wheat Zone.
2 a. Permanent Pasture.
2 b. Arable Land.

c. Orchards.

d. Market Gardens.

1 3. Associations of the No- wheat Zone.
la. Permanent Pasture.
2 6. Arable Land.

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APPENDIX III 227

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INDEX

Acidic humus, 55, 56
Acidic soils, 37
Afforestation, 211
Alder, 49, 70

Alder societies in woods, 70
Alder-willow thickets, 58
Alkaline soils, 37
Alluvial fen, 105
Alluvium, River, 10
Altitude, Effect of, 174
Altitudinal limit of aquatic plants, 154,
156, 159

grassland, 103, 104

scrub, 88

trees, 38, 88

trees, past and present, 88

woodland, 44

wheat cultivation, 205
Aquatic associations, Marsh and, 144
Aquatic plants, Altitudinal limits of,

154, 156, 159
Arable land, 204
Ash (see also Willow), 52, 69

Cultivation of, 67

Germination of seeds of, 67

Mountain, 50
Ash Woods, Absence of oak from, 70

Damp places in the, 72

Dry places in the, 72

of Fraxinus excelsior, 65

Ground vegetation of the, 71

Herbaceous vegetation of the, 71

Trees and Shrubs of the, 69
Aspects of associations, Seasonal, 20
Associations, Aquatic and Marsh, 144

Chief, 21

Closed, 20, 21

Culture, 199

Facies of, 20

Grassland, 103

Intermediate, 20, 125

Mixed, 21

Moorland, 163

Open, 20

Passage, 125

Plant, 19

Progressive, 20

Pure, 21

Retrogressive, 21
of rocks and screes, 134
Scrub, 88

Seasonal aspects of, 20
Siliceous and calcareous soils, 133
Siliceous soils, 133, 215
Stable, 20
Subordinate, 21
Succession of, 20, 94
Transitional, 183, 186
Unstable, 20
Woodland, 38

Atmosphere, Humidity of the, 34
Temperature of the upper, 28
Upper, 27

Bare peat, 191

Barley, Cultivation of, 205

Basalt, 9

Basic soils, 37

Beech, 49, 68, 70

Germination of seeds of, 49
Betnla (see Birch)
Betulftum pubescentis, 61
Bilberry, 52

Bilberry moors, 166, 182
Birch, Common, 48, 70
Birch and Oak woods, 60
Birch forest, Primitive, 63
Birch societies in oak woods, 49
Birch, White, 49, 70
Birch woods of Betula pubescens, 59
Birch woods, Ground vegetation of, 62

Scots pine in the ancient, 48, 64
Birdcherry, 51
Blackberry, 51
Blackthorn, 51
Bleaklow Hill, 104, 193
Bog moss (Sphagnum), 166, 184
Bogs (see Moors)
Bog xerophytes, 145, 174
Boulder clay, 9
Bracken, Requirements of, 108
Bramble, 51
Brier, 51

British moors, 166, 220
British plant formations and associa-
tions, Summary of, 218

15—3

230

INDEX

British woodlands, 39

Broom, 51

Bryophytes of Calcareous waters, 157

limestone rocks, 135

moors, 172

non-calcareous waters, 157

sandstone rocks, 141

streams, 157

woods, 86, 87
Buried timber in the peat, 90

Calcareous grassland, 105, 116

grassland, Mixed, 121

heath, 122

heath, Pseudo-, 126

soils, 8, 12, 14

waters, 150
Calcarion, 214
Calluna (see heather)
Callunetum vulgaris, 176
« Carboniferous (or Mountain) Lime-
stone, 8, 12, 66

Changes in the moorland habitat, 175
Chasmochomophytes, 143
Chemical nature of the soil, 43
Cherry, 51
Chert, 9, 10, 12
Chestnut, 59
Chief associations, 21
Chomophytes, 143

