Introduction to the plant-life of the Oxford district

BOTANICAL MEMOIRS. No. 13

UC-NRLF

B 14 3m

INTRODUCTION TO THE PLANT-LIFE OF THE
OXFORD DISTRICT

I. GENERAL REVIEW

By
A. H. CHURCH, M.A.

HUMPHREY MILFORD
OXFORD UNIVERSITY PRESS

LONDON EDINBURGH GLASGOW COPENHAGEN

NEW YORK TORONTO MELBOURNE CAPE TOWN

BOMBAY CALCUTTA MADRAS SHANGHAI

1022

Price Three Shillings and Sixpence net

BIOLOGY
RA

G

BOTANICAL MEMOIRS. No. 13

INTRODUCTION TO THE PLANT-LIFE OF THE
OXFORD DISTRICT

I. GENERAL REVIEW

By
A. H. CHURCH, M.A.

HUMPHREY MILFORD
OXFORD UNIVERSITY PRESS

LONDON EDINBURGH GLASGOW COPENHAGEN

NEW YORK TORONTO MELBOURNE CAPE TOWN

BOMBAY CALCUTTA MADRAS SHANGHAI

1922

BIOLOGY
LIBRARY

G

CONTENTS

PAGE

I. INTRODUCTION 3

II. PHYSICAL FEATURES 7

Climate, Geology, Surface-modelling . . . .10
The Modern River-System 24

III. PRIMARY WOODLAND AND ITS DERIVATIVES ... 28

IV. SUBORDINATE AND HERBACEOUS FLORA .... 33
V. THE HAND OF MAN 46

VI. ARTIFICIAL PLANT-FORMATIONS 53

Woodland and Copse 53

Hedgerows and Hedgebanks 59

Regressive Woodland 63

Grassland and the Evolution of Pasture . . . .65

Roadsides 73

Crops and Weeds of Arable Land 77

Small Holdings and Allotments 85

The Regression of Cultivated Land 91

VII. ALIENS AND ADVENTIVES 93

I.

INTRODUCTION TO THE PLANT-LIFE OF THE
OXFORD DISTRICT

ONCE free from streets and houses, considered as mere evidence of the
gregarious habits of a modern population with the quite natural obsession
that the world was specially designed for the welfare of the human race,
it is only necessary to take an unbiased view of the condition of the
surrounding country, to be inevitably inclined to the conclusion that, even
in this part of the world, where half the year is spent in a struggle with the
cold and storms of winter, Plant-life is enormously preponderant, and the
vegetation of the countryside is the primary phase of life to be considered
in dealing with all biological problems of the locality.

Trees or grass clothe the visible surface of the land, in close canopy or
as thick undergrowth ; animal life, beyond a few birds and the animals
maintained by man,1 is conspicuously inconspicuous. Towns appear but as
ant-heaps spaced far apart in the general green mantle of vegetation ; and
however much man may interfere with and attempt to dominate or even to
replace the indigenous flora, his attempts are of doubtful permanence.

In point of time modern towns have a history of little over one thousand
years ; 2 that of the flora, even of this country, may be measured possibly in
hundreds of thousands ; and a modern city, with its fortuitous collection of
human beings, may as readily dissolve again, and their rejectamenta be lost
and buried under returning vegetation. An enthusiastic entomologist has
claimed that the present age is pre-eminently that of insects ; a medical writer
might with equal acumen describe it as the age of bacteria. Omitting any
considerations as to the relative importance of extreme lines of biological
development, there can be no question that in all ages, as the base of the
pyramid of life on this world, the autotrophic plant is the dominant factor
for all time. That is to say, the living plant, on which we are still mainly
dependent for our supplies of food and energy, is dominant in aggregate
mass and volume of living material, as also in vitality and staying power,
however much we may try to ignore the fact, and endeavour to extirpate
the last persistent weed.

The flora of the British Islands, as a whole, is but the much deterio-
rated version of a European flora of the North Temperate zone; the latter
again consisting mainly of successive migrants or survivals from a more sub-
tropical environment, as vestiges of families, often represented by single
genera, or by the last enduring species pushed farthest north. Of the
British types of vegetation, that of the central plain of England is, again,
the most inferior, in variety of forms, as of biological constituents. The
local Oxford flora can show no heath-moors, alpine slopes, sand-dunes,
shingle beaches or estuarine swamps, which have so attracted ecologists in
other directions ; 3 it remains characteristically commonplace, sylvestral,
agrestal, paludal, with no special developments in any direction, and with

1 For statistics cf. Orr (1916), Agriculture in Oxfordshire. Approximately i sheep for i\ acres,
a cow or bullock for 7 acres, a pig to 20 acres, and a horse used in field-work to 40 acres.

With intensive cultivation a cow may be kept on an acre of pasture, representing the photo-
synthetic output of some 5 million plants.

2 The Oxford Millenary celebrated 1912.

3 Carey and Oliver (1908), Tidal Lands.
Tansley (1911), Types of British Vegetation.

A 2

5281U2

4 £ I : *: i\\Pfo$t~life °f Me Oxford District

little to attract the visitor from other more favoured districts. Yet it is this
very commonplace character which constitutes its greatest asset. With
attention no longer distracted by special factors or extreme conditions of
soil and water-supply, one may settle down to the examination of just what
constitutes the ordinary flora of the river-valleys of the central plain of
England, its limitations and its expression in common types which represent
the response to a fairly average condition of environmental factors.
Recognizing, again, the important fact that however commonplace such
a flora may be in the present locality and conditions, it is not so very
widely spread. The floras of other more emphasized biological districts are
equally commonplace to the natives of those regions, and the plants of an
English countryside may have a special scientific interest alike for the
inhabitants of Greenland's icy mountains or those of India's coral strand, as
conversely the English botanist is expected to be familiar with the ecology
of these distant lands.1 To a floating population of students3 the analysis
of the local flora may serve as a guide to the methods of attacking the
general problems of plant-life quite as well as that of any other. Though it
may be characterized as ' homely ' in its general features,2 it is nevertheless
essentially British and English in its more fundamental factors. In spite
of modern tendencies for admiring any country but one's own, it must be
remembered that for all those who in this country are still privileged to
trace an Anglo-Saxon origin, plant-life of this description has been intimately
associated with the life of the essentially English race for a period of some 50
generations (1,500 years). To our mediaeval ancestors the ecological factors
of the plant-life of such a countryside, with its woodland, pasture, arable
land and streams, were the primary factors of their own lives also ; as their
continued existence and material comforts depended solely on the special
plant-products of the land, whether in the form of timber,3 food-grains,
fodder, vegetables, fruit, and even medicines,4 to an extent that is difficult
to realize by a present town-bred population fed mainly from overseas ;
while 50 per cent, of the nation live in towns of 50,000 inhabitants or more,
and even in the smaller towns comparatively few are brought into direct
contact with the primary life of the district around them. While, again, in
the past, the common plant-lore of the countryside has been naturally
incorporated in older English literature, as typified by the Shakespearian
drama, books are written for a modern urban generation to explain the
' plant-allusions ' of Shakespeare,5 just as Bible-students require to be
primed with references to an equally unfamiliar flora of Palestine and the
ecological relations of the Syro-Arabian desert.

The present discussion is restricted to an account of the region more
immediately surrounding Oxford, within reasonable distance for investiga-

1 Troup (1921), Silviculture of Indian Trees.

Schimper (1903), Plant Geography, Eng. Trans., p. 688'; Holttum (1922), Journal of Ecology,
x, i, The Vegetation of West Greenland.

8 P. B. Shelley, Univ. Coll. 1810, l The Country near Oxford has no pretensions to peculiar
beauty, but it is quiet and pleasant and rural, and purely agricultural after the good old fashion.'

8 In early times the success of English armies was based on the equipment of archers with
a remarkable type of self-bow determined by the special properties of the wood of Taxns ; as in
later times the navy depended on the quality of English-grown Quercus. Oak-timber also gave
efficiency to building construction.

4 British Botany begins officially with the essentially medical works of Turner, 1551.

6 Grindon (1883), The Shakespeare Flora : Ellacombe (1878), The Plant-lore and Garden-
craft of Shakespeare. The Shakespeare-country, as more particularly the district around Stratford-
on-Avon in Warwickshire, is but 27 miles NW. of Oxford. The character of the flora is identical;
the same masses of woodland, alluvial pastures, and slow-moving streams are characteristic features ;
and the Avon at Stratford is closely similar to the Isis above Oxford. It is also interesting to note
that neither of these exponents of Shakespeare's botany, on general principles, appears to have been
very familiar with the ecology of the Stratford countryside.

Introduction 5

tion at all times of the year, covering an area represented by a 3-mile
radius from Carfax, or to the tops of the low hills surrounding the Oxford
basin. A little commonplace flora, fairly known, and above all lived with
all the year round, may prove quite as useful educationally as scrappy
attempts at covering a wider area, or concentrating on the solution of the
more spectacular problems of a few aberrant types. The text is thus
designed, not so much to cover the story of plant-life in general, or the
British flora in particular, as to suggest a simple method for beginning
on any Flora which may be encountered, using local plants as the material
provided. The older and time-honoured method pursued by past genera-
tions, of the isolated amateur who bought a local or British 4 Flora ', and
tramped the country in order to find all the species recorded, and so
complete his * Herbarium', is not only time-consuming but unscientific,
leading to species-hunting and the theory of the lost sheep, by which the
ninety-nine common plants are neglected in the transports of finding some
obscure or critical type * new to the district '-1

It is sufficiently obvious that the first problem will be to find out the
conventional names of the plants concerned, in order to check their specific
descriptions and biological peculiarities, as already chronicled in a copious
literature ; 2 but it is recognized that the first duty of any University or
teaching institution is to provide oral instruction, and not to leave the
beginner to waste his time and break his energies in preliminary exercises
which may be readily covered in class. Nor is there any need at this stage
of the world's history for the individual student to recapitulate either the
work or the ideas of his predecessors. It may be therefore clearly stated
that the necessity for oral instruction and facilities for obtaining it in the
Botanical Department are assumed.

The scope of the work falls naturally under separate headings : —

I. A preliminary review of the factors of the environment, and the general

relations of local plant-life to these factors, as emphasized more
particularly in seasonal change.

II. An account of the individual plant-forms included within the flora and

isolated as conventional species, constituting the more strictly Floristic
part of the subject.

III. The more intimate relation of the associated plants to their con-
ditions and each other, as determined by continued observation and
experiment, constituting what has become known as their Ecology.

For this last purpose, in addition to the general record of the flora,
a number of stations may be isolated, as generally typical — about 12
being considered sufficient for the purpose. These again are restricted
to sample tracts of small area (as stretches of 100-500 yards, or a few
acres), providing a partial flora of about 100 species, as a set convenient
to handle ; capable of being checked within an afternoon of 2-3 hours,
and of being followed throughout the year.

The point of immediate interest is to put down on paper the more
obvious data; and with these at hand, it should be possible to pass on
to more detailed examination. If the initial stage of record be omitted, the
whole subject remains nebulous and vague ; just as it is difficult for the
ordinary person in winter to recall and visualize the summer conditions of
hedge and woodland, or vice versa. Even to see what is obvious requires
eyes, and the vision of the outdoor botanist must be stimulated by a

1 Watson (1849), compiling early ecological data for his Cybde Britannica, notes (vol. ii,
p. 113) that the common Groundsel was not recorded for 20 counties, and the common Daisy
similarly passed unnoticed in 17 counties of Great Britain (loc. cit., p. 125).

3 Babington (1922), Manual of British Botany, loth edit. •

6 Plant-life of the Oxford District

laboratory training in the methods of modern science. The epoch of the
collector and systematist, as also of the amateur naturalist, whose elementary
knowledge of the structure and organization of the plants with which he was
dealing has been so conspicuously inadequate, has done its work. It remains
for the ecologist to carry on the tale, more particularly from the standpoint
of the life-problems of the plants themselves.

Such a record of the*obvious presents an initial difficulty in the effects
of rapid seasonal change throughout the year, to which plant-life responds
by presenting short vegetative and even shorter reproductive periods.
Large numbers of species come on, flower, fruit, and disappear within a few
months, and many are only available at their optimum floristic range for a
week or two in the year. Hence the efforts of many seasons may be
required to determine the biological relations of a single type, and such
investigations make slow progress. But it will be the more evident that
collective work is essential, and control by a departmental organization,
independent of the individual workers, who may also come and go as
the flowers of the field themselves, can alone be effective.

Again, in dealing with the plant-life of such a district, the botanist
is obviously primarily concerned with the plant-forms indigenous to the soil,
as developed under a rigorous and long-continued process of natural
selection. But as human activity seeks to dominate the flora, and to
convert it to its own uses, certain plants are encouraged as being more
valuable for food or other economic purposes, others are introduced, and
these are further developed at the expense of the original vegetation which
thus appears relegated to an inferior position, to be classed as ' weeds '.
In a district where human agency has thus interfered with every province of
the original flora, the botanist has at first to. work largely in terms of such
relegated weed-flora; whether as the residual forms of the forest under-
wood, the wild flowers of hedges and pastures, or the admitted weeds of
arable land, allotments, and garden-ground.

But that is no reason why the field -botanist should therefore confine
his attention to the primary flora and its vestigial representatives with
admixture of aliens as weeds of cultivation — his province is to deal with all
the phenomena of plant-life. Cultivated plants, their various sub-races,
their artificial selection, and their relation to the special biological environ-
ment of the district, are equally a subject for scientific analysis and experi-
ment. Hence no account of the indigenous flora can be complete without
the adequate recognition of these aliens of modern cultivation ; and the
latter become the more interesting as they may be of exotic or even
sub-tropical origin, modified by the skill of man, and still maintained in
a state of wholly artificial existence by the care of the forester, agriculturalist,
and horticulturalist.

Similarly, the extension of the indigenous flora to the cultivated flora
is further enlarged by paying attention to the lower types of vegetation,
as survivors of older phyla now relegated to inferior stations, filling the
gaps between higher forms, as Pteridophyta, Bryophyta, Algae, Fungi, and
even Bacteria, many of which appear as 4 pests ' of cultivation, in their
efforts to secure some sort of station and continuity of existence in the
strain of competition with the more advanced and successful forms of the
vegetable kingdom of to-day.

The business of the botanist is naturally to attempt to arrive at a
clear understanding of whatever plant-life may be around him. In a
tropical forest, where this phase of living organization is still dominant, he
may study vegetation in its most aggressive form. In a northern climate
where plant-life is struggling against the conditions of the environment, the

Introduction 7

varying features of the conflict afford the most interesting ecological
outlook. In a civilized country, where vegetation wages an unequal conflict
with both the environment and the aggression of human interference, he
must be content to deal with these combined effects, as, in their way, equally
likely to result in changes and possibly striking new departures in the plant-
story. The consideration of the admittedly deteriorated flora of the Oxford
district may thus serve as an introduction to the study of a more natural
area with dominant types of vegetation. There is no need either to attempt
to glorify it as being particularly unique, or to deprecate it as valueless.
The point is to present it in its exact relation, as a training-ground in field-
work for members of the Oxford Schools of Forestry and Botany, who may
be called on to deal with wider problems of plant-life in any part of the
world.

II. PHYSICAL FEATURES

Before dealing with the general physical factors of the environment
it is necessary to explain how it is that the Oxford district becomes
available for present investigation, and the part played by man in the
establishment of what is termed civilization from the original wild ; Oxford
being now a large urban centre, as well as a University, to which the local
flora appears at first sight as a mere trivial appendage, of aesthetic rather
than of essential biological significance.

Oxford,1 a town of some 60,000 inhabitants, which has given its name
to the University and also to the county of Oxfordshire, is situated on the
Upper Thames (Isis), in longitude i° 16' W. of Greenwich, and latitude
51° 49' N. The name suggestively indicates that the University and City
have grown up in the vicinity of a ford practicable for cattle over the
Thames (at Folly Bridge), marking the course of an old route running
North and South to meet the river road to Abingdon, and this is com-
memorated in the City arms. The centre of the town is still indicated by
a Four Cross (Carfax), as the former main road cut another track running
approximately E. and W., crossing the Cherwell by a ford near the
Botanic Gardens (Magdalen Bridge), and extending now to cross the
Thame at Sworford (E.), and the Isis at Swinford (W.). The fords were
ultimately replaced by bridges 2 still essential to the roads, but their original
usage implies the necessity for inter-communication in a district intersected
by several streams, for which the present town marked a convenient centre.
The ford-names still persisting may commemorate the ancient Saxon
practice of taking stock to market ; that is to say, the roads were tracks
for herding cattle locally, while communication with the outside world was
long maintained by the river. The fords were important as representing
shallow stretches of gravel bottom, with a gravel approach affording secure
foothold, in a clay district. A market at the best ford naturally followed.

Place-names of adjacent villages indicate that the early settlements and
routes belong to Saxon times. The older Roman road from Bicester and
Alchester to Dorchester, still remaining in part, avoided the low- lying flood-
areas as much as possible, and once across Otmoor, passed i\ miles to the

1 The word is first written Oksnaforda in the time of King Alfred, but may be merely a corrup-
tion of an older pre-Celtic place-name ; cf. local names as Oxey Mead and the River Ock at Abingdon.

2 The first bridge over the Thames (Grandpont), at Folly Bridge, was built by Robert d'Oili,
the first Norman military governor ; that over the Cherwell at Magdalen Bridge being Pettypont.
The Grandpont was probably a drawbridge, and may have been associated with a causeway.