Classification of grassland associations,
104

moorland associations, 166

scrub associations, 99

woodland associations, 40
Cliffs, Limestone, 134

Sandstone, 140, 182
Climatic formations, 21

scrub, 89

Closed plant associations, 20, 21
Clover, Cultivation of, 205
Coal measures, 7
Communities, Plant, 17, 19
Comparison of woodland species, 74, 79
Complimentary society, 73
Conifers, 47, 69

Construction of Vegetation Maps, 18
Cotton-grass moors, 166, 167, 183

Species of, 186
Cowberry,. 52
Crabapple, 50
Cultivated land, 199

Nature of, 199

Origin of, 199
Cultivation of Clover, 205

Oats, 205

Bye, 205

Wheat, 206
Culture associations, 199

Damp places in the ash woods, 72

oak woods, 54
Degeneration of scrub to grassland, 94

woodland, 91, 94
Deposits, Glacial, 9
Depth of soil, 43, 173
Derelict plantations, 210
Description of the Peak District,

General, 1
Dewberry, 51
Direction of the wind, 30
Distribution of aquatic and marsh
associations, 144

grassland, 103

moorland, 163

scrub, 93

woodland, 38
Dry places in ash woods, 72

oak woods, 55
Dysgeogynous soils, 73

Ecological Factors, 24, 41, 53, 58,
137, 140, 173

and Phytogeographical Nomen-
clature, 19, 61, 95
Edge, Bilberry, 182
Elder, 52
Elm, 50, 69

Germination of seeds of, 50
Eriophoretum vaginati, 183
Eriophorum (See Cotton-grass)
Exochomophytes, 143
Exposure, Effect of, 174
Extent of plant formations, 21

Facies of associations, 20

grassland, 108

Nardetum strictae, 108
Factors, Ecological, 24, 41, 53, 58,

137, 140, 173
Federation, Plant, 110
Fen formation, 168

grassland, Alluvial or, 105

peat, 168, 170
Fens, Moors and, 170
" Fettwiesen," 121
Firing of the moors, 178
"Flachmoor," 168
Flora and Vegetation, 16
Floristic maps, Vegetation and, 22
Forest (see also woods and wood-
lands), 95
Fog, 26

Formations and Associations of the
Peak District, Summary and
relations of, 214

Climatic, 21

Extent of plant, 21

Fen, 168

Life history of plant, 21

INDEX

231

Plant, 19

Species of the moor, 197
Fraxinus (see Ash)
Fresh waters, Plant formation of,

217, 218
Furze, 61

Dwarf, 51

General description of the Peak

District, 1

Geological Strata of the District, 12
Geology of the Peak District, 5
Germination of seeds, Difficulties of,

92, 93
of ash, 67
of beech, 49
of elm, 50

of heather, 179
Glacial deposits, 9
Glaciation of the Peak District, 9
Gorse, 51
Grassland, Alluvial, 105

Artificial (see Permanent Pasture)

Associations of, 103

Altitudinal limit of, 103, 104

Calcareous, 105, 116

Climatic, 89

Distribution of, 103

Facies of, 108

Fen, 105

Mixed Calcareous, 121

Mixed Siliceous, 112

Molinia, 114

Nardus, 106

Neutral, 105

of the Sandstones and Shales, 106

Siliceous, 104, 105, 106

Species of the, 127

Species of the Mixed Siliceous, 112

Sub-Alpine, 104, 105, 193

Transitional Calcareous, 122

Transitional Siliceous, 186

Types of, 104
Gravels, Eiver, 13
Grazing, 105
Ground Vegetation of ash woods, 71

birch woods, 62

oak woods, 53

woods and its relation to de-
generate scrub, 97
Group of associations, 22
Grouse, 213
Guelder rose, 52