8 Plant-life of the Oxford District

east, almost due N. and S. along the higher ground, through Beckley and
Stow Wood, ultimately to cross the Thames at Wallingford. There is no
special evidence of earlier cultivation or settlement in the valley, though
ancient British, as also Roman colonists, may have occupied higher ground
on the adjacent hills.1 Early West Saxons of the sixth century cleared the
lower levels as meadow and pasture- land, replacing the original scrub of
the valley swamp-area ; and the names of villages and hamlets following
the margin of the old flood-line sufficiently indicate the mode of settling
in this river-valley; cf. Marston, Cassington, Yarnton, Kidlington, Kenning-
ton, Appleton, Eaton, and Botley, Bagley, Cowley, Iffley, Radley, Medley,
suggesting meadow clearings,2 — Binsey, Hinksey, Osney, water flood-
meadows, and minor islands in winter. Older river-names (Thame, Thames,
Windrush, Ray, Evenlode) go back to prehistoric times, and the more
upland villages apparently indicate remains of British and Celtic settlements
on higher ground (300 ft. or more), Cumnor, Cuddesdon, Baldon, Foxcombe,
and possibly Headingt(d)on, Garsingt(d)on.3

The Saxon town, as central for a wide meadow area, with unlimited
pasturage for cattle and horses at all seasons of the year, became an
important royal city of Mercia, at the limit of its junction with Wessex,
commanding the approach from the West to the North in the angle of the
river (seventh centuiy). Taken by Wessex (752), and back again by Offa
of Mercia (7 79), it again finally reverted to Wessex (912) under Edward the
Elder. Burnt three times by the Danes (979-1010), and occupied by them in
the eleventh century, it had been again wrecked before the Norman Conquest,
and half the houses were derelict at the time of the Domesday Book.
The population at this time has been estimated at 1,700, and it is sufficiently
obvious that it was self-supporting. The military significance and political
importance of the town was probably due to its value for camping ground ;
a fact which lent it an increased significance as a convenient centre for
meetings and conferences.4 The City and the beginnings of the University,
said by University College to date to the time of King Alfred, grew up
more definitely from the time of the Norman occupation, under the control
of a Norman Castle commanding the river-approach (1071). In these early
times much of the land had already passed into the control of the Church,
as represented by Abingdon Abbey, which also collected river-tolls, and
the original city was a walled area occupying gravel mounds emerging but
a few feet above the winter floods, with Carfax as centre. The cultivated
areas of the outlying townships passed under the Feudal System of Norman
times, the Saxon small holders becoming villeins of the Norman manors.
The city received a charter from Henry I about 1130, and the first University
lectures (Theology) are recorded for H33.6

1 Remains of a Roman villa at Beckley, pottery on Hinksey Hill ; pottery at Sandford, and
a Roman horseshoe at 18 ft. deep in the gravel of New Hinksey (1922).

• Saxon place-names showed a general appreciation of ecological factors, owing to the fact that
they were essentially a cattle-rearing people, dependent on the maintenance of horses, cattle, sheep
and pigs, which also required to be fed. Woodland was wood, not forest ; a ley indicates an
artificial grazing ground as cleared land, as it is still used for artificial grassland (clover-ley). Open
rough grazing in the field (feld, feldt) implied open grassy waste, which when dry became heath-
land, and when permanently wet and waterlogged, moor. These terms have their equivalents in
Low German ; but for the upland pastures of rolling hill country, not a feature of the older German
formations, they borrowed the British word dun, as down, as also coombe (cwm) for a deep valley-
ravine : cf. Otmoor, Northmoor, Littlemore, and Cumnor, Coombe Wood.

8 Cf, Alexander (1913), The Place-names of Oxfordshire, for the obscurities of philology.

4 Plot (1705), Natural History of Oxfordshire, p. 21.

5 The oldest building known is the church and convent associated with St. Frideswide, said to
have been founded 727, placed on the rising ground immediately above the flood-area north of the
ford, now Christ Church (Cathedral, E. end). The castle-mound is the remains of an ancient earth-
work on the flood-margin , probably dating to the time of the Danes.

The oldest tree in the district is undoubtedly the Yew in Iffley Churchyard, possibly as old as

Physical Features 9

In early English times the main wooded mass of the country was
dotted with hamlets, each with its own communal arable and grazing land,
which in Norman times were affiliated as manors to large military land-
owners ; Robert d'Oili, the first governor, collected some fifty manors by
marriage with a Saxon lady. In the fourteenth century, following depopula-
tion and the decay of the feudal system, land tended to go out of cultivation,
cattle-rearing and the small holder again becoming dominant factors.1 In
the sixteenth century the country was still predominantly wooded (Camden,
1586) ; on the west there was continuous forest over the Boar's Hill district
from Wytham to Abingdon. Another great belt on the E. took in Shotover
and ranged N W. to Stanton St. John. Open waste and heath-land extended
over Bullingdon to Magdalen Bridge. Cutting of the woods went on in the
seventeenth century, in the time of the civil war ; and during the eighteenth
century, as the country began to settle down after the wars, agriculture
tended to improve, enclosure set in on a large scale, hedges were multiplied,
and the general aspect of the countryside began to approximate its present
appearance. Old main roads rose to the tops of the hills above the clay as
soon as possible, passing over open country without hedges ; the London
road over Shotover Plain, and the road to the west through Ferry Hinksey,
Botley, over Wytham Hill to Eynsham. Much of the inter-communication
of villages was by mere cross-country tracks, suitable for pack-horses rather
than wheeled traffic. Many field-tracks between farms became public foot-
paths ; others have been ploughed up, and the connexion lost, as has much
of the Roman road. Enclosures in the eighteenth and early nineteenth
centuries have completely changed the older order of the country, as the
advent of the railway has that of the urban area.2

The modern city has spread largely northward along the most con-
siderable gravel patch between the Isis and the Cherwell, extending some
two miles along the Banbury and Woodstock Roads, and again about a mile
eastward along the gravel patch of the Iffiey and Cowley Roads. The levels
of the water-meadows have remained largely unaffected, and the greater
part of this area is probably much as it was when first cleared ; but the
higher ground has been progressively deforested and put under agricultural
control, until little is left of the original woodland covering the undulating
land beyond the alluvial swamp-area. The city area is 4,676 acres, or
about 7 sq. miles.

In mediaeval times the City walls followed the flood-level on the river
side, as still seen in Merton Meadows, and the river-gates were on the rise
just above the Thames ford (Aldgate), and near the Botanic Garden (East
Gate) where the Cherwell widened over shallows. The land outside the
gates was utilized as the town-tip for refuse, which might be more or less
washed away by winter floods, as a simple and effective method of sanitation ;
or remained to raise the level of the. ground (as it is still employed in Port
Meadow), to be subsequently built over. A portion of this area was allotted
to the Jews for a burial-ground ; and such made-ground marks the original

the Norman Church itself (i 160). The tree is now some 25 ft. high, with canopy 55 ft. diam. ; it was
probably once pollarded to give pole-shoots: the trunk 6-8 ft. diam. is a mere shell, and the head
of foliage is formed by a mass of epicormic shoots which are continually produced.

Plot (1705), Natural History of Oxfordshire; Murray (1912), The Making of Oxford ; Enc.
Bnt., i ith edition, Oxford; Gunther (1912), The Oxford Country; Orr (1922), A short history of
British Agriculture : For general Oxford literature the volumes of Anthony Wood, Parker, Boase,etc.

As a picturesque ' City of spires ', Oxford is said to have looked its best at the beginning of the

nineteenth century ; Godley (1908), Oxford in the Eighteenth Century. At present the remains of

5lder City are buried in a mass of buildings, in which red-brick villas and rows of small inferior

houses are dominant, seen over a foreground in which railway, gas-works and allotment-areas are the

most conspicuous features. The population in 1789 was 8,300; in a hundred years it increased to

io Plant-life of the Oxford District

tract on which the Botanic Garden was planted (1632). This land had been
taken over by St. John's Hospital, which was later reconstructed as Magdalen
College (1458). The area was still liable to total submergence by exceptional
floods, until the ' New Cut ' was formed after the last record rise of 1882 (as
marked on the present bridge), and the level of much of the garden has been
raised above the flood-line ; though the Cherwell still occasionally tops the
garden wall when in full flood (5 ft. above summer level). The present
Departmental buildings have arisen as accretions based on greenhouses of
different epochs.1

The nature of the environment, to which the plant-life of the district is
subjected, may be conveniently considered from the standpoint of: —

(1) Climatic Factors, including sunlight, temperature, rainfall, etc.,
as meteorological conditions, and

(2) Edaphic Factors of soil and substratum, as essentially geological
in their primary relations, including the drainage system of the rainfall
in the form of springs and river-systems.

Climate.

Meteorological records for the Oxford district are readily available in
the detailed reports of the Radcliffe Observatory,2 taken over a period of
some seventy years, and few localities have been so thoroughly scheduled.3
On the other hand, meteorological data are often singularly ineffective in
dealing with biological phenomena, owing to the particularly complex nature
of the problems, and the difficulty in making the most essential records.
Thus mere rainfall data are of little use in themselves, without some knowledge
of the amount of water freely drained off, the humidity of the atmosphere,
and the deposition of dew on surface-vegetation. Probably hours of rainfall
would be more illuminative than a record of the actual amount. Similarly
the working value of sunlight in terms of intensity of photosynthesis bears
very little relation to the recorded ' hours of bright sunshine '. Where such
complex interaction of factors is concerned, the phenomena of plant-life,
as exemplified in delicate organisms to whom such factors are a matter of
life and death on a very narrow margin, probably afford a more reliable
guide than the efforts of the human observer in his attempts at the discussion
and tabulation of a few of the factors separately.

I. Temperature. The mean maximum temperature of the air, obtained
by averaging the means for the 12 months, is 56-39° F. (for 70 years,
1851-1920), and the monthly averages may be expressed by a curve from
43-46° (January) to 70-67° (July).

The corresponding minimum air-temperature is 42-45° F. ; from 34*37°
(January) to 53-28° (July). This indicates on the whole a temperate climate,
but does not present the effect of either summer heat or winter frost.

The highest air-temperature attained may be 94-7° F. (Aug. 9, 1911) ;
and 80-90° is commonly experienced on hot days in July, Aug., Sept. (91-6°,
Sept. i, 1906), rarely in May (83-1°, May 30, 1895; 85-5°, May 22, 1921,
B. G. O.). The winter months (Jan., Feb., Dec.) rarely rise above 60° (61°,
Feb. io, 1899). Sun-temperatures may exceed 150° (rarely); 153-7°, Aug. 9,
1911.

Frosts may occur commonly in any month but June, July, and August ;
but exceptionally in June (28-6°, June 25, 1918) ; while white frosts may occur

1 Gunther (1912), Oxford Gardens, p. 155.

2 Rambaut, Results of Meteorological Observations made at the Radcliffe Observatory, Oxford,
in 5 -yearly volumes ; Hi, 1916—21.

8 Records of the Thames are taken in great detail by the Thames Conservancy : local data for
the Cherwell at Magdalen College Laboratory. Rainfall and temperatures at the Botanic Garden :
cf. Daubeny Reports, J. J. Manley, Magdalen College.

Physical Features 1 1

in late August outside the town area. Records in the sheltered grounds of
the Radcliffe Observatory, however, are often 2° or more above those of
outlying districts. No frost has been recorded in July for 60 years, but
a drop to 33*5° occurred in July 1918.

The lowest temperatures recorded on the grass are —2-7° F. on Feb. 5,
1917, and — 0*1°, Feb. 8, 1895 (the coldest winter of modern times). A drop
to zero, as a cold blizzard on the afternoon of Feb. 4, 1917, and on the cold
Christmas Eve of 1860, is very exceptional. Frosts of more than ten degrees
(22° F.) may be considered less usual, and long spells of frost are rare. The
severe frost of 1895, over a period of practically 6 weeks, established a modern
record. Snow-fall is inconsiderable ; wholly wanting in some winters (1920);
the more usual case being one slight fall before Christmas, and another
some time after, with little permanence of the snow-mantle beyond a week.

The full range of temperature thus affords occasional examples of
Arctic cold, as well as Tropical heat ; but temperate conditions are still the
average experience.

II. Light. More remarkable is the low value of the sunshine record.
Less than one-third of total daylight is included as bright sunshine ; the
average * cloud ' ranging very uniformly from 75 % of the time in the winter
months (Dec., Jan.) to 63-67 % of the summer months (July, Aug., Sept.),
leaving the average hours of bright sunshine as only 1-38 in December to
6-42 in June. Yet maximum sunshine may extend to over 15 hours (i5'9)
June 28, 1921) in fine weather in May, June, and July ; while in the darker
months, maximum hours of sunshine may be occasionally 6-7. But in the
latter case it must be noted that with a low sun these are but equivalent to
the morning and evening hours of the summer, and numbers of hours are by
no means a fair measure of the photosynthetic value of the light. The year
1921 was conspicuous for the brilliant and long-continued hours of sunshine
throughout the dry summer into August, September, and the first half of
October. In the two last months the cloud average fell below 50 %.

III. Rainfall. Data for net amount of rain are most readily collected,
though the methods adopted are still open to minor errors. Wet weather
is on the whole remarkable for its generally even distribution ; a rough
working average of one day fine and two days wet, more or less, obtains
throughout the year. If no rain falls for a fortnight it begins to be regarded
as a drought. The yearly average (70 years, 1851-1920) is just 26 inches
(26-022), ranging from 18-056 (in 1902), and the exceptionally dry season of
1921 (14*95 i*1-)1 t° wet years with 37-712 inches (1903).

Such records are open to the objection that exceptionally heavy rain
for a few days may run up the total without any appreciable effect on the
climate as a whole. A maximum of 1-2 inches may fall in one day (2-010 in.,
June 14, 1903), or -| inch in one thunder-shower. April 25, 1908, is registered
as 1-839 in. falling as continuous snow. A heavy rainfall which may rapidly
drain away does not necessarily imply a wet year, the distinguishing feature
of which will be a small but fairly continuous supply, or a heavier fall than
usual in the summer months, associated with much cloud (1873). The
monthly average throughout the year runs very uniformly at 2 inches a month
(mean for 65 years) ; less in spring months, but more in the summer (2-528
July and 2-889 October). In extreme cases 6 inches a month may be
exceeded (Oct. 1903, 6-431 in.; Sept. 1896, 6-009 "*•)» usually with accom-
paniment of floods. Half the rainfall comes with a SW. wind.

1 In the exceptional drought of 1921, beyond one or two severe thunder-showers (Aug. 17), and
one wet day in September, there was continuous fine and dry weather from the beginning of February
to mid-October. In the meteorological records this appears as rain on 16 days in May and 16 in
August ; it being clear that dew is included in many cases as rainfall (even to -ooi in. on some days).

12 Plant-life of the Oxford District

Owing to the damp state of broad alluvial tracts, a high day-temperature
may result in fogs in the lower levels, especially in autumn and early spring ;
while a sub-saturated atmosphere is often predominant for long periods in
these districts, though the atmosphere on higher better-drained ground may
be dry and clear. The scanty ancient population in British and Roman
times kept to the hills, probably for military reasons. The Saxons cleared and
cultivated the lower levels, and were largely restricted to the damp valleys
by the necessity for a permanent summer water-supply for their cattle.
The original urban area, as also adjacent villages (Marston, Cowley, Wolver-
cote, Binsey, Botley, S. Hinksey), follow the distribution of gravel-patches
with better drainage than that afforded by the clay areas. More modern
villa-residences again follow the hills where possible, as at Headington (now
the second most densely populated area in the county), Boar's Hill, and
Cumnor Hill, the further extension of which remains still limited by deficiency
of suitable water-supply, restricted to scanty underground streams or deep
borings, and with no reserves in case of fire.

River Temperatures average from 46-5° F.as the minimum (March i),
to 55*2° as the maximum (Sept. i), with a conspicuous lag beyond the air
temperatures. In exceptional winters (1891, 95) all streams freeze, including
the Thames.1 In exceptionally dry summers all ponds and streams dry up,
except the rivers bringing water from beyond the district,2 and a few minor
hill-springs.

Soil Temperatures. The temperature is constant throughout the year
possibly at 66 ft., a depth too remote for the purposes of plant-life. Records
of the Radcliffe Observatory by Platinum Resistance Thermometers (1898-
1910) have been plotted for varying depths, showing that at the surface the
mean air- temperature is fairly followed, with maximum in July, though i°
colder in winter, and 3° warmer in summer. Lower levels show an increasing
lag at i \ ft., 3^ ft., 6 ft, to a depth of 10 ft, at which the curve for river-
water is very closely approximated (or 46-5° min., 56° max.), and the local
occurrence of water in the gravel prevented deeper records being taken.3

Meteorological records have been also kept for the Botanic Garden
since 1861. (J. J. Manley, Magdalen College Lab.) These records show a wide
range of variation from the official data of the Radcliffe Observatory, only
half a mile away, probably owing to the fact that the garden is at a low level
on the alluvium near the river, and even more sheltered than the grounds of the
Observatory on terrace-gravel.4

Thus the rainfall minimum of 1921 was registered as 13-96 in.
The record cold of Feb. 4/5, 1917, is seen to have been due to local
blasts of blizzard intensity ; the minimum temperature on the grass that night
being 20°, and a foot above the grass 4°.

The record hottest day, July 10, 1921, gave 85° in the shade, and 128-5°
in the sun. In July 1921, the sun-temperature (absorption of radiant energy
measured as heat) did not exceed a maximum of 130-5,° and the hottest day
ever registered at the gardens (Aug. 9, 1911) was 91-3° in the shade, and
132-5° in the sun, as opposed to 94-7° and 153-7° respectively, at the Radcliffe.