Habitat, 19

of the moorland, changes in the,

93, 175

Hawthorn, 50, 69
Hazel, 48, 70
Heath, 95, 179

Heather, 52

Germination of seeds of, 179

moor, 166, 176

moor, Species of, 179, 180, 197

on limestone, Occurrence of, 122,

125

Heaths, 219
Heath, Calcareous, 122
Heath, Pseudo-calcareous, 126
Hedgerows, 200
Herbaceous vegetation of ash woods, 71

oak woods, 53
Highest elevations of the Peak District,

1, 2

"Hochmoor," 168

Holly, 51

Honeysuckle, 52

Humidity of the atmosphere, 34

Humus, 8

Acidic, 55, 56

Mild, 54

Igneous Rocks, 9
Influence of Shade, 58
Injurious effects of Smoke, 26
Intermediate associations, 20, 125
Ivy, 52

Junceta, 148

Juncetnm effusi, 148

Juncus facies of Siliceous grassland,

108

swamps, 149
Juniper, 69

Larch, 68, 70

Lianes, 52

Life history of plant formations, 21

Limestone, 65

Carboniferous (or mountain), 8,
12, 66

cliffs, 134

Grassland of the, 116

heath, 122

Occurrence of heather on, 122, 125

rocks, Bryophytes, 135

rocks, 134

screes, 137

scrub, 99

slopes, Semi -natural woods and
plantations on the, 68 ,

Swamps (or marshes) of the, 152
Ling, 52
Lithophytes, 142, 143

Maple, 51

Maps, Floristic and Vegetation, 22
Marsh and Aquatic associations, 144
Marshes of the limestone, 152
sandstones and shales, 146

232

INDEX

Marshy places in the ash woods, 72

oak woods, 53
Meso-pteridetum, 57
Mild humus, 54
Millstone grit, 7, 13
Mineral Salts, 7, 8

to flora and vegetation, Relation

of, 161
Mixed calcareous grassland, 121

plant associations, 21

siliceous grassland, 112
Molinia grassland, 114, 215, 216, 219
Molinietumcaeruleae, 114,215, 216,219
Moor formation, Species of the, 197
Moorland associations, 163

Classification of, 166
Moorland, Changes in the habitat of
the, 93, 175

plants, Boots of, 174
Moors and fens, 170

Bilberry, 166, 182

British, 166, 220

Bryophytes of the, 172

Cotton-grass, 166, 167, 183

Firing of the, 178

Heather, 166, 176

Moss, 183

Origin of the, 94, 98, 181, 186, 194

Rainfall of the, 175

Reservoirs on the, 213

Retrogressive, 166, 188

Rbacomitrium, 167

Scirpus, 167

Species of the heather, 179, 180, 197

Sphagnum, 166

Transitional, 166

Mountain or Carboniferous limestone,
8, 12, 66

Nardetum strictae, 108

fades of, 108
Nardus grassland, 106
Nature of cultivated land, 199
Neutral grassland, 105
Nomenclature, Ecological and Phyto-

geographical, 19, 61
Non-calcareous or siliceous soils, 8
12, 14

waters, 146

Oak and birch woods, 60
Pedunculate, 47
Sessile-fruited, 47

Oaks from the Ash woods, Absence
of, 70

Oak woods, Damp places in the, 54
Dry places in the, 55
Ground vegetation of, 53
Herbaceous vegetation of, 53
of Quercus Robur, 44

Quercus sessiliflora, 46, 61, 215

Transitional, 45

Trees and shrubs of the, 47

Variation of Vegetation in, 53
Oats, Cultivation of, 205
Open plant associations, 20
Origin of the cultivated land, 199

moors, 94, 98, 181, 186, 194

peat, 8

scrub, 91, 94, 98
Oxodion, 167, 216, 217

Passage associations, 125

Past and present upper altitudinal

limit of trees, 88
Pasture, Permanent, 105, 202
Peak District, General Description of
the, 1

Geology of the, 5
Peak of Derbyshire, 1, 189

Derbyshire, Vegetation of the sum-
mit of the, 189
Peat and Geological Maps, 12

Bare, 191

Buried timber in, 90

Depth of, 173

Fen, 168, 170

moors, 168, 170

moors, Altitude of, 174

Origin of, 8

Pine in the, 47, 89, 91

Sand and Humus of, 173

Utilization of the, 213
Pendleside (or Yoredale) rocks, 7, 13
Permanent pasture, 105, 202
Petrophytes, 143

Phytogeographical nomenclature, Eco-
logical and, 19, 61, 95
Pine, 70

in the ancient birch woods, Scots,
48, 64

in the peat, 47, 89, 91
Plant associations, 19

communities, 17, 19

federation, 110

formations, 19

extent of, 21

life history of, 21

societies, 19
Plantations, 209

Derelict, 210
Poplars, 48, 70
Primitive birch forest, 63
Progressive associations, 20

and retrogressive scrub, 97, 98
Pseudo-calcareous heaths, 126
Pure plant associations, 21

Quercetum roboris, 44, 220
sessiliflorae, 61, 46, 219

INDEX

233

Quercus (see Oak)

Bainfall, 24

of the moors, 175
Rakes, 12, 119
Raspberry, 50
Reclamation of uncultivated land,

201

Reed swamps, 154
Refuse heaps of lead mines and gravel

mines, 12, 119
Reservoirs on the moors, 213
Retrogressive associations, 21

moors, 166, 188

scrub, 97, 98

Rhacomitrium moors, 167
River alluvium, 10

gravels, 13
Rocks and screes, 134, 137

and soils, 5

Limestone, 134

Sandstone, 140

Rocky Knolls in ash woods, 74
Roots, 205

of moorland plants, 174
Rose, Wild, 51
Rowan, 50

Ruderal marsh species, 153
Rye, Cultivation of, 205

Salts, Mineral, 7, 8

Sand and Humus of peat, 173

Sandstone cliffs, 140, 182

rocks and screes, 140
Sandstones and shales, 8, 13

Grassland of the, 106

Swamps or marshes of the, 146

Scrub of the, 99

Woods of the, 46

Sandstone rocks, Bryophytes of, 141
Sandy soils, 9, 13, 44, 45
Scenery, Types of, 3
Scirpus moors, 167
Screes, Limestone, 137

Rocks and, 134

Sandstone, 140
Scrub, Altitudinal limit of, 88

Associations, 88

Climatic, 89

Distribution of, 93

Edaphic, 97

in other districts, 96

Kinetic, 97

Limestone, 97

to grassland, Degeneration of, 94

of sandstone and shales, 99

Origin of, 91, 94, 98

Progressive, 97, 98

Retrogressive, 97, 98

Static, 97

.Types of, 95, 97

Seasonal aspects of associations, 20
Seeds, Difficulties of germination of,
92, 93

of Ash, Germination of, 67

beech, Germination of, 49

elm, Germination of, 50

heather, Germination of, 179
Shade on the ground vegetation, In-
fluence of, 58
Shale, 8, 13
Shrubs of ash woods, Trees and, 69

oak woods, Trees and, 47
Siliceous grassland, 104, 105, 106

and moorland, Relationships of, 187
Siliceous soils, 8

Associations of, 133, 215

Relationships of the plant forma-
tions of, 196
Silicion, 217
Sloe, 51
Smoke, 25

Injurious effects of, 26
Society, Complimentary, 73
Societies, Plant, 19
Soil, Acidic, 37

Alkaline, 37

Basic, 37

Chemical nature of the, 43

Depth of the, 43, 173
Soils and their characteristic plants, 13

associations of siliceous and cal-
careous, 133

and Vegetation, 12, 13

Dysgeogynous, 73

non-calcareous or siliceous, 8, 12,
14

of the district, 12

of the sandstones and shales, 43

Rocks and, 5
Species of acidic peaty soils, 14

alder-willow thickets, 59

arable land, 207

ash woods, 79

bilberry moors, 182, 197

birch woods, 62

calcareous soils, 14

calcareous grassland, 127

calcareous waters, 157, 160

cotton grass moor, 186, 197

Heather moors, 179, 180, 197

Juncus swamps, 149

mixed siliceous grassland, 112

moor formation, 197

non-calcareous waters, 157, 160

oak woods of Quercus sessiliflora,

79
Species of permanent pasture, 202, 203

reed swamps, 155

scrub on limestone, 99

234

INDEX

scrub on sandstone, 99
scrub on shale, 99
siliceous grassland, 127
siliceous soils, 14
sub-Alpine grassland, 193
swamps on limestone, 152
transitional moors, 187
transitional moorland and grass-
land, 181