1 A coach and four was driven on the ice from Folly Bridge to Iffley, and the river was free for
skating 10 miles below the City: Port Meadow flooded and frozen admitting skating to Wolvercote.

8 In the drought of 1921 the Cherwell ceased to flow, the bed being dry at Islip in September,
and the water only held up locally by the lock at Iffley.

3 It is clear that this water was a running stream (Timms).

4 Gunther (1916), Daubeny Laboratory Register, p. 172.

Physical Features 13

Geology.

Oxford Clay : The beginnings of plant-life in the Oxford district, so
far as available, may be said to go back to the horizon of the Oxford Clay,1
which forms a deep pan under the city and immediate neighbourhood,
200-400 ft. thick in places, apparently impervious to water, and covering
Lower Oolitic strata, the outcrop of which comes to the surface away to the
west on the Witney side, with the nearest outliers on the north, as the
Cornbrash of Islip and Kidlington.2

This clay represents fine silty material laid down as subaerial denuda-
tion of the continental fringe, in shallow and warm sea-water, probably in
broad, more or less land-locked lagoons of estuarine nature, as indicated by
the massive oyster-like Gryphaea dilatata, which may lie in banks or as
thickly distributed dead shells.3 The conditions of a warm sea are also
illustrated by the presence of Ammonites and other Cephalopods (Belemnites).
The clay is remarkably uniform in texture in the upper levels more com-
monly exposed, and the blue colour is due to ferrous sulphides which oxidize
on exposure to yellow-browns of ferric oxides. This probably indicates the
wastage of an adjacent volcanic land-area, as iron is practically negligible in
the water of open seaboard.

At the base of the clay the material becomes more shaly (Kellaway
beds), of hard sandstone with calcareous debris, occasionally bituminous with
traces of lignite and iron, as the indication that the clay-deposit followed
a depression of previous forest-land, with algal fringes, sinking and gradually
covered with coral-reefs in shallower areas. Similar traces of lignite have
been found in the deep boring (Brewery, 1898) at depths of 375, 396, and
406 ft. beneath the City in similar shales and limestones of estuarine beds
of the Lower Oolite.

This first vegetation of the Jurassic (Mesozoic) may have been of any
tree-forms of the present world, Gymnosperm or Angiosperm ; since at the
time of the Upper Cretaceous plant-life of the world was to all Botanical
purposes as good as it is at the present day. Angiosperm forest timber-
trees,4 flowers with syncarpous ovaries,5 occur in Cretaceous deposits ; winged
land-insects in the Jurassic, even a butterfly. The time required for their
evolutionary progression to this level is still beyond computation ; but is
probably to be estimated in hundreds of millions of years.

Though this great bed of blue clay constitutes so bold a feature in the
local succession of strata, it represents but one of many long-continued
periods of depression and elevation, following on from the older Lower
Oolitic sea-floor, as the land on the fringing margin (Continental shelf,
100 fathoms) of one of the main surface-folds of the earth, rising from the
3 mile deep of the Atlantic Ocean, which may be visualized as expressing
oscillatory effects with the rhythmic progression of the tide-periods of the
ebb and flow of the ocean.6 Taking the Upper Cretaceous as representing

1 Pocock (1908), The Geology of the Country around Oxford. Memoirs of the Geological
Survey, with accompanying Map in colours, I in. scale, and section E. and W. through the City area.

2 Cf. Islip Railway-cutting.

3 In great quantity in Iffley Road cuttings, 1922, to 8 in. : smaller forms 3 in. in the Wolvercote
brick-pit ; in other cuttings often wholly wanting : remains of timber in clay nodules, corroded and
infiltrated with silica and iron pyrites, occur generally in upper Oxford Clay of the Wolvercote pit.

4 Slopes (1912), Phil. Trans., Petrifications of the Earliest European Angiosperms (Lower
Greensand). All such timber from the Oxford Clay, so far examined, was definitely Coniferous,
showing uniform tracheides and medullary rays.

5 Slopes (1910), Annals of Botany, p. 679, Cretovarium.

6 Such oscillatory effects may be roughly indicated by noting that the present land- level of the
Oxford valley is but 200 ft. above the sea, and a drop of a foot in a thousand years would take it to
the bottom of a 30-40 fathom sea (comparable with much of the present North Sea area) in about
500,000 years. Such a sea at sub-tropical temperature would be full of life, both plant and animal.

I4 'Plant-life of the Oxford District

a time-period of some 150 millions of years ago, there is ample time for
a quite indefinite succession of such horizons, as depression to varying
depths, and subsequent elevation and denudation, may involve successional
strata of calcareous coralline deposits, clays and shales, sandstones and
limestones, as the expression of rhythmic oscillations of even million-year
periodicity. Successional strata of clays and calcareous sands and limestones
in alternating series are the characteristic feature of the district, and such
successive strata do not lie conformably on one another ; as these main
earth-movements have been associated with minor local oscillations, the
effect of volcanic disturbances, and the possibility of repeated exposure as
a land-surface, subject to subaerial denudation which may cut through several
older beds.

Such periods may have been repeated over and over again for indefinite
hundreds of millions of years before. Rocks of Liassic age thin out below
the district, implying that there was more land exposed at that time ; and
these in turn rest unconformably on the far older deposits of the Carbonifer-
ous, below which are indications of deposits of Silurian seas. Taking the
Carboniferous as some 400 million years ago, and the Silurian as 600, even
these horizons are probably but a short way to the time of the first elevation
of land with the sea-weed vegetation of the sea.

The entire history implies indefinitely continued oscillatory exchanges
of an old continental seaboard, with occasional variants, as larger denuda-
tions introduce estuarine conditions at the outflow of great continental rivers.

Omitting the higher beds of sands (Greensand) and clay (Gault) which
are left as mere relics on the tops of surrounding hills, the Oxford district is
built on three main systems : —

(i) Oxford Clay, giving clay soils at lower levels.

(a) Calcareous Grit and Coral Rag (Corallian Series), on rising ground.

(3) Kimeridge Clay, giving clay soils at higher elevations, and also on
low ground to the SE.

In further detail, the Oxford Clay, though normally following an
indefinite sequence of marine deposits of Coralline limestone of the Lower
Oolite (Jurassic), to the Lias touched at a depth of 430 ft. below the
City, as : —

(A) Inferior Oolite (Limestone), Chipping Norton.

Great Oolite (White Limestone, ' oolite ', and marl) with estuarine beds.
Forest Oolite (Clay and Limestone), Hanborough, Islip, Witney.
Cornbrash (Limestone), Witney Bridge,
is in turn covered locally by : —

(B) Lower Corallian of Calcareous Grit and Sands, Headington, Cowley, Littlemore.
Upper Corallian of Coral Rag and Coralline Oolite, Headington Quarry,

Cumnor Hill.

A deposit of a foot of silt in 1,000 years while moving would give 300 ft. of deposit in 300,000 ; and
at the same rate of re-elevation 200 ft. to the sea-surface, a million years becomes a small unit in
accounting for the depression, deposition, and elevation of such a geological horizon. On a globe
i metre diameter the total range of such oscillation would be represented by a distance of 10 /*.

These speculations are warranted from the estimates given by chemists for the disintegration of
radio-active minerals found in older rocks. Such data are accepted, in absence of any other means
of calculation, because they suggest agreement with the enormous distances of time required to
explain the slow evolution of plant-life, as itself the most delicate response to the changing conditions
of geological time (Holmes, 1920, Discovery, p. 112).

It is hardly realized yet that the enormous times suggested by these chemical deductions supply
the one factor needed to make the biological machine work throughout the ages, at a rate no
greater than things are changing at the present time ; and that it was for want of these remarkable
data that previous generations of biologists have failed to grasp the full significance of ' natural
selection ' over spaces of time, which to our senses are inconceivable, and what the history of life on
this world really implies. At the Brit. Assoc. Meeting, 1921, Lord Rayleigh suggested some 8,000
million years as the possible age of the earth, and geological ' time ' begins to bear a reasonable
relation to astronomical ' space '.

Physical Features 15

Kimeridge Clay, Boar's Hill, Horspath, Bagley.
Portland Beds (Sands and Clay), Shotover, Garsington.
Purbeck Beds (Limestone and Sand).

Wealden, Shotover Sands with Clay and Ironstone, Garsington Hill.
Lower Greensand, Boar's Hill, Cumnor Hurst.
Gault) Clay, Cumnor Hurst, traces only.
To a much more recent age belong : —
(C) Plateau Gravel, Boar's Hill, Bagley.
Valley Gravel, Oxford City.
Brick Earth and Alluvium.

as the expression of the debris of the ' Glacial Epoch ', and the enormous
denudation following it, in the cutting of the present river-beds with their
gravel * terraces ' and present alluvial and winter-flood area.

In the restricted Oxford district, series (C) remain only as casual
deposits, with little reference to the subjacent primary construction ; though
significant from the local standpoint of surface-soils. Series (B) are left
residual on the surrounding hills, and are denuded to the clay over a greater
portion of the plain-area. Series (A) are not exposed within local range,
nearer than Islip, but may be found by boring ; just as Palaeozoic rocks of
the Coal Measures are indicated at a depth of possibly 1,000 ft. (said to be
1,200 ft. at Burford) ; though no coal or plant-remains have been so far
recorded.

Plant-remains of higher beds may occur in estuarine deposits, as the
sites may have been connected with great continental river out-flow ; but,
also, have not been recorded. The outstanding feature of the whole story
is the prevalence in all older times of a warm climate, warm seas with coral-
reefs, gigantic estuarine formations implying forest-land, with the ground
rising or falling over long periods of elevation and depression, or wholly
changed locally with the lateral deflection of the estuarine deposits, following
presumably alterations in the formation of adjacent predominant land-
masses.

The Corallian Series : Of the surface of the Oxford Clay beneath the
later deposits little is known ; the soft material shows little bedding, and it
is not clear whether it was elevated and in part denuded before again sinking
in the Coral Sea of the Middle Oolite. Probably it was thoroughly denuded,
hummocked, pitted, and dried, as tundra-like formation, giving shrinkage
cracks to be filled later with sand-debris, which may become utilized as
channels for subterranean streams.

The next beds show mixtures of sands and stone, as Calcareous Grit
of Lower Corallian, ranging 20-60 ft. thick, with characteristic Corals, large
Ammonites, and Mollusca. These again express a sinking coast, with in-
shore deposits as sand-bank formations in clean water. In places the beds
become shelly, and at Headington a layer of pebbles (8 in. thick), with rolled
material and shells, indicates an ancient beach ; so that land was exposed
close at hand. In other parts there is no appreciable break in the sea-
deposits. The most characteristic exposure is the deep bed of sand in the
railway-cutting near Littlemore Station, 8 ft. thick, with massive septaria
concretions, excavated for nests by sand-martins, and utilized for foundry-
castings by the railway company. Sandy soils, cultivated as arable land,
are characteristic of higher ground at 300 ft. at Hill Top, Headington, and
also at Cowley, Littlemore ; but in these the lime is commonly deficient,
having been leached out. The woodland area of Tubney is on soil of the
same nature.

Later deposits of Coral Rag (Upper Corallian) do not rest conformably
on the preceding, nor necessarily conformably among themselves ; the
boundary between the two series may be ill-defined. Corals were particu-

1 6 Plant-life of the Oxford District

larly fine at this period, expressing massive reef-formation (cf. Honey-comb
Coral Isastraea of Cumnor and Headington). Limestones may be so hard
as to be utilized for building-stone in numerous local quarries (Headington
Quarry), as the inferior building-material of the district. Such beds extend
to a thickness of 12-40 ft., and are characteristic for Headington. Lime-
stone rocks, cut down to Calcareous Grit sands, are still worked at Heading-
ton, and Coral Rag land, with abundance of broken corals, is seen in the
large arable fields of Cumnor, N. Hinksey, Wytham Hill, Headington,
Elsfield,Beckley and Kennington, as also on the western slopes of Boar's Hill.
The upper limit of the Coral Rag gives, again, sands of more inshore
deposits, and the upper surface of the stone may be water- worn, indicating
exposure as land before it sank again to repeat a clay deposit of the
Kimeridge horizon. Estuarine conditions were probably never far away ;
clays with nodules appear in the Upper Corallian of Littlemore, and the
Ampthill clay which comes to the surface 7-8 miles to the east, at Waterperry
and Worminghall, belongs to the same period. The most characteristic
exposure is that of the railway-cutting at Littlemore, showing successive
strata from clay with nodules above to a basal layer of hard rock covering
the sandy mass of Calcareous Grit.1

The following Kimeridge Clay expresses again the silty estuarine
deposit of a denuded area of volcanic activity ; iron and sulphur in quantity
being mixed with the lime debris of the sea. The dark clay is coloured
with ferrous sulphide and carbonaceous matter which may indicate vegetable
debris and algae drifted with the slow current. As in the case of the Oxford
Clay, the deposit is that of a shallow sea full of life, including great saurians
(PleisosauruS) Ichthyosaurus} and common shells (Cardium^ Pecten> Pinna)
of recent seas, as well as large Ammonites (Chawley cutting) and oyster
shells (Ostraea deltoidea, Headington), but no longer Gryphaeas. At
Chawley Brickworks strata indicate masses of mud with debris of empty light
Ammonite shells, as if floated to the limit of the tide-mark, suggesting
estuarine beach-levels. At Shotover this clay is estimated at 100 ft. thick,
with again traces of lignite. The most characteristic exposure is that of the
cutting at Chawley, which is encroaching on Cumnor Hurst. This clay
forms the greater part of the soil of Bagley Wood, as well as broad areas
under Shotover, and to the south of Garsington Hill.

Above the Kimeridge Clay the conditions again conspicuously change to
sandbank formation with clean water, giving * Greensand ' with glauconite
(but now red with iron), and white coral limestone. The lower beds, about
60 ft. thick, are again separated from the upper 40-50 ft. by narrow clay
bands. At Shotover the whole may be 100 ft. thick. These imply a long
period of clean sea- water and coral-reef; though some may have been since
metamorphosed by permeation of silica and iron.

Together with these, other traces of Cretaceous deposits also occur as
Portland Beds, capping the more hilly districts to the SE. (Baldon, Milton) ;
and though these may be insignificant in floristic value, they remain the
only guide to the progression of the formations and the condition of the land
throughout the rest of the Cretaceous epoch well into the Tertiary. Traces
of Purbeck beds, following on after the Portland beds at Shotover, are seen
at Wheatley and Garsington ; the special interest of which centres in the
fact that they are more distinctly estuarine, grading into definitely fresh-
water deposits with fresh-water shells (Planorbis). In these Garsington
deposits fragments of Coniferous wood occur, indicating the debris of forest-
land ; while traces of an actual land- surface soil of this period have been
noted 10 miles away to the NE. at Brill.

1 Pocock (1908), loc. cit., p. 35, for detailed description.

bb

Physical Features 17

Isolated patches of sands on Shotover, and at Brill, indicate apparently
river-deposits of fresh water of the Wealden horizon; the sands being mixed
with clays, and showing patchy deposits of river-sediments. Sandy deposits
of similar character, also mixed with clays, are also left in isolated pockets on
higher ground, more particularly on Boar's Hill and Cumnor Hurst, where they
yield no fossils and rest directly on Kimeridge Clay. These appear to be of
marine origin, and the intervening Portland beds must have been denuded
before their deposition as Lower Greensand.

Small traces of a still higher clay at Boar's Hill, Toot Baldon, and Cumnor
have been identified with Gault, which is predominant away to the SE., as the
third great succession of an estuarine clay.

No trace remains of the Upper Greensand which represents the next
clear- water deposit, nearer than Chalgrove, 10 miles to the SE. ; nor does the
Chalk come any nearer than 12 miles at Wantage and Wallingford, with an
outlier as Wittenham Clumps ; though it is probable that the whole district
was once covered with a great depth of Chalk-formation of warm and
shallow sea.

Since this time, it would appear that the land has been wholly out of
the water, and subaerial denudation has wiped off these later deposits, leav-
ing only ridges and patches of the Middle Cretaceous beds as the caps of
the low hills of the district. Even before the exposure of the vestiges of
Gault and Greensand on the adjacent hills, possibly 800 ft.1 of a general
Gault clay bed, with superimposed Chalk hills, had been cut away by
erosion over a period of possibly 100 million years. This marks a wide
gap in the geological story ; but the record, continued with warm seas, coral-
reef, estuarine beds and the mighty rivers of the older continental area,
over Mesozoic times, implies a land-surface of continental connexion with
a vegetation far surpassing that of present times for the same locality, of
which no trace remains. Of the land-conditions extending into the Early
Tertiary Period (Eocene, Miocene), again, nothing is known ; only in the
late Pleistocene is the tale picked up again with the changes effected at the
last * Glacial Epoch ' which is responsible for the surface-modelling of
the district, as the Jurassic period has afforded the main material.

Surface - Modelling.

Post-Glacial Erosion : Only in the latest deposits of the Pliocene period
is there any definite indication of the Pre-glacial flora of Great Britain, as
presented more particularly in the Cromer Forest-bed,2 as a formation of
estuarine swamp and lakes, with a temperate climate, to all botanical intent,
identical with that of the present age. Large mammals still remained, and
tthe Oak was a dominant tree,3 just as at the present day. This fact, as also
the way in which the Oak is replaced in a slightly colder climate by Pinus
sylvestris, and in a slightly warmer one by the Beech,4 very exactly defines
the general nature of the flora, as essentially ' English ' in aspect. With
such a climate, and continental land-connexion, there can be little doubt
that man of low-grade types, at the limit of the northern dispersal of the
human race, had followed the plants and animals on which he subsisted.

These pre-glacial plants of the latest Pliocene, found on the coasts of
Norfolk and Suffolk, are still characteristic of the British flora, with only
a few additions suggestive of a more continental range (Picea excelsa^ Trapa
natans). Recognized examples include : — Coniferous trees, as Juniper us y
Taxus, Pinus, Picea ; Angiospermous forest-trees, Oak, Beech, Alnus, Betula,

1 Pocock (1908), loc. cit., p. 107.

2 Clement Reid (1899), Origin of the British Flora, p. 35.

3 C. Reid (1913), Submerged Forests (Post Glacial), p. 106.

4 Warming (1909), Ecology of Plants, Eng. Trans., p. 203.

B

i8 Plant-life of the Oxford District

CarpinuS) Corylus^ Acer campestre^ Crataegtis, Pyrus Aria ; minor wood-
land-forms, as Cornus sanguinea^ Rubus fruticosus ; familiar herbaceous
types, as Ranunculus repens, Heracleum, Lapsana communis^ Solamim Dul-
camara ; aquatics, as CaWia, Hippuris> Hydrocotyle, Bidens tripartita, Men-
yanthes trffoliata^ Mentha aquatica, Lycopus^ Sparganium, Potamogeton,
Phragmites communis and Osmunda?

The advancing waves of cold of the Pleistocene, commonly fore-
shortened to our perception as a ' Glacial Epoch ', culminated in an ice-
sheet over practically the entire country ; and the British Isles, together
with Northern and Central Europe, passed into a condition which has been
compared with that of Greenland and Spitzbergen at the present day.
A vast ice-sheet covered the mountains of Scandinavia ; the North Sea was
frozen, and glaciation extended as far south as the Thames Valley, entirely
blotting out the flora of the northern parts of Great Britain, except for
the possibility of the survival of a few residual Arctic types on isolated
hills, and attempts at a residual vegetation in the non-glaciated strip, south
of the Thames, over a short summer-season, much in the manner of the
flora of Spitzbergen at the present day. The subtropical vegetation of the
Tertiary Epoch wholly disappeared, and the mean temperature must have
been near the freezing-point most of the year. Arctic Willows have been
traced in Devonshire ; while the extension of winter ice-sheets is shown by the
erratic boulders floated as far as the Isle of Wight, and even across to France.
As the Oxford district is just beyond the southern limit of known glacia-
tion, it is evident that the whole of the modern flora must have been immi-
grant since the time of maximum cold, however mild and temperate may
have been any long-continued * Interglacial Periods '.2

The revival of the temperature similarly implies long-continued oscilla-
tion phases, just as does the advance of a modern spring on a smaller scale,
and the so-called Palaeolithic epoch commences with the first traces of man
and his stone-implements. The country was gradually re-afforested ; the
flora as we know it was introduced from the adjacent continent ; large
mammals as the Mammoth and Woolly Rhinoceros followed ; and with
them came primaeval hunters living on fish, wild fowl, and anything avail-
able.3

No trace is left in the Oxford district of such times ; the older strata
are worn down to the level of the Oxford Clay, and superjacent strata are
only left in patches, constituting the hills around the City. Much of these
may have been denuded before the deposition of the Upper Cretaceous.
The present modelling of the country is largely Post-Glacial, and has been
effected by water-erosion ; though to a certain extent the direction of the

1 C. Reid (1899), loc. cit, for complete schedule, p. 171. The flora was at this time dominant;
and man, if actually existing in this land at that time, had no effect on the vegetation : ' He was
only one more carnivorous animal added to a fauna which already possessed several quite as dangerous,
and apparently occurring in greater numbers ', loc. cit., p. 38.

2 C. Reid (1899), loc. cit., p. 171, for schedule of Interglacial plants.

As vestiges of permanent glacial ice still remain at 3,600 ft. on the Cairngorm Mts., at a
distance of 400 miles from the Thames Valley, it might be supposed that the extension of the ice-
sheet this distance farther south was really only a minor climatic phenomenon in the history of
N. Europe. Much of the difficulty of the Glacial Epoch appears exaggerated when seen fore-
shortened, and changes in proportions of sea and land with diversion of oceanic currents, as the Gulf
Stream, might bring on a similar condition of things. Spitzbergen enjoyed a subtropical climate
with fauna and flora to correspond in the Miocene.

Cf. Brooks (1921), Nature, Sept., p. 90.

3 The heroic primal hunter chasing the Mammoth with a flint axe is probably a myth. The
first immigrants were undoubtedly a squalid race, the outcasts of the old world, with little knowledge
beyond that of fire, flint, and sticks. At any rate man in N. Europe was already indefinitely old, and
his tropical origin forgotten. Confusing decadent races, since apparently ' simple ', with the actual
stages of up-grade evolution, is sufficiently familiar in Botany, and is common to other biological

Physical Features 19

main streams indicates an older drainage-system of pre-glacial denudation,
leaving channels to which the water returned after the melting of the ice.1

In the excessive denudation of this epoch, the whole land-surface was
mobile, and torrential streams have swept out broad river-valleys, leaving
gravel deposits on their sides to mark the strength of the current, and giving
rise to a. residual system of water-courses, which at the present time
dominate the surrounding country and its recovered flora.

The primary river-beds are of Pre-glacial and Tertiary origin, following
the direction of the dip of the strata to the SE., and mark furrows between
ridges 6-7 miles apart, of which traces are left in the Wytham-Boar's Hill
and Baldon series, and the Shotover-Garsington-Milton line bounding the
lower valley of the Cherwell, and again NE. in the hills at Brill.

The Thames itself is of later origin, as cutting across the line of the
Oxford Clay from its source to Yarnton, at right angles to the preceding
lines of flow, and hence ultimately reaching these streams ; the great loop
of the Upper Thames (Isis), north of the district, being formed by the river
cutting into the course of the older Evenlode at Eynsham, and then into
the Cherwell valley at Kidlington, to spread out over a broad area, 2-3 miles
in width, and leaving gravel deposits dropped in successive steps to mark
its ancient course, as also the periodicity of its torrent-flow, with alternating
periods of less active action and deposition of alluvial mud only, as charac-
teristic of modern times. The older the stages and the broader the valleys,
the more vestigial are the traces remaining, and the deeper hollows of the
valleys are now spread over by alluvial mud in which run the present diminu-
tive streams.2

Plateau Gravel. Special interest attaches to the highest deposit of
gravel at elevations of 100-350 ft. above the present river-bed ; since it
does not consist of local material, and was not laid down by existing streams.
It consists predominantly of siliceous quartzose pebbles derived from more
Northern sources, and is hence distinguished as Plateau Gravel of the
Northern Drift, left as water-worn or glacial detritus in pockets and patches
on old valley slopes, without any bedding or terrace-distribution. Such
constituents are large Bunter Pebbles of the New Red Conglomerate from
the Midlands, traced to the valley of Moreton, white quartz, variously
coloured quartzose, sandstone of the Millstone Grit, and residual flints
from the Chalk. The stones are rounded or sub-angular ; but do not pre-
sent any glacial striae. Smaller pebbles of this drift may have been washed
into lower gravel deposits, and mingled with them ; but all are to be dis-
tinguished by being non-calcareous ^ as opposed to the river-drift from oolitic
rocks of marine coral-formation.

Erratic pebbles (up to 8-10 in.) occur abundantly on Boar's Hill ; but
there is no such drift on the Shotover side of the valley. A bed of such
pebbles resting on Gault at Cumnor Hurst is 12 ft. thick, and 8 ft. on Boar's
Hill; these spots being 290-350 ft. above the river. Patches in Bagley
Wood have determined the direction of the higher Abingdon Road : the
stones are imbedded in a reddish clay. The drift is regarded as glacial in
origin ; 3 but it probably represents the debris of older mountain torrents of
the primary river-valleys, collected and distributed by later ice-sheets of the
glacial epoch. At any rate, it is clear that if the high valleys of this period,
so far little cut, were filled with ice to this level, i. e. 500 ft. above the sea,
the protruding tops of the highest hills, even if much higher than at present

1 Pocock (1908), loc. cit., p. 106.

2 Pocock (1908), loc. cit., p. 82. The depth of the alluvium in the centre of the valley is about
that of the river, the main stream running on a gravel bottom with mud at the sides.

8 Pocock, loc. cit., p. 102.

B 2

2O Plant- life of the Oxford District

(Shotover is only 560 ft.), could have carried but the scantiest traces of
vegetation.

The River Gravels and Terraces : So long as the land was more or
less swept by the ice-sheet, the distribution of gravel was effected by glacial
drift ; but as soon as the ice melted, the Greensand and Corallian formations
were again exposed to denudation, with the other beds of sand and stone
forming the caps of the higher ground. The river-torrents, loosening the
entire hill-sides, and fed by melting ice, brought down immense quantities
of gravel of characteristic small limestone pebbles, stained yellow-brown
with ferric oxides, and with only a small admixture of the older drift, as
a post-glacial deposit. The streams flowed apparently at much the same
low gradient as at present, with recurrent annual floods, and they swept the
mass of the material down the Thames Valley to the sea ; but they left
gravel deposits or banks at the flood-levels, especially at points where the
main current was checked in flow by the influx of a lateral tributary.

Interrupted at least at three special horizons, such gravel deposits are
distinguished as giving 4 recognizable * Terraces ', at successive levels on
the river- valley margins, separated by periods of more gentle erosion.
These latter evidently represent cycles of warmer and colder climates ; the
less-marked erosion being the result of a mild winter, with little accumula-
tion of snow and ice, and characterized by the animals of a warmer climate,
as at the present day ; the gravel terraces themselves being the indication of
renewed cold and an intensified flood-system at the melting of the snow in
the Cotswolds, and presenting indications of sub-arctic animals.

The Highest Terrace (' Fourth ') J is 70-100 ft. above the present level
of the river, as well as 50 ft. above the next below. Between Kennington
and Radley there is a deposit 80-90 ft. above the river with abundance of
oolitic pebbles. A similar terrace at Long Hanborough is 90 ft. above the
Evenlode.

The « Third ' Terrace, formed after a long period of gentle erosion had
cut the valley down another 50 ft., is left only as traces at Wolvercote, at
40-50 ft. above the river, at a level 30 ft. higher than Carfax. Fossil
remains from this Quaternary bed indicate a cold climate with a peat bed?
some Alpine plants (Mosses) not known in the district, together with some
of the present flora, as also bones of Mammoth, Horse, and Reindeer,
together with fine flint implements ; the last being the first traces of human
activity in the neighbourhood, and showing that man returned with the
larger animals.

The ' Second ' Terrace, some 20-30 ft. above the level of the river, is
largely constituted by the great gravel-bed on which the city was built,
extending from Carfax along the Banbury Road for about 3 miles, as not so
much a ' terrace ' as a broad pebble-ridge, now residual between the present
bed of the Isis and that of the Cherwell, and ranging in some parts to 30 ft.
in depth, commonly 12-20 ft. Bones of Mammoth, Woolly Rhinoceros,
Hippopotamus, Horse, Lion, Wolf, Pig, and Reindeer have been recorded.
The gravel may be 9-12 ft. deep in the centre of the town, with more
admixture of clay than in North Oxford ; the base of this gravel is about

1 The numbering of these Terraces, following Pocock, loc. cit, p. 90, might with great advantage
be reversed in sequence, the highest being so obviously the ' first ' in order of time, however much it
may be the ' fourth ', and also the least definite, in going up from the river.

2 A. M. Bell (1904), Q. J. Geolog. Soc., 60, pp. 120-132. A certain amount of error attaches to
such determinations where the material is not collected personally with due precautions. Recogni-
tion of actual species from mere fragments of seeds and fruits is often open to suspicion, though the
genus may be correct. Wind-borne seeds from adjacent weed-vegetation are readily drifted into
cuttings, as well as material brought on muddy boots. Mr. Bell's material was looked over at the
Botanic Dept. as mere slides of fragmentary de"bris. One of the likeliest-looking collections of seeds
was planted in the garden and came up Chenopodium album.

Physical Features 21

half-way down St. Aldate's. Adjacent villages, as Marston, are on outlying
patches, and the Iffley and Cowley Roads follow another ; the gravel thin-
ning out in pockets along the Iffley Road to Fairacres.1

The Lowest and Last Terrace (' First ') rises only 5-10 ft. above the
flood level of the alluvium, and is seen as small patches of gravel ; the most
characteristic being that of the St. Aldate's side of Folly Bridge, taking off
as the second terrace gives out, and forming on the other side of the river
the base of New Hinksey.2 Small banks give the foundations of Lower
Wolvercote, Binsey, N. and S. Hinksey, and the terrace is conspicuously
marked in N. Hinksey fields, part of Port Meadow, and along the river-bank
from Radley to Abingdon. It is largely covered by the alluvium. An
isolated pit at Donnington gives inferior gravel with sand 8 ft. deep, in which
teeth of Woolly Rhinoceros and Mammoth occur, again with stray flint
implements as the water-carried debris of the Thames Valley. These
materials may be of any age ; just as Plateau drift pebbles are found as the
base of the higher Terraces, and bones of the Mammoth in the alluvium
and gravel of Magdalen Grove.

The River-' terraces ' are more readily visualized as sand-banks once
submerged, but now left high and dry with the fall of the river in the eroded
valley. Gravel detritus would be dropped wherever the velocity of the main
current was checked, as beyond a bend, spreading over flats, or where a
tributary stream ran into the main river at right angles.

The Isis, cutting NE. along the Oxford Clay across the older valleys of
the Windrush and Evenlode, stopped all gravel coming down these tributaries,
forming the broad bank of gravel on the left bank of the stream (Stanton
Harcourt, Eynsham, Yarnton). The highest terrace is beyond the range of
the district at Hanborough.

At the confluence of the Isis and Cherwell, the 'third' terrace of Brick-
earth, above Wolvercote and Peartree Hill, remains as the vestiges of a sand-
bank, south of which the converging streams threw up the gravel-ridge of the
long city patch in the middle line of their course, and the line is continued
between the two residual streams as the ' First ' Terrace of New Hinksey. The
fact that both the present streams of the Thames and Cherwell cut through
these gravels, explains the significance of the older fords at Folly Bridge
and Magdalen Bridge as the only spots with a gravel approach on both sides
of the stream.

The Marston gravel-patch indicates a sand-bank thrown up at the con-
fluence of the Cherwell and the Bayswater Brook, and it is composed of
material from the valleys of Barton and Headington. The Donnington gravel-
bank is a smaller deposit at the confluence of the Bullingdon Brook and the
Isis, and is built up of layers of gravel with thin strata of sand from the
Calcareous Grit of the Bullingdon Valley. The best pit (10 ft. deep, 1921)
shows very distinct layering, and the gradient of some of the layers suggests
that the main flood-stream drove back into the valley of the tributary.

At its widest, from Wytham Hill to Elsfield, the full stream was some
5 miles wide, as a flood-area narrowing to the Sandford end, where it was
never more than a mile wide. The stream at the ' Second ' Terrace horizon
was two miles wide over the City area; little over a mile at the alluvium
between the Castle and Botley, where it is now restricted to half a dozen
minor streams.

Special interest attaches to the ' Third ' Terrace of Wolvercote, partially
exposed at the Brick Works, as it is largely composed of ' Brick-earth ', now
utilized for a special class of brick (' sand-stocks '), as opposed to the ordinary
poor bricks of Oxford Clay still made from the clay of the 40 ft. deep pit.
This ' Terrace ' is a sand-bank pure and simple, and it affords the clue to

1 Pocock, loc. cit., p. 87.

2 A cutting in the main road, New Hinksey (1922), which is exactly level with the river tow-
path, showed this gravel 20 ft. deep over the Oxford Clay.

22 Plant-life of the Oxford District

the City-area, as it also presents the first indication of human occupation of
the land. It may thus be regarded as the original precursor of Oxford
City in Palaeolithic times; though the siie is still beyond the building area
of Summertown.

The base of the terrace is of gravel and larger material with drift pebbles,
among which flint implements are found casually in pot-holes on the surface
of the subjacent Oxford Clay. The 'Brick-earth' consists of 'a mild clay'
with a large admixture of fine quartz-sand, with no lime in the upper layers,
probably brought across from the denuded top of Wytham Hill, and closely
similar to the ' Greensand ' at present found on Cumnor Hurst. The brown iron-
coloured sand lies some 20 ft. deep in places, thinning out over the surface
of hummocked Oxford Clay. This sand-bank represents the first land exposed
in the centre of the Oxford valley, and the long bank of very uniform ordinary
gravel of the ' Second ' Terrace subsequently grew southward in the middle
line between Wytham and Elsfield. At the edge of the bank the pure brick-
earth is mixed with minor layers of clean sand, blue clay, and gravel, as the
changing debris of the river-current. The upper surface is also deeply pot-
holed, and a few implements of later date have been found in these depressions.
The top of the brick-earth is now covered by some 2 ft. of soil de'bris with
small pebbles, etc., expressing the drift and accumulation of forest-land on the
gravel substratum over the top of the low hill (230 ft. only) ; though the surface
is now cleared, and from arable and pasture land, is chiefly utilized as golf-course
and cemetery.

The flint-implements found in considerable number, considering the small
area at present excavated, are not necessarily water-borne for any considerable
distance, since they could only have come from higher up the hills, and may
have been dropped in situ^ They may have been washed into pot-holes ; but
the point is where did they come from. From the fact that they are found
at the base of the Third Terrace, and also at its surface, but not in the
Brick-earth itself, it would appear sufficiently clear that man was living in
the . vicinity in the milder inter-terrace period before the 'Third' Terrace was
laid down, and again in the mild period following it. In the latter time
probably on the bank itself. In such case there can be little doubt that the
top of the hill became the site of a palaeolithic ' village '. Flaked flints in
quantity suggest long-continued occupation. It will be noted that the hillock
commanded the entire valley, and in flood-time would have been a central
camp of refuge for other animals as well as man. The soil is well-drained,
and water could be always obtained by digging pits to the clay below. The
presence of a thin layer of peat with vegetable remains (Bell) suggests at
one time a backwater accumulating flood-debris. With a valley-swamp, low
sand and gravel banks, the flood running 5 miles wide, any human occupants
must have lived in wattle-huts, gone about in wattle coracles, and probably
lived on wild-fowl ; there was certainly very little else to eat.2
The general plan of the river-system by this time was much as it is now ;
fine alluvial deposits fill the river-bed, with a flood-level broadening out over
flat expanses, about 3 ft. above summer level. Extreme floods, to recent
times, practically fill the old basin, following the contour line very closely ;
though drainage and the improved locking of the river has somewhat

1 Bell (1904), Q. J. Geolog. Soc., p. 120, strongly emphasizes the local origin of the implements
of quarried flint.

a If it is only possible for a family under present conditions of good husbandry to get a living
throughout the year on 30 acres of land ; with no cultivation at all, the area may be possibly as many
square miles. Or the problem may be considered from the standpoint of trying to live over the cold
and wet winter months in the older parts of Bagley Wood, with no tools but a few flint knives. From
this may be inferred the density of the population, and the ages of such elementary occupation. Nor
on the other hand would there have been much feed for Woolly Rhinoceros or Mammoth. Either these
animals were with man summer visitors, or their bones have accumulated in flood-debris at drinking
places over long ages. The fact that the entire river-valley has been cut out 50 feet deeper since the
Third Terrace began, as well as the depression of the entire area, may imply as many thousands of
years, with a flora to all intents identical with that of the present time.

Physical Featiwes 23

lowered the flood-limit. The river runs on a similar gravel bottom several
feet deep over the Oxford Clay. In the flood-meadows the alluvium is
2-3 ft. deep (Osney) over the gravel, and the gravel 8-12 ft. deep over the
clay. The average depth of the stream is 8-10 ft., except where the gravel
has been removed for ballast- purposes. Off the main channel, kept clear for
navigation, and where the current is reduced by locks, mud accumulates
over the gravel as a nidus for many aquatic plants ; but the clearest stretches
show plants rooted in the gravel. The minor tributary streams (Bullingdon
Brook), blocked with vegetation as the water is reduced in volume, give
peaty bottoms from decomposing aquatics (rather than from Sphagnum}.
As the gravel bed (10-20 ft.) of the Thames at Tilbury is 70 ft. below sea-
level, on Chalk, it is probable that the entire valley has subsided 50-100 ft.
since the Terrace Period.

Soils.

The peculiar shapelessness of the political county of Oxfordshire suffi-
ciently indicates the failure of the ' county ' idea as applied to any general
account of its flora, and this is the more intensified in the case of the Oxford
district, half of which is across the river and labelled Berkshire ; while it is
only 7 miles across (NE.) to Buckinghamshire. Similarly the Oxford Valley
is by no means typical for Oxfordshire, which is made up of bare higher
ground of the Cotswolds to the N W., and of chalk ranges of the Chilterns to
the SE., any more than it is for the predominant chalk ranges of Berkshire.1

The county extends over a long series of outcrops of geological forma-
tion, as Chalk, Upper Greensand, Gault, Lower Greensand, Kimeridge Clay,
Corallian Limestone and sands, Oxford Clay, Cornbrash, Great Oolite,
Middle Lias, &c., of which the Oxford Valley takes only the central members,
as a general mixture of clays and calcareous soils, again so blended by
surface-denudation, the washing of upper strata over the surface of lower,
and the great mass of alluvial drift as gravels and clay silt, quite apart from
the nature of the basal geological formation, that the latter becomes rela-
tively secondary.2

As a rule the Alluvium is mainly under grass. Valley gravels give
arable land, and ploughed patches of fields apparently on the alluvium
(South Hinksey, Binsey) indicate terrace-gravel. The clays, being heavy to
work and cold, are again mainly devoted to poor grassland ; or as in Bagley
Wood, to trees. The Corallian rocks are predominantly indicated by arable
land, as also the Lower Greensand and Shotover Sands, with the Portland
Beds and Calcareous Grit. The Coral Rag of Littlemore and Sandford,
Cowley, Headington and Beckley, gives the best cultivated land. The
woodland flora, however, being more dependent on humus and water-
content, shows little variation in woods on clay or on Corallian formation.

Lime is conspicuously deficient in Plateau Gravels, and in the more
sandy soils of hill-tops, from which it has leached out ; especially in the case
of the Lower Greensand of hills, Shotover Sand, Portland Beds, and much
of the Calcareous Grit. The river gravels of the Terraces, again, are mainly
limestone, lime from which leaches out over the Oxford Clay. The alluvium
contains a large percentage of organic matter, the more so, in the peaty
bottoms of minor streams (Bullingdon Brook, Headington Wick).3 A few

1 County Floras, arranged according to the Natural System, in which also the political area was
subdivided by physical features of river-areas, came in with the Flora of Middlesex, intended as
a London handbook, by Trimen and Dyer (1839). This ^as proved a facile but disappointing
method of dealing with partial floras.

2 Orr and Morison (1916), Agriculture in Oxfordshire, Soils, p. 171. Parts of Bagley Wood
give a soil with 30 per cent, coarse quartz sand, free from lime, of the Boar's Hill Lower Greensand
type, mixed with fine clay and pebble drift over Kimeridge clay.

3 Considerable deposits of peat appear to have been exhausted in search ot cheap fuel, in the

24 Plant-life of the Oxford District

characteristic ' calcicolous ' plants are found only in exposures of Coral
Rag.1

The Modern River- System.

There is no reason to suppose that, during the known historical epoch of
1,000 years, there has been the slightest permanent change in the general
physical conditions of the climate or general topography of the district ; 2
and this fact has a suggestive bearing on the length of time included in
geological periods involving factors still in operation. Minor alterations
have been effected in the drainage system, and roads have made it more
accessible, but in biological essentials the district remains the same. The
alluvial plain is well irrigated by the branches of the Upper Thames (Isis)
and its tributary the Cherwell, both bringing water from outside the restricted
area considered ; the latter joining the Isis below the town at the Barges,
and by the artificial ' New Cut ', formed after the heavy flood of 1882, and
replacing an older channel a little farther down stream. Though carrying
down a considerable quantity of water in the course of the year, these rivers are
little more than shallow broad ditches, which in exceptional summers might
run wholly dry,3 as undoubtedly they often did in the past. The summer
delivery of the Isis has been estimated at 73 million gallons per day,4 and
the winter delivery as 320 millions. The City of Oxford requires about two
million gallons a day as water-supply, this being taken from the Isis above
the town near King's Weir.

The Isis, flowing north at Stanton Harcourt from its junction with the
Windrush, breaks away to the east at Eynsham, picking up the Evenlode,
and rounds Wytham Hill to enter the old valley of the Cherwell, 2 miles
from the present stream at Oxey Mead, and turning sharply SSE. at King's
Weir it enters the Oxford valley from the NW. The main stream passes
Godstow and Port Meadow to Medley Weir and Osney Lock, through the
lower part of the city to Folly Bridge, Iffley, and Sandford. A loop of the
stream, breaking off at Hagley Pool, runs fairly parallel through Wytham,
Ferry Hinksey, and Botley. Collaterals and cross-connexions supply mill-
streams at Botley, Osney, and City Mills, and all these ramifications unite
below the town. With the junction of the Hinksey stream below Iffley, the
river is finally collected in a narrower channel before Sandford and Radley,
when it again turns west to Abingdon. This great lo-mile sweep of the
Thames, the broad areas of alluvial meadowland, and the meandering course
of the Cherwell with its own alluvium (NE.), constitute the more obvious
features of the river-system. The network of streams west of the city is
indicated by the fact that the road from the Castle to Botley, over a stretch
of alluvium a mile wide, formerly crossed 6-7 water-courses. The original
water-system has been increased by a canal to Birmingham (Oxford Canal
1769, completed 1790), running from the Castle Wharf north past Wolvercote,

valley of the Bullingdon Brook (Cowley), and the Bayswater Brook and its connexions (Headington
Wick, Elsfield). Plot (1705), p. 65, clearly describes the cutting and drying of Peats, in one case
from a 4ft. seam. Sibthorp (1794), Flora Oxoniensis, describes Sphagnum as still growing 'in
Peat Bogs on Bullington Green '. Special interest also attaches to a seam of Lignite (4 in.) at
Kidlington, described by Plot (p. 66, loc. cit.), as indicating how the plant-remains of the soil-surface
have been already hunted through and exploited. The organic content of such alluvial soils may be
considerable, and requires to be examined for different areas and depths: e.g., samples dried at
100° C. gave — Bullingdon Bog Valley, mole-casting, 21-52 per cent. Iffley Lock Field, mole-
casting, 21.12 per cent, (taken near the ditch, an old water-course). Cherwell alluvium, surface-soil
of hay-field, 77 per cent. (W. R. Day).

1 Carduus nutans, Cirsium eriopkorum, C. acaule, Helianthemnm vulgare.

2 The frost of Dec. 1142 was probably no more severe than that of March 1895, and the con-
dition of the water-meadows, particularly above Wolvercote, is much the same as at the time of the
Domesday Book.

• s In August 1893 the bed of the river was dry at Folly Bridge, and the steamers ceased to run ;
in 1921 the Cherwell was dry in places, stagnant for miles, with green mantle of Lemna.
4 Prestwich (1876), Water-supply of Oxford, p. 39.

Physical features 25

and connected with the river-system at Duke's Lock. The country to the
east is drained by minor streams as Bayswater Brook, Northfield Brook,
Bullingdon Brook, the channels of which are cut as deep trenches 6-12 ft.
deep, and as many wide. These may carry a full stream in flood*time, on
impervious clays ; but are dry or dwindle to the merest runnels in extreme
dry summers (1921).

The I sis Lock-system. For purposes of navigation, more particularly
by barge, the Thames is held up throughout its course to the sea at 47 locks
and weirs, of which 6 fall within the Oxford district (King's Weir, Godstow
Lock, Medley Weir, Osney, Iffley, and Sandford Locks). A collateral branch
of the Isis, taking off just above King's Weir, and rounding Pixey Mead to
Wolvercote Bridge, is uncontrolled, as is also the Hinksey stream taking off
at Hagley Pool, and running past Wytham : the latter is connected with an
extensive system of ditches in the alluvial area below the town, joining up
again with the main river at the Railway Bridge below Iffley. Even after
locking, the river, though liable to be blocked and banked up by weeds,
also tended to run out in summer, and barges might lie up for 3-4 weeks.1
The lock-system was initiated in the reign of James I, and the mechanism
remains much the same to the present day.2 The first barge, following the
completion of the lock at Iffley, reached Oxford in August, 1635.

The navigable stream is seldom more than loft, deep, except where
gravel has been taken out, leaving deep pits (Old Stream, Cold Arbour,
and Isis at ' The Gut ') ; a depth of 5 ft. in the channel is sufficient for
navigation, a minimum of 3 ft. 9 in. being maintained above Iffley. The
object of the Lock-system is to maintain the water at each lock at a maximum
level (' Head Water '), a datum-line marked empirically for each lock, as the
highest level to which the water can be kept without unduly flooding the
land above. The distances above sea-level are : —

King's Weir . . . (H.W.) 193-55 ft. miles between

Godstow .... 191-02 i-io

Medley .... 187-31 1-48

Osney .... 185-89 -99

Iffley 179-72 2-40

Sandford .... 176-92 1-38.

The total distance from King's Weir to Sandford is 7-3- miles, the fall
14-10 ft, and the average gradient 2-25 ft. per mile. Tail-water at the lock-
gates also gives empirical data based on the requirements of navigation, and
records of such data are taken by the Thames Conservancy three times
a day ; so that the Thames is one of the best observed rivers in the
country.

The total rainfall of the Thames basin normally ranges between
21-32 inches (1887) and 40-87 (1903), the average of 36 years (1883-
1918) being 28-32. The Oxford data (Magdalen Laboratory) give 25-16,
and the Radcliffe Observatory 26-02. Of this fall, less than half finds its
way into the river-system, or 40-3 % in the winter months, and some 21-5 %
during the summer ; the larger proportion being returned to the atmosphere
by evaporation and transpiration ; while there remains a certain leakage
in the form of subterranean streams which also pass beyond the local area.
Or, for 28-3 inches (average) of rain per annum, only 31-8 % (varying 19-44),

1 Plot (1705) p. 239 (the text being written, first edit., 1675); p. 29, 'Our Watermen here in
these shallow Rivers, praying not so much for Rain to fill them when low, as that Weeds may also
grow to help to keep the Waters when they have them, which will otherwise too soon glide away to
their no small detriment.'

2 Plot, loc. cit., p. 238, described in considerable detail. The original 'Lock', with rimers and
keys worked by levers, is seen at Medley, with only a slight fall. What is commonly termed a
'lock', with a double set of gates turned by a beam, was originally a 'turnpike'.

26 Plant-life of the Oxford District

or the equivalent of 9 inches (varying 4-16) is accounted for by the river-
system. This leaves an approximate average of less than 1 8 inches per annum
to supply plant-life ; the suggestion being that an annual rainfall of 18 inches
would be sufficient for the vegetation of the district, if the river did not run
off more at Sand ford than at King's Weir.1

Springs and Brooks. Apart from the main river-system of the Thames
and its backwaters, canals and tributaries (Cherwell, Ray, Evenlode, Wind-
rush, Thame), local conditions of water-supply including small streams and
swamp-areas are more conspicuously dependent on actual rainfall and the
relation of this to percolation through the soil, and the capacity of the latter
for penetration and retention. The geological formation is peculiarly
favourable for the throwing out of springs at all levels. As previously
indicated, the basal formation of the Oxford Valley is a deep bed of Oxford
Clay, which is apparently wholly impervious throughout the greater
proportion of its depth. In this clay the present river-system has been
eroded over the greater part of the district, the valley being covered with
a sheet of alluvium to the limit of older winter-floods, while patches of
gravel of older river-terraces are left as irregular deposits and the debris of
torrential water-courses. These latter are freely permeable as collecting
areas, and water may be thrown out at any outcrop of the clay, at levels
corresponding to the gravel deposit on an old clay bottom, at 300 ft. or more
elevation. Over the clay, patches of residual beds of Corallian strata of
limestones and sands, again more freely pervious, cover wide areas (as at
Headington, Cowley, Littlemore, Tubney) with Coral Rag on hill-slopes
and broad undulating areas (Hinksey, Headington, Cumnor, Stow Wood).
At the exposed junction of these strata with Oxford Clay on the slopes of
the hills (Cumnor, Headington, Wytham, Elsfield) springs are thrown out in
large numbers, giving streams cutting deeply through to the clay-bottom
(Hinksey, Headington Wick, Bullingdon Bog), all tending to feed the main
river-system, and also forming characteristic swampy patches on the clay
sides of the slopes by producing Juncus, Phragmites, and Equisetum
associations, at elevations of 300 ft. or so nearer the city, as a second series
of springs.

Over these more pervious rocks, broad tracts of Kimeridge Clay con-
stitute another more or less impervious layer, more particularly on the
Western side of the district, as iii areas of Bagley Wood, Boar's Hill,
Sunningwell. Locally, again, on the surrounding hills the Kimeridge Clay-
is capped by highly pervious patches of Greensand (Cumnor Hurst, Boar's
Hill), Portland Beds, and Shotover Sands (Shotover, Garsington, Baldon),
so that water percolating through these beds is largely thrown out in
surface-springs at the junction with the Kimeridge Clay, at a higher level of
about 400 ft.,2 giving an upper zone of springs, and again formation of
Hill-swamps of Equisetum, Phragmites^ and Typha> with Juncetum at this
higher elevation. Patches of Plateau Gravel over Kimeridge Clay (Bagley), or
over Gault Clay (Baldon), also assist in giving rise to similar high-level springs,
and affording the water-supply of the population of these areas. Swampy
ground with Mosses and Juncetum may obtain at any elevation, giving Juncus
where most exposed, Equisetum Telmateia, in vast abundance in hollows or
on Hill-slopes (N. Hinksey), 7ypha in standing pools (Chawley), with dense
thorn-scrub in neglected tracts (Chawley Hurst, Headington Quarry). ^

All such streams cut deep hollows in the steep hill-sides, as indicated

1 In 1921, with extreme drought and rainfall 13-14 in. only, the Thames Valley used all the
water falling on it. The Weir-steps were dry at Teddington in Aug. and Sept., and a man crossed
the river at the Weir pool (in waders). Vegetation obviously drew on deeper reserves in the ground,
and was very insufficiently supplied by rain and stream.

2 Horspath, Chilswell.

Physical Features 27

by the grooves in the contour-lines of the map, but are now running
brooks of no great size, apt to dry up in hot summers, or left as mere
runnels and ditches along the sides of fields, uniting to form such streams
as the Bullingdon Brook, Bayswater Brook (Cherwell), Hinksey streams,
Northfield Brook (Isis), Baldon Brook, Holton Brook (Thame), which may
also run in considerable volume in times of winter flood, but in summer
months are almost negligible.

Flood : One of the most spectacular features of the Oxford Valley
is its tendency to flood at any time in the winter months. Both the
Thames and the Cherwell bring water from beyond the district ; the winter
delivery of the Thames is several times that of the summer months, thus
filling the channel. When wastage of evaporation and transpiration of
vegetation is checked, and the average monthly rainfall increased, water
tends to accumulate, the more as the predominant clays are impervious ;
and on the alluvial flats the water runs off with difficulty. The control
of the main stream of the Isis for purposes of navigation pinches the stream
at locks and weirs, older water-courses may become filled up, and water
may be intentionally held up in the upper reaches of the river in order
to reduce the excessive flooding of tracts farther down stream. Though
filling the alluvial basin in older times, improved control of the stream
by deepening the channel and the regulation of weirs has considerably
lessened both the extent and the duration of the flood, and further diminu-
tion is probable ; but when Port Meadow, Osney Fields, Iffley Fields, and
the Cherwell Meadows are under water, the aspect of the country returns
to its primary winter condition, with hamlets spaced along the flood-margin
and the town on its gravel bank, appearing from the surrounding hills as
more or less isolated in a broad lake.

Above the locks flooding follows as soon as the stream runs much over
Head Water, and below the locks where the land is exposed to the delivery
of uncontrolled streams. The meadows below Iffley flood from ' The Weirs *
and the Hinksey Stream ; Osney fields from the Wytham stream, and Port
Meadow from Medley and the mill-stream above Godstow. Medley Weir is
wholly drawn in winter flood : Osney and Sandford Weirs were reconstructed
1884 : Iffley Weir is in process of reconstruction (1922).

The last great flood (Nov. 1894) was the expression of excessive autumnal

rainfall. Floods at the melting of the snow in spring are less usual (Feb. 1 900).

More rarely excessive rainfall may produce floods in May and June (1903).

Medley Weir was wholly drawn, and meadows of the Upper Cherwell under

water in August 1922. The record flood of 1894, at Iffley Lock, rose to

a maximum of 2 ft. 9 in. above Head Water, or 9 in. over the lock-edge and

towpath. Tail-water 9 ft. implies up to 3 ft. over the lower meadows for a wide area.

Ecologically the flood, as falling within the period of winter-peren-

nation, is now of minor importance, and tends to be less the more it is

subject to control. A rushing torrent of water scours the bottom and sides

of the stream, washing out rhizomes of Nuphar, Acortts, Sparganium, etc. ;

these with quantities of stems, fruits and seeds of aquatics and subaquatics

may be left as the water recedes as a conspicuous debris-line, extending

in special cases (as above the locks) to the margin of the old alluvium.

Spring floods may do considerable damage to crops in allotment-areas

(Osney), and to the hay-harvest (June, 1903) ; the water rising after the

grass was cut, and the crop left to blacken on the ground (Iffley fields).

In Aug. 1 92 2 the field below the lock was cut with 2 inches of water standing

in the bottom grass. The relation of the pasture flora to flood -distribution

(e. g. Rumex, sp.) is open to investigation, as also the amount of silt in the

flood-water as determining the fertility of the flood-meadows : but the

general tendency is to eliminate all flooding as much as possible.

28 Plant-life of the Oxford District

III. PRIMARY WOODLAND AND ITS DERIVATIVES

What we are accustomed to call a tree is the typical plant of the
modern land-surface, representing the response of plant-life to conditions of
subaerial environment over a period of hundreds if not thousands of millions
of years. Such trees, again, have not been created or evolved to suit the
conditions of the land alone, but are essentially derivative and migrant to
the land from an older order of submarine existence as seaweeds. Just, in
fact, as man has persistently felt himself to be a stranger and sojourner on
this world, because his body, being inherited in all essentials of structure,
metabolism, and sense-organs from the oceanic Fish, is equally far from
being constructed to suit subaerial conditions. That is to say, in the modern
tree one sees the finished article of long ages of an evolution as long as our
own, going back to the sea where all life as we know it began.

Given an autotrophic plant-organization, of branching shoot-system
displaying photosynthetic laminae to air and incident light, growing-points
with permanent meristem, and a system of secondary increase adding
effective mechanical strength to resist the physical chances and movements
of the medium, — it is evident that, under optimum conditions of tempera-
ture and light-supply, vegetation will continue to increase indefinitely on the
area occupied, and be, in fact, practically immortal, since without senile
decay. Ail these growth-factors having been evolved during submarine
existence, the translation of plant-life to the land-surface does little more at
first than continue such organization, and progressively adapt it to sub-
aerial conditions.

Where conditions of sunlight, temperature, and the necessary water-
supply, are at a maximum, plant-life is still dominant^ and at its
optimum. Thus tropical evergreen rain-forest is not only the primary
station for higher plant-life on the land, but it is still constituted by the
most highly specialized types of tree-vegetation, as a massed jungle of
dominant and competitive plant-forms.1 Where the ground is fully
occupied, such tree-growths can only obtain pre-eminence by outstripping
their fellows in height. Hence upward extension is exaggerated in com-
petition for favourable light-supply, which is a constant taking the year
round. In the struggle to rise higher over adjacent competitors the
arboreal form attains its full differentiation as ' high-forest ' in ' close
canopy '. . Simultaneously with extension to higher levels of the atmo-
sphere (100-300 ft.), the massive trunk is evolved in response to the
demand for resisting lateral displacement by the wind, and the effective
support of the mass of the branches and foliage.

Such a generalized arboreal phase of plant-life is sufficiently familiar
as a commonplace to the inhabitants of even this part of the world's
surface, in the forms of indigenous woodland. For this the biological
conditions require to be more clearly expressed, and the limitations of such
a phase of vegetation more particularly defined. The actual amount of
plant-life in aggregate mass possible on a given area is dependent on such
factors as: — (i) the amount of solar energy falling on unit-area; (2) the
amount of water available in the soil ; (3) the constitution of the substratum in
relation to the supply of food-ions in solution ; (4) the possibilities of seasonal
change including effects of frost, drought, and storm. For example, in
the general case of a suitable soil with sufficient mineral matter, particularly
nitrogen and phosphorus-content in addition to the humus-remains of past

1 Schimper (1903^ Plant-Geography, Eng. Trans., p. 304.

Primary Woodland and its Derivatives 29

generations of vegetation, the essential factors may be considered as : —
(i) the amount of available sunshine in the year as affecting the working
energy ; (2) the degree of temperature as affecting the rate of metabolism ;
(3) the available water-supply which will include all inorganic food-
substances. In the case of primary rain-forest in the tropics, these factors
may be all at an optimum ; but as different cases arise introducing new
problems, when such factors fail individually or collectively, new types of
vegetation are isolated as solving them more or less effectively. Thus in
tropical forest with light and temperature at a maximum, plant-life can rise
to the limit of these physical opportunities ; but water-supply is the deter-
mining factor. With diminished water-supply, the forest-growth fails, trees
loosen canopy, may shed their leaves, present a seasonal response to alter-
nation of wet and dry periods, and become dry deciduous forest, grading to
fewer and fewer trees, and these with highly xerophytic adaptations for
perennation over the dry spell.1

With extension to extra-tropical regions (latitudinal), as northward,
light-supply is reduced, implying less work done in the year ; temperature
also reduces to the limit of frost and snow, further lowering the rate of
metabolism. Trees, again, present reducing features, but water-supply
remains the essential factor in determining the forest-growth, and so long as
it is available canopy may be maintained.

Similarly altitudinal extension on tropical mountain ranges, with a
limit at the snow-line, gives all effects of reduced temperature, but with
undiminished insolation ; and so long as water-supply is effective the trees
persist.

Combination of the case of the deciduous forest passing northward,
and of that on mountain ranges, gives the general case of northward
migration of the trees of the indigenous flora ; all with markedly reduced
habit and reduced annual output, as the highly specialized end-terms of older
phyla of a former tropical existence, now represented by predominantly
deciduous types, working with a short season, and enduring the cold of the
northern winter (frost-period), with the last relics on the northern mountains,
suffering from all disadvantages at the limit of tree-life (Salix, Betula) ; but
within the range of this country, still sufficing to give continuous forest-
formation, so long as soil is available and the water-supply permanent.2

From such general considerations it follows that, coming as it does
within the zone of North Temperate deciduous forest, with full water-supply
throughout the year, the entire area of the Oxford district was originally
general woodland. The tree-types are now comparatively few, as the
migrants of N. Europe, in turn the strays and residual forms of older and
more tropical series. Oak (Quercus pedunculata) is the predominant type, as
the species (with allied Q. sessiliflora) farthest north of a forest-race of trees
still culminating on the forest-ranges of tropical mountains of S. Asia,3 and
passing north at lofty elevation (i-z miles) on the Himalaya ; similarly
associated in Hill Forest with Alnusy Betula, Corylus, Carpinus, Fagus^
Salix, Populus, as comparable residual types also passing farthest north of
their series. Many of these are isolated generic monotypes, flowering in
early spring in order to get seed matured within the year. Much the same
applies to Ulmus montana and Fraxinus, as the last northern strays of
essentially tropical families ; in a lesser degree to Acer campestre ; while
Tilia^ also a residual stray, and alien Castanea, still manage to produce
some seed though only flowering at midsummer.

1 Schimper, loc. cit., p. 351.

2 Tansley (1911), Types of British Vegetation, p. 65.

3 Cf. Wallich (1830), Plantae Asiaticae Rariores, fig. 46, Quercus spicata with erect fruiting-
spike, i ft. long, with over 100 acorns.

30 Plant-life of the Oxford District

The number of locally indigenous trees of high forest, as opposed to
smaller forms of underwood, maintaining their position by natural reproduc-
tion, is extremely limited ; possibly only half a dozen, as : — Oak, Ash, Wych
Elm, Alder, Birch, Hornbeam, and not all of these are seen locally freely
germinating from seed (Oak, Ash, Birch). Other large and familiar tree-
forms are of comparatively recent introduction, and imperfectly naturalized ;
that is to say, always planted. Some of these may produce quantities of
good seed (Sycamore, Horse-Chestnut, Walnut), others do not seed at all,
or only rarely (Common Elm, Plane, Lombardy Poplar, Black Italian
Poplar, Grey Poplar, many Willows). The same applies to the case of
Conifers : Pinus sylvestris was indigenous, but is now only grown by plant-
ing, as also is Taxus. Spruce (Picea excelsa) and Larch (Larix eiiropaea] of
Central Europe, may be largely planted, but do not always mature seed.
Cedars rarely do so. These again are Northern Conifers still attempting to
mature seed in one season, a problem solved more successfully by Pinus t
which goes farthest north, by taking two. In dealing with introduced forms,
it must be noted that it is not so much a question of the successful growth
of the individual, which determines its success as an ecological constituent of
the flora, as its capacity for producing fertile seed, and ability to grow from
such seed in competition with other plants. Failure in seed-maturation, or
restriction of fertile seeds below the amount required to counter-balance the
normal wastage of the reproductive mechanism, is fatal to the race, and is
the direct effect of a shortened working season with enfeebled light-supply,
or lack of adjustment of the inherited periodicity of the plant to that of the
climate.

Confirmation of such deductions as to the original forest-flora may be
seen in the phenomena of regression of cultivated land and pastures, when
left derelict, to their original condition. Thus thorn-scrub (c thicket ') gives
place ultimately to woodland trees, as Ash and Oak in good ground, and in
the water-meadows Salix (sp.), Alnus, Fraxinus, and Populus grow freely
in ditches and hedge-rows. In a short period the entire district would
revert to general woodland, and there can be no doubt that the original
state of the country was that of the general forest of the central plain of
England, much as first described in literature by Caesar, and left largely
uncleared to the coming of the English, as locally a broad tract of swamp-
forest, penetrated by water-courses, above which low wooded-hills emerged ;
the lower ground affording a tangled mass of vegetation, only swept clear
by winter-floods, to which the land would soon revert if left vacant of human
occupation.

By Neolithic man with a few domesticated animals, hill-clearings were
made by fire, and valley-clearings similarly afforded pasture for sheep and
cattle. The introduction of cattle implies the simultaneous introduction of
many weeds and grasses of pasture-land, now passing as indigenous, but not
found in woodland-clearings. But casual grazing will not keep land from
regressing to scrub: constant firing was undoubtedly the oldest method of
keeping the woodland in check, as it is still employed to keep down Gorse
and Bracken, regressive thorn-scrub and brambles. Only in later times does
the use of the scythe effectively produce the permanent pasture of grass-lands
by annual mowings.

The first English settlers cleared the whole of the level alluvial tract, more
or less submerged in winter-months, as grazing-land for their cattle fed in
winter by the hay-crop, to the beginning of the rising ground. The latter
they tilled for their own food-supply as corn; and cultivation spread up the
low slopes of the hills, leaving the tops still covered with wooded caps, and
the valley-slopes dotted with small holdings. The complete clearing of the
alluvial flats as water-meadows, was the essential factor in the colonization of

Primary Woodland and its Derivatives 31

the neighbourhood, as ultimately of the subsequent progression of the city.
These meadows are retained to the present day, as their liability to flooding
in winter, and exceptionally even in early summer, precludes their utilization
for any other purpose, until the level can be raised (cf. Port Meadow and Osney
allotments).

Further diminution of the wooded-area followed increasing local and urban
demands for fuel. Small copses were retained in the agricultural area. Derelict
land, too wet on a clay bottom, too dry on upper clay, or too steep on hill-sides,
was left to such woodland as it might carry. Broader areas of woodland, long
retained as common land, have been enclosed, and now little remains of the
original general forest-formation save tracts more or less 'forested' or 'pre-
served', as Bagley Wood, Wytham Wood, Stow Wood, and a multitude of
minor copses, as marked scattered on the map. The tops of adjacent hills
have been largely cleared, although all appear capable of carrying woodland.
Cumnor Hurst has been cleared by fire, Shotover mainly by cultivation ; the
only suggestively dry hill-tract is the northern end of Garsington Hill, now
under arable land, with but few trees in the hedges.

Residual Woodland, in whatever condition it may have been forested, on
land which has apparently never known the plough, may be traced on Oxford
Clay in Marley Wood, Wytham, Studley, Stanton St. John, Noke Wood,
Water Perry, and Headington Wick; on Kimeridge Clay in Bagley Wood,
Sandford Brake, Brasenose Wood ; on Greensand in Hen Wood ; on Calcareous
Grit in Tubney Wood and Stow Wood.

Origin of Underwood : In high tropical forest of primal order there is
no underwood. The canopy is dense, the lofty trees may be wreathed with
liana climbers, and gay with high zones of epiphytes, but the ground is bare.1
Following the extension of forest to dry and extra-tropical regions with
reduced or seasonal water-supply, the canopy is thinned, and increased
competition for water leads to the relegation of many arboreal forms to a
lower zone of underwood, as smaller trees, still woody and arboreal in habit,
but scarcely worthy of the name of timber-tree, in all degrees of diameter and
size of woody stem, to the smallest woody shrubs in the poorer classes of
forest. This production of smaller, apparently dwarfed forms, is, however,
not entirely a phenomenon of reduction, or mere deterioration of vegetative
habit. The latter somatic feature is correlated with an advance in repro-
ductive specialization, as these small trees flower and fruit at an earlier
stage, giving quicker returns, and so have no need to attain the full size of
the older type of tree. It is clear that this idea carried to excess, will
give smaller shrubs which may even flower the first year of their growth,
and continue to flower and fruit for many succeeding years. Few trees of
high forest do this ; the age-limit for flowering being largely determined
by the fact that the bulky soma with great root-penetration, at last reaches
the limit of balancing its proteid -synthesis with its photosynthetic capacity,
beyond which excess carbohydrate becomes a nuisance, and may be elimi-
nated in spore-production and the seed-stage. In such case, trees may be
said to reach a certain adult phase ; comparatively little growth is added
once the fruiting-period is reached, and parasitic seed-stages drain the parent
organism of superfluous material. A period of 30-50 years is commonly
required by forest -trees to reach this point, and it is evident that any gain on
such a time-limit will prove advantageous in hastening on the race.

Such small trees and bush-forms become relatively more numerous as
the high forest deteriorates ; and hence in northern woods will be abundant.
They constitute a characteristic feature of English woodland ; the more so
as the flowers may be conspicuous - and decorative as insect-pollinated
mechanisms of considerable elaboration, or the fruits are gaily coloured and

1 Schimper (1903), loc. cit.3 pp. 288, 298, 301.

32 Plant-life of the Oxford District

bird-dispersed. So far, it will be noticed that the great majority of indig-
enous trees of high-forest are anemophilous (Oak, Beech, Alder), and bear
wind-dispersed seeds (Ash, Poplar, Hornbeam, /V««j) : Ulmus and Castanea
retain inferior insect-pollinated mechanisms, but may fall back on wind :
Tilia, Acer Pseudoplatanus, Aesculus, are later introductions producing bee-
pollinated flowers. Many forest-types characteristic of the deteriorated
woodland of this country are really underwood forms (Hornbeam, Acer
campestre, Hazel, Salix caprea, Holly, Hawthorn), and it is difficult to draw
any very exact line.

As the more characteristic types of underwood may be taken :

Crataegus monogyna (Hawthorn). Cornus sanguinea (Dogwood).

Pyrus Aucuparia (Mountain Ash). Salix caprea (Broad-leaved Sallow).

Euonymus europaeus (Spindle Tree). Salix cinerea (Sallow).

Prunus spinosa (Blackthorn). Hedera Helix (Ivy).

Pyrus Malus (Crab-apple). Clematis Vitalba.

Ligustrum vulgare (Privet). Lonicera Periclymenum (Honeysuckle).

Ilex Aquifolium (Holly). Viscum album (Mistletoe).

Sambucus nigra (Elder). Rhamnus catharticus (Buckthorn).

Viburnum Lantana (Wayfaring Tree). Rosa canina (Dog Rose).

Viburnum Opulus (Guelder Rose). Rubus fruticosus (Brambles).

All these have insect-pollinated flowers, and (with the exception of
Clematis and Salix) bird-dispersed fruits. The fact that they are con-
spicuous and widely known is indicated by their English appellations, as
familar woodland forms. As aliens of similar grade may be added Sym-
phoricarpus racemosus (Snowberry), Prunus Laurocerasus (Cherry Laurel),
Rhododendron, Buxus, and planted species of Salix, Acer, Crataegus, Pyrus,
Cotoneaster. Similar types, as general favourites in garden cultivation, are
Laburnum, Euonymus japonicus^ Viburnum Tinus, Crataegus Pyracantha,
Spiraea (sp.), Rhus typhina, Syringa vulgaris (Lilac), Weigelia^ Buddleia,
Philadelphiis, etc., as scheduled in florists' catalogues.

Such small trees are rarely more than a foot in diameter (Acer cam-
pestre, Holly, Pyrus Malus), and range to an inch or less (Rosa, Rubus), in
which case new shoots are thrown up with a growth of 1-2 seasons only.
Smaller trees follow similar lines of progression to shrubs and woody under-
growth, including woody lianas and sub-herbaceous climbers. The empirical
criterion of such a shrub-type is taken as one which carries a woody stem,
increasing year by year with a definite cambium giving annual rings of wood.
Other features of somatic deterioration may be contributory causes ; half a
dozen maybe mentioned. The essential feature of the somatic organization
of a tree-type of high forest is its strong vertically growing main axis,
carrying a great leaf-area to incident light, in competition with its fellows.
This involves the co-operation of several distinct mechanisms, as (i) Domi-
nance of the main axis over laterals ; (2) Marked negative geotropism ;
(3) Active cambial increase ; (4) Effective mechanical tissues ; (5) Inter-
calary internodal extension ; (6) Deep-sinking root-system (positively geo-
tropic). Under stress of competition for light, water, and substratum, some
weak point will develop, and plants may fail in any or in all of these respects.
Those falling behind may develop compensatory equipment which may
enable the race to carry on in a feebler condition, or the problem may be
solved in some other way.

Elegant applications of the rule are seen in the progression of under-
wood shrubs and herbaceous plants. With diminution in the dominance of
the main axis, the laterals increase in development, the effect of concentra-
tion on the primary stem is lost, a shrubby bush-habit supervenes, and
the latter may be effective in xeromorphic habit on a smaller scale ( Broom,

JB

o

5

"8"

O

Primary Woodland and its Derivatives 33

Gorse). Loss of negative geotropism tends to production of flexuous shoots,
the prostrate habit, and even to the case of the twining liana utilizing a
compensatory mechanism of transverse geotropism. Reduction of inter-
calary extension gives the dwarf-habit, in the limit the rosette-habit. Of
the common types of woodland, Corylus shows the deteriorated root-system:
Hedera, a climber with weak stem, shows a compensatory development of
adventitious roots : Lonicera is a feebly twining woody liana-form : Clematis,
more effective as a woody liana, climbs by means of irritable leaf-petioles :
Rosa becomes a scrambler by stem-spines : Rubus is even more flexuous, or
prostrate with the shoots freely rooting at the ends. The point is to see
that all plants with such equipment are at bottom forest-tree failures^
making the best of second-rate somatic equipment, which, when compensated
by greater efficiency in reproductive organization (insect-pollination, bird-
dispersal), so lessens the- problem of wastage, that the type as a whole
becomes more highly organized, since continuing to give good results in
more difficult surroundings. However racially specialized, the underwood
tree, the shrub, the liana, and ultimately the herbaceous perennial, have all
been derived by secondary adaptations from a primal forest-tree type ; and
there seems to be no way of escaping this conclusion.1 From another
standpoint all such derivative forms are regarded as deteriorated, so far as
they are less fitted to dominate the stations with optimum conditions, which
called forth their ancestors, though s,uch stations are still available and are
occupied by their more successful contemporaries.

IV. SUBORDINATE AND HERBACEOUS FLORA

It is important to realize that any theory of evolution which records
survival and success, also takes cognizance of decadence and failure ; and
any analysis of the factors making for the former implies an equal necessity
for the consideration of the possibilities and effects of the latter ; as each
such factor may fail individually, or in association with others. In fact,
peculiar sympathy may be said to attach to failure, since every individual
organism which lives on this world is a failure, more or less, since it inevit-
ably dies. But failure in one respect may open up new avenues of pro-
gression in others, and thus the facts of the main evolution of plants under
optimum conditions are open to a wide range of variation and alteration as
the conditions of life are themselves changed. Thus, in a lofty tropical
rain-forest, where all the factors for vegetable growth are at an optimum,
trees compete with one another, and many fail where a few succeed. Beyond
the range of such a forest, with diminished value in the complex of external
conditions, the struggle becomes more intense as the conditions become the
more unfavourable, until the main fight concentrates against the environ-
ment rather than against other organism. As already indicated, the
essential structural factors for tree-dominance, are (i) the specialization of
a mechanically efficient main axis, carrying the weight of the plant-
system, (a) considerable internodal extension, giving height, (3) strong
negative geotropism in the growing apex, maintaining vertical orientation.
Where any, or all of these fail, the arboreal type deteriorates ; e. g., to a
small tree if insufficiently massive ; to a shrub, if the main stem loses its

1 That is to say, it is not so easy to read the story the other way, and to trace the dominance of
the long-lived slowly-maturing tree as the result of the specialization of factors possessed in a
rudimentary condition by the herbaceous perennial ; since the forest-tree is not the most paying
proposition biologically, and some reason has to be given for the initiation of the corresponding
structural characters seen in the smaller plant.

C

34 Plant-life of the Oxford District

leadership ; to a scrambling or prostrate shoot-system, where the negative
geotropism fails. Again, among a mass of competing trees, the primary
struggle is to secure some sort of substratum, implying a connexion with
the soil and its food-salt supply. Failures can only become attached to
other organisms, as (i) Parasites, (a) Epiphytes, (3) Climbers, or (4) live as
Saprophytes on decaying debris at the forest base. Parasites, making
vicarious haustorial connexion with the transpiration-current of their host,
may retain the woody habit. Climbers, utilizing the possibilities of inflor-
escence-tendrils, leaf-tendrils, root-attachment, or a special mechanism of
transverse geotropism giving the twining habit, may remain arboreal to a
limited extent. But Saprophytes^ losing their photosynthetic mechanism
(holosaphrophytes), are never woody, and Epiphytes only acquire the
arboreal habit as their roots reach down to the soil. For example, the
source of essential phosphate for an epiphytic orchid, living possibly 200 ft.
high up on the branch of a tree, must be precarious to the last degree.
Again, in such a closed formation, one wonders what becomes of all the
output of seeds by the dominant trees ; but even in the best regulated forest
there are chances of accident, the largest trees must fail and fall at some
time ; tempest, lightning, and even earthquakes, may have to be reckoned
with. So that even if the entire forest be demolished, provision for imme-
diate regeneration has to be kept in reserve, as a necessary part of the
wastage-problem of the race. Every optimum tropical forest thus carries
its normally associated equipment of such forest-tree failures.

In more open forest, with the introduction of the deciduous habit, and
less favourable conditions for tree-development, reduced shrubs and herba-
ceous forms acquire a new significance ; and the latter, having served so
long an apprenticeship to starvation, may now live and reproduce on the
food-material gained in a shorter season than can a tree. In this way, as
the conditions for tree-growth become more unfavourable, the herbaceous
perennial acquires a greater preponderance in the flora. That is to say,
even the optimum forest must come to an end somewhere ; in space, as the
conditions of soil and temperature change for the worse, and by time-factors,
as seasonal extremes become more and more marked. Hence, though
throughout all the ages, the evolutionary progression of the forest-tree is
the main theme of Botany, there has been always a constant stream of
phyletic debris of such races, which, failing in the full arboreal habit, may
nevertheless make a working-success of some alternative line of existence.
It is, in fact, the special property of the intensive energizing action of
plasmic matter, which we call ' Life ', to respond in the course of time to
every possibility of environmental complex ; and since we, as a human race,
have left the tropical forest-zone, the more inferior types of vegetative
organism, as herbaceous plants which have also lost the arboreal habit
(though in a different sense), appeal to us as more noteworthy in their
solution of the many complex problems of extra-forest land.

Origin of Herbaceous Plants. The case of the plant which never
makes more than the first year's wood, introduces the type which gives the
greatest range of variety in all modern flora, as the one which carries the
principle of quick returns to the seasonal limit of seed-production on special
shoots of one year's growth, followed normally by exhaustion and death of
these axes after fruiting ; perennation being maintained by parts at the
soil-level, or below ground, in a definite rhizome (root-stock) region, which
may itself be even massive and woody, but does not commonly appear above
ground. Such extreme changes may appear within the limits of a con-
ventional genus ; since generic characters are commonly founded on the
reproductive (floral) mechanism, as involving more deeply seated factors of

Subordinate and Herbaceous Flora 35

racial organization. They may be combined with any or all of the pre-
ceding features of somatic reduction observed in deteriorated arboreal forms.
With the loss of the necessity for a rigid axis, mechanically efficient over
many years, the cambial mechanism and that particular type of vascular
structure may be even wholly lost. In the great majority of cases the
herbaceous stem presents only vestigial traces of its former timber-produc-
tion. From the rhizome, or lower portion of the plant, retained at the soil-
level in safe perennation, annual shoots of photosynthetic value, ultimately
flowering and fruiting out, are alone produced ; or the main axis may be
reduced by the loss of intercalary extension to a mere basal * rosette '.

Somatically the herbaceous plant is in essentials only a greatly reduced
and deteriorated version of the original arboreal form from which it came ;
but reproductively it has gained enormously in efficiency. A big body is
after all of no use in itself except as providing a large supply of food-material
on a grand scale. With increased efficiency of floral mechanism, seed-
formation, and seed-dispersal to new ground, the wastage-problem may be
so successfully compensated that such vast spore and seed-output is no
longer requisite. The machine becomes more efficient as more economical.
The more a plant is enabled to withstand the disadvantage of a short
working-season (following reduction of water-supply, light, or temperature),
and the quicker it returns its seed-output, the more highly organized is the
racial mechanism, and the higher the type in the scale of organization.
Evolution measures races against races, not individuals against individuals.

So long as the plant can dominate the environment under optimum
biological conditions, however short they may be in point of time (season-
ally), and endure perennation during an alternating period of stress, the
latter is forgotten in the high degree of activity and specialization of the
former ; just as an organism which sleeps to live with renewed activity on
waking, is regarded as more highly advanced in the scheme of life, than one
which never sleeps because it never works at an intensive rate. The intro-
duction of an intensive time-factor^ as tending to get a move on in evolution,
is the thing which greatly counts.

From this standpoint, the herbaceous perennials of extra-forest zones
represent one of the crowning phases of modern vegetation, and phases of
somatic reduction may be carried to extremes. Absence of cambial increase,
associated with the restriction of stems to annual duration, may end in the
suppression of all vascular construction. Want of mechanical tissue again
leads to a prostrate or creeping habit, which is further emphasized by change
of geotropic response. While omission of intercalary extension may give a
rosette-habit, extreme development of this factor, combined with preceding
reduction-effects, gives the ' runner ' and * stolon ' of the rhizomatous habit.
On the other hand, the fact that all these factors may be retained in the
erected inflorescence and floral axes, shot up as miniature arboreal growths
for the function of flowering and fruiting, indicates that their suppression
in the herbaceous perennial, with a limiting case in the creeping underground
rhizome, is still wholly secondary ; and again implies a very special habit
adapted to the needs of a special type of vegetation, rather than being a
* primitive ' condition.

The special value of the Herbaceous Perennial in the scheme of plant-
life, consists in the fact that it can occupy stations available for some part of
the year, where large trees cannot maintain existence through the extremes
of the seasonal changes. It represents the highly specialized response to
extreme seasonal change, with short working-period, when sunlight and
water-supply may be at an optimum ; hence in the shortened season of a
northern climate, herbaceous representatives of many families compete on

36 Plant-life of the Oxford District

more equal terms with the vestigial tree-types of underwood, as a dense mat
of growth at the forest-base, occupying all available substratum, and taking
the chances of light-supply and water-supply, to ultimately form associations
with the larger growths. Though it is evident that they would do still
better in more favourable stations, if the competing and dominant trees were
removed.

Enduring a wider range of vicissitudes of biological environment, such
herbaceous perennials come into further relation with the associated inten-
sive insect-life of similar seasonal activity ; hence the flowers are predomi-
nantly insect-pollinated, while the seeds are more admirably fitted to with-
stand the rigours of the perennation-period, commonly materialized as
extreme desiccation of extra-forest region, and so tend to acquire a degree
of vitality far beyond that of the older woodland tree — especially those of
damp forest which are not required to dry off at all, and commonly possess
little vitality when once dried (Oak, Walnut, Aesculus, Salix).

Such types constitute the bulk of the Flora of the North Temperate
extra-forest zone, and are largely represented in indigenous flora by many
genera and species, especially of such families as Cruciferae, Caryophyll-
aceae, Ranunculaceae, Leguminosae, Umbelliferae, Labiatae, Scrophulari-
aceae, Compositae, Gramineae, Cyperaceae, as representative families of
Herbaceous attainment. Locally some 500 plants come under this heading
in the wild flora, as well as a great range of forms in field and garden -
cultivation, as the most familiar flowers of arable land and pasture, hedges
and woodland clearings, where vicissitudes of the environment are at a maxi-
mum, and the working-period may be favourable for but 3-3 months in the
year.

Annual Plants and Ephemerals. All the considerations drawn from
the case of the Herbaceous Perennial apply with increased force to the special
case of the herbaceous monocarpic plant which presents the limiting
specialization as response to seasonal effects in the production of the ' mono-
carpic ' habit, with one flowering and fruiting period in the life of the
individual. The soma does not perennate after once fruiting, but dies of
exhaustion in abundant seed-production, with no residual shoots to carry on
growth in a subsequent season. The seed-stage, that is to say, remains all-
sufrlcing for effective perennation, as the seed-stage may be specialized to
withstand the greatest range and duration of desiccation, heat, and cold.
This, however, implies the necessity of open ground for germination, and
the annual is of little value in occupied woodland or a closed formation,
save in clearings or on the death of larger organisms involving subjacent
vegetation in their decay. Beyond the forest-zone annuals stand a good
chance in the immediate occupation of ground in which normal perennials
cannot even perennate, whether from extreme drought or extreme cold. In
such cases early maturity and rapid seed-production alone gives them
superiority over the herbaceous perennial ; as the latter in turn went one
better than the woodland tree. Such monocarpic plants are so far the most
highly organized representatives of the plant-kingdom, running parallel
with the extreme development of the insect- life of the land, in exact response
to the same seasonal range of the yearly period. The annual plant, again,
becomes the type so commonly exploited by man, as giving a crop, which
may be sown, harvested and cleared, with the provision of unoccupied
ground for its successor, in minimum time.1

Variations on the theme occur, as : —

(i) The Ephemeral, for which an even shorter period of optimum con-

1 Cf. 'Ten Week Stocks' of garden cultivation, and a local race of Barley formerly harvested
9-10 weeks from sowing (Plot, 1705, p. 155).

Subordinate and Herbaceous Flora 37

ditions, repeated 2-3 times within the year, may suffice to produce the
seeds of a new generation ; an extreme case characteristic of several common
weeds.

(2) The Biennial^ or two-season plant, in which the short duration of
the annual working-season may be compensated by a perennation-phase
over the first winter, with postponement of the fruiting stage to the second
summer ; affording incidentally an admirable case for exploitation of stored
reserves at the end of the first season.

(3) In more tropical regions, with no frost, but xerophytic endurance
of long-continued drought, such monocarpic plants may extend their work-
ing-period over many short vegetative seasons, and finally fruit out on an
intensive scale ; but no examples of this type occur in indigenous flora, so
that its occasional observation in garden-cultivation (cf. Agave) attracts
attention.

Effective methods of herbaceous perennation, originally the response to
conditions of extreme desiccation over a dry season, may prove equally
efficacious against the extremes of Climate, as expressed in exposure to
cold winds at great elevation, or to the cold and wet of a dark Northern
winter. Hence in a North Temperate climate the herbaceous perennials
of a warmer region, with acquired effective perennation mechanism (especi-
ally in the extreme form of rhizome-extension 1 below the frost level, or by
the attainment of marked annual periodicity) may grow in a short hot
summer in a manner recalling the vegetation of even a tropical aspect. The
latter is the general experience of garden-cultivation in this country (cf.
Helianthus annuus, Zea Mais, Cucurbita Pepo> Ricinus, Nicotiand)\ but
even in indigenous flora the last strays of essentially tropical types may
extend northward as woodland forms, the last representatives of their special
lines, commonly presenting other extreme phases of somatic or biological
organization. Cf. Cuscuta^ holoparasite and annual; Calystegia, the most
sensitive indigenous stem-twiner, rhizomatous ; Bryonia, rhizomatous, and
the most perfect tendril-climber ; Tamus, rhizomatous, and a twining Mono-
cotyledon ; also the last residual Orchids (Platy anther a, moth-pollinated,
Lister a, fly-pollinated) of epiphytic origin.

An interesting case of the water-problem is seen in the herbaceous
Xerophytes which vegetate in early spring to flower during the hottest
period of the year, often with extreme xeromorphic adaptations against loss
of available water, as spinous Thistles, Dipsacus, hairy and glandular Labi-
ates, succulents of walls and stony places (Sedum, Sempervirum)^ as also
the plants of roadsides and waste debris, enduring more concentrated soil-
solutions (Chenopodium alburn^ Polygonum avictdare, and the originally
halophytic Beets and Mangel).

All degrees of complexity obtain, as what is commonly isolated as
apparently a special modification to one end, may more or less satisfactorily
solve several distinct problems ; so that plants cannot be accurately or
mechanically graded. One adaptation may play into others according to
edaphic changes, as well as climatic. A mechanism of perennation, originated
in response to extreme drought, may be equally effective against loss of
absorptive function in cold wet soil. Plants originating as special types of
dry stations with minimum water-supply, may endure swamp-conditions
which imply reduced root-activity. In this way xerophytes may apparently
grow as hygrophytes ; and the latter if they can invent a method of check-
ing excessive transpiration, may be found in xerophytic stations. (Cf. Iris of
sandy deserts and/r& Pseudacorus of the ditch- side ; Polygonum amphibium
flowering as an aquatic, and vegetating in dry sandy pastures ; Eqtdsetum

1 Cf. Hop, Rhubarb, Rumex Hydrolapathum, Bryonia, Asparagus, Calystegia,

38 -Plant-life of the Oxford District

arvense and E. Telmateia of the swamp, also intrusive in pastures, arable
fields and hedges).

Not only may species of the samegemts show range of type from shrub
to herbaceous perennial, or from perennial to biennial or annual, according to
features of somatic organization, or time-factors of the reproductive period,
but in the same genus representative or complementary species commonly
diverge to different biological lines or stations, as xerophytes v. subaquatics,
summer-flowering v. spring-flowering, climbers v. non-climbers, etc. ; since,
as already noted, natural relationship is expressed in the more fundamental
features of racial mechanism traced in the details of the reproductive pro-
cesses, and seen most readily in the floral structures rather than in the
vegetative shoot-system.

To sum up, the general case of the progression of the Herbaceous
Xerophyte is sufficiently familiar, as its response to the necessities of a
short season cuts its working history down to the stage of the biennial,
annual, or even * ephemeral ', or leads to a multiseasonal and monocarpic
habit. The vegetative shoot-construction has lost its woody texture, the
shoot-system is specially adapted to perennate over the dry season in
rosette or rhizome-form. In the limit, the subterranean rhizome, with its
special cases of corms, tubers, and bulbs, affords a familiar example of
getting beneath the surface of the protective soil and stopping there ; while
in the short favourable part of the year the reproductive system may long
tend to repeat, as far as possible, in its inflorescence-axis, the original erect
branching habit of the arboreal prototype. Under these conditions, the
flowers may retain an organization as fully efficient, quite as ' primitive ', or
even more suggestively ' elementary ' and archaic than those of any forest-
tree (cf. Helleborus, Aquilegia, with Magnolia and Liriodendron). The
same mechanism which is effective during heat-perennation, is usually also
efficacious for cold and frost-perennation (especially once well below the
surface of the ground), and the perennation-problem is so far unified. The
active life of the plant, including more especially its reproductive cycle, is
thus condensed within the limit of the favourable growth-period, as deter-
mined more particularly by the possible water-supply.

Given the sunlight and temperature of any part of the world in tropical
to temperate regions, the critical factor in determining the range of forest-
canopy is the question of adequate water-supply, — whether at some time
too little, as expressed in low rainfall, in impervious soil, extreme evapora-
tion, rocky ground, etc., or too much, tending to swamp areas insufficiently
aerated, muddy bottoms with no holding ground, grading to deep and open
water of standing ponds, streams, lakes, and even rivers in which the current
introduces an additional factor. To the former case belong the wide range
of reduced herbaceous types conveniently classed as Xerophytes ; * to the
latter lies open an equally wide scope of adaptation to conditions of aquatic
environment, in which the essential water-problem no longer obtains, though
temperature and light in the end become limiting factors.

Of all such reduced herbaceous flora, adapting their shoot-mechanisms
to these conditions, the rhizomatous type is perhaps the most interesting ;
since with the prostrate habit, and loss of negative geotropism in the vege-
tative shoots, together with the retention of the possibility of intercalary
extension (or even with practically none at all), there remains a definite
mechanism for lateral transportation, which is beyond the power of the
normal ancestral tree. With this capacity for lateral extension and adven-
titious rooting, such types of vegetation can travel in the course of time
considerable distances, with the chance of finding conditions more suit-

1 Schimper (1903), Plant Geography, p. 3.

Subordinate and Herbaceous Flora 39

able for their existence. This same faculty for lateral progression has again
a wide application in the attainment of a gregarious habit; e. g., in oover-
ing soil with a mantle of protective vegetation on the part of xerophytes,
or in travelling towards the source of water in facultative aquatics. All
aquatics have apparently passed through this phase. In all cases the
gregarious habit initiates a new form of canopy, preferably indicated as
a * mantle ' or ' mat '-formation, and the individual organisms acquire
a certain amount of control of their special environment by collective action,
which again puts them on a higher plane.1

The case of the Aquatic is more complex, since the water-problem so
insistent in the general case of the land-plant is largely eliminated ; perenna-
tion is restricted to periods of winter-cold and darkness, only in the limit to the
possibility of the total disappearance of the water. But even in the growing
season temperature is largely regulated by that of the water, which shows
relatively little range, and may be widely different from that of the air ; while
the aeration problem of the submerged portion becomes critical, since the free
oxygen-supply is at best only \ per cent, by volume, as compared with the
ao per cent, of the free atmosphere. No aquatic can make good in the
water until it has solved the problem of aerating the submerged root-system
by which it absorbs its food-salts, by means of an exaggeration of the
system of intercellular spaces, and the retention of the waste O2 of photo-
synthesis. As this method is the best thing the plant can do,2 but is never
wholly a success, the root- system remains permanently handicapped. Its
absorptive capacity is strictly limited, with consequent result on the reduced
transpiration system, as exhibited in the further deterioration of all vascular
tissue, and restricting the supply of essential food-salts. Water-plants
become characteristically starved, pulpy and parenchymatous, with lacunar
tissue, and little mechanical efficiency beyond the maintenance of the
turgidity of the active cell-units with abundant and cheap water-content.

On the other hand, since protoplasm is itself a medium containing
over 90 per cent, water, it is evident that while no effective plant-life can
ever flourish under extreme xerophytic conditions, however intensive it
may be during its short spell of active growth, the aquatic environment is
clearly the original one for all plant-life, and such regression to the water
may open up new possibilities. Since the water-problem, which is after all
the most difficult proposition for all land-flora, is now largely discounted, so
long as the water itself is available, it remains only a matter of difficulty
for the parts which are out of the medium ; and such plants return to the
water armed with their age-long experience as seed-plants of the land, and
are now on a new footing in their old environment.

The case of the Facultative Aquatic, as that of a rhizomatous plant rooted
in the ground, and following failing water-supply, enduring submergence,
or even floating on the surface, but without any special anatomical adapta-
tions for aeration, remains wholly incidental. The story of the Obligate
Aquatic begins with the plant rooted in subaqueous ground, and supplying
oxygen to its root-system from the over-water green shoots. To such
a plant the amount of water present begins to be a secondary consideration.
The vegetative parts grow above the surface to reach air and light, and the
flowering shoots may retain much of their original erect branching habit,
with flowers of primitive or even highly elaborated organization, on a par
with that of the xerophyte of a short season, or of actual forest-trees. In

1 For such possibilities of invasive action by gregarious rhizomatous forms residual from types
of tropical organization, cf. the case of Urtica dioica (Sting Nettle) of the Urticaceae, that of
Mercurialis as the last elementary type of the Euphorbiaceae farthest north, and the remarkable
specialization of Pteris aquilina (Bracken) as the preponderant indigenous fern.

2 Schimper (1903), loc. cit., p. 25.

40 Plant-life of the Oxford District

such rhizomatous forms, once the rhizome-habit has been attained by the
loss of the normal factors of arboreal growth in the main stem, the capacity
for geotropic erection and internodal elongation may be retained to a certain
extent, while the orientation and display of the foliage laminae may be still
the prerogative of the leaf-petioles.

I. Hence the First Phase of the Obligate Aquatic x is that of a herba-
ceous plant, with rhizome rooted in the mud of a woodland swamp-area,
sending up erect leafy axes subsequently to produce flowers and fruits in
free air, in the normal manner of woodland undergrowth, but already charac-
terized by a feebly-absorbing root-system. In damp air the shoot-system
may retain fairly normal construction ; but in more open situations xero-
morphic features begin to be shown, as the leaves tend to lose water faster
than they can take it up ; and shoots with greatly reduced foliage-members
become characteristic. In this respect it is interesting to compare the
limiting reduction of Equisetum (Horsetail) of the Pteridophyta, with its
leaves reduced to merest points, and photosynthesis entirely restricted to
the green shoots, with the Angiosperm Hippuris (Mare's Tail), the latter with
greatly reduced leaves on the subaerial shoots, and minute inconspicuous
flowers : again as expressing the fact that progression in aquatic habit is
by no means a factor of time. A certain level of attainment, once estab-
lished, may be so maintained indefinitely and unchanged, so long as the plant
may so come to occupy an 'inferior' station in which there is little competition.
Equisetum, as the typical aquatic of this category, is at the same time one
of the oldest known types of Land-flora, as a greatly deteriorated representa-
tive of a race that was arboreal as Calamites of the Palaeozoic, and probably
beyond : Hippuris, a seed-plant of the more modern epoch, does not get so
far in shoot-reduction and specialization, though curiously similar in general
dimensions and whorled habit, but other Angiosperms go far further.

II. So long as the shoot-system can elongate above the water-level,
and the roots can obtain free oxygen from the over- water parts, no specially
new problem arises ; but where the stem remains wholly submerged, reduced
to a prostrate dorsiventral rhizome, or bearing terminal rosettes of leaves,
the entire onus of the erection and display of the foliage members in the
air, falls on the leaf-petioles and the leaf-lamina itself. Where again the
rhizomatous plants are closely gregarious, occupying all the substratum
available, lateral extension will be precluded, vertical elongation is the only
solution, and competition sets in for the production of a new close-canopy
of elongated leaf-members, giving the characteristic * Rush-habit ' (Spar-
gamum? Acorus, Iris, Butomus). In such case the * spearing ' habit of the
young leaves to reach the surface is enormously exaggerated ; and in the
production of an erect linear leaf-member the distinction between petiole
and lamina may practically disappear.3

1 The case of the Aquatic requires more extended notice, not only because aquatic vegetation is
particularly well displayed in the local flora of swamp-woodland and river-system ; but while the
shrub and the herbaceous types of the woodland show with sufficient clearness their reduction from
the arboreal habit, the general effect of much of the aquatic vegetation (especially Monocotyledonous
forms) is only remotely suggestive of a tree-organization. Resemblances are traced in details of
anatomy rather than in general morphology. A sequence of types is therefore arranged to illustrate
the more complete adaptation to an aquatic environment secondarily, in correlation with progressive
loss of original arboreal mechanism. To read the story the other way, as a rise of Angiosperms to
the land from comparable modern aquatics, involves some account of the manner in which such
structural features as main axes (cambium, timber) could have been evolved from originally wholly
submerged aquatics.

2 Sparganium ramosum is the typical ' Rush ' of Rush baskets, Rush mats, and Rush-seated
chairs, as a valued economic plant of older times. Fragrant Rushes for strewing on floors were
Acorus Calamus (leaves), and the Rushes of Rushlights Juncus effusus, flowering axes.

3 Schimper (1903), Plant Geography, p. 810, Ssoetes-type. Arber (1918), The Phyllode Theory
of the Monocotyledonous Leaf, Annals of Botany, xxxii, p. 465.

Subordinate and Herbaceous Flora 41

III. Where in turn such mechanism of orientation and erection in the
petioles wholly fails, the leaves droop, to float passively on the surface of
the water. With such relief from all necessity of mechanical support and
also from the possibility of desiccation, new possibilities open up for what
may be termed the anchored floating leaf. In fact so many problems are
solved by the adoption of passively floating leaves, that their anatomical
organization is modified to meet the new conditions; e.g., restriction of
stomata to the upper surface is readily effected when they were originally
on both sides. Such floating leaves become characteristic of a wide range of
aquatics, from facultative grasses to more particularly highly specialized
types of Dicotyledons. To such leaves increase of surface is essential, as
they lie in the horizontal plane only, and the plant becomes a-dimensional
so far as its photosynthetic area is concerned ; while the available space
becomes more restricted as rhizomes are condensed and the plants are gre-
garious. The leaves spread out to enlarged sub-orbicular form, with leaf-
mosaic on the water-surface, soon occupying all the room available ; but
capable of indefinite extension in open water so long as it is of no great
depth. The mechanism of petiolar extension gives the regulation of
the lamina to the depth of the water and its position in the leaf-mosaic, and
this becomes a limiting factor : e.g., Nymphaea alba may grow in ao ft. of
water. Such a depth of water is beyond the capacity of any tree-type, and
beyond the preceding aquatic habit ; so that the floating leaf opens up
a new field of operation to plant-forms, in which they are beyond the com-
petition of the older types of the land. In thus finding a ' new station ' in
the water, plants are not necessarily c driven off the land ' ; the latter
expression remains metaphorical as a poetic exaggeration of the facts,
merely because we remain on the land ourselves.1 It is difficult now to
visualize what such a fine plant as the Victoria regia of the Amazon may
have been before it left the land.

IV. It may be noted that such petiolar mechanism has again its

(limitations ; it cannot be extended indefinitely, and it does not meet the case
of casual alterations in the water-level, or seasonal periodicity of the supply.
That is to say, its failure may be expected ; e.g., at the beginning of the
growing period, or at the end of the season, many leaf-laminae may fail to
reach the surface at all. In such case a new type of submerged leaf may
come into action ; and where this proves efficient for photosynthesis a new
set of structural alterations may be called into operation. When so appar-
ently withdrawn beneath the surface, the photosynthetic area is no longer
2-dimensional in the horizontal plane, nor does it require to be vertically
elongated as in the rush-type. The necessity for the orbicular leaf vanishes,
though a linear form may still be useful where it lies in the flow of the
current. The plant-body again becomes 3-dimensional, taking all the light
it can receive ; the more so as effective light diminishes rapidly in intensity
beneath the surface of the water. Stomata are no longer required ; normal
transpiration is no longer effective ; the plant-form tends to regain an algal-
habit. Leaf-laminae reduce to thin crumpled expansions, or are dissected
to fine filamentous segments which space themselves in the medium, with
no special mechanical difficulties, admitting any light they do not use to the
members beneath them, and retaining in their reduction the pattern of the

1 Arber (1920), Water Plants, p. 324. Emigrants leaving this country for the colonies may be
said to be similarly ' driven out ' by financial, social, political, or theological pressure ; but they
leave of their own free will ; they are by no means the leavings of the population ; but on the
contrary, are distinguished by their greater enterprise in the search for new stations. The criterion
of success is adaptability to new conditions ; the non-adaptable are the real failures ; and by
adaptability is now understood a capacity for freely mutating under the stimulus of a new environ-
ment. The rest is lelt to natural selection.

42 Plant-life of the Oxford District

bundle-distribution of the older leaves of the land in skeleton-form. In
such manner the wholly submerged shoot becomes free of water to any
depth, so long as light-penetration is sufficiently good (i. e., in clean water) ;
and streams and lakes fill up with subaqueous vegetation, imitating in its
dense ramification the vegetation of the subaerial world, and recalling in
such retained form-factors the older vegetation of the sea, in which such
structural features were originally established in response to the necessities
of a moving medium. Though now so essentially distinct in acquired
anatomy of the land-plant, the general appearance of such submerged
aquatics is curiously algal, in dimensions as well as in texture (cf. Potamoge-
ton lucens in a strong current, P. pectinatus, P. crispus, Myriophyllum and
Rammculus fluitans as 6 ft. trails).

V. All aquatics so far mentioned remain attached to the bottom, and
are so far anchored, even when wholly submerged in the manner of benthic
algae, and they may grow in deep water, if this is only sufficiently clear.1
Yet here, again, the mechanism of attachment by adventitious roots is the
essential factor : where this fails, the plants are set free to rise to the sur-
face in virtue of photosynthetic oxygen, to become free-floating vegetation,
solving the problem of optimum surface, but left free to drift at the mercy
of current and wind, and with a feebler absorption system than ever before.
Such a new type of vegetation can attain no great dominance, any more
than do free-floating algal forms of the sea.2 Flotation depends entirely on
oxygen storage ; sinking in deep water may be fatal ; only by remaining at
the surface, and eliminating chances of drift (by gregarious mass-effects) can
any benefit be gained. Thus the minor types of plant which have adopted
this life, tend to imitate the broad expansions of the leaf of * floating
aquatics' (Lemna, Hydrocharis), while others are little advanced beyond
submerged forms (Elodea^ Lemna trisulca). The dilution of the food-solution,
the diminution of transpiration in forms floating in rather than on the
water, and the feeble capacity for absorption, tend to ultimate stages of
reduction, which render some of these forms (cf. Wolffia) the most diminu-
tive of Flowering Plants.3

VI. It is important to note that, so far, the general construction of the
vegetative and photosynthetic shoot-system has been alone considered ;
but similar conditions of failure may characterize the portion of the shoot -
system set apart for reproductive functions, as special inflorescence-region
of the plant, inflorescence-axis, and even flower, wholly independently.
The two regions of the plant-body are not exactly on the same footing, and
have to meet quite distinct problems : since the vegetative portion has to
bear the onus of obtaining the food-supplies, while the reproductive shoot
with its cycle of reproductive phases may be restricted to the more favour-
able period of the year. As a rule, the reproductive portion will be found
to be more * conservative ', to retain much more evidence of the older phase
of land organization, and to lag behind the advancing specialization of the
photosynthetic leaves. The flowering scheme