Sphagnum (see also Bog Moss), 184
Moors, 166
in peat, 184

Stable plant associations, 20
Strata of the District, Geological, 12
Streams, Bryophytes of, 157

Vegetation of quickly flowing, 155
Structure of moorland plants, 145,

174

Sub-alpine grassland, 104, 105, 193
Sub-associations of plants, 19
Subformations of plants, 19
Subordinate plant associations, 21
Succession, 20, 94, 193
Succession of forest to scrub, 91, 94
grassland to heath, 122, 214
grassland to moorland, 94, 114,

115, 181, 217
moorland to grassland, 186, 193,

217
moorland plant associations, 188,

217
scrub to grassland, 94, 115, 133,

217

woodland to grassland, 114, 217
woodland to scrub, 94, 97, 115,

133, 214, 217
Summary of British plant formations

and associations, 218
Summary and relations of plant com-
munities of the Peak District,
214

Swamp xerophytes, 145, 174
Swamps, Juncus, 149
Swamps or marshes of the limestone,

152

sandstones and shales, 146
Swamps, Eeed, 154
Sycamore, 51, 68

Temperature, 26, 28

Thickets, Alder-willow, 58

Toadstone, 9

Transitional associations, 183, 186

calcareous grassland, 122

grassland and moorland, 181, 186

moors, 166, 187

moorland associations, 183, 187

siliceous grassland, 186

woods of Quercus Robur and
Q. sessiliflora, 45

Trees, altitudinal limit of, 38, 88
Trees and shrubs of ash woods, 69

oak woods, 47
Tufa, 13
Turnips, 205
Types of grassland, 104

scenery, 3

" Ubergangsmoor," 170

Universal names in phytogeography,

19, 61, 95

Unstable associations, 20
Uncultivated land, Beolamation of,

201

Upper atmosphere, 27
Utilization of the peat moors, 213
waste land, 23

Vaccinietum myrtilli, 182, 216
Vaccinium edges, 182

Myrtillus (see Bilberry)

ridges, 182

Value of Vegetation Maps, 22
Variation of vegetation in oak woods,

53
Vegetation and soils, 12, 13

Flora and, 16
Vegetation maps, 18

and floristic maps, 22

Construction of, 18

Value of, 22
Vegetation units, 17
Velocity of the wind, 32
Vernacular names in plant geography,

95
Volcanic rocks, 9, 12

Water in the peat, 173
Water of the moors, 173
Waters, Acidic, 37, 39

Alkaline, 37, 39

Basic, 37, 39

Calcareous, 150

Non-calcareous, 146

Plant formation of fresh, 217,

218

Weeds of arable land, 207
Wheat cultivation, Altitudinal limits

of, 205

Willows, 48, 70
Wind, Velocity of the, 32
Woodland associations of Great Britain ,
39

of the Southern Pennines, 40
Woodland, Altitudinal limit of, 44

Degeneration of, 91, 94

Distribution of, 38
Woodland plants, Comparison of, 74,

79
Woodland species, 79

INDEX 235

Woods and plantations on limestone on non-calcareous soils, 39

slopes, Semi-natural, 68 on very wet soils, 39

Woods, Ash, 65 of the Sandstones and Shales, 46

Birch and oak, 49, 60

Bryophytes of, 86, 87 Xero-Pteridetum, 56, 57
Distribution of the, 38

Ground vegetation of, 53, 62, 71, Yew, 69

97 Yoredale or Pendleside rocks, 7, 13
Oak (Quercus Robur), 47

Oak (Quercus sessiliflora), 47 Zonation of the moorland and grass-
on calcareous soils, 40 land associations, 194

CAMBRIDGE : PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS

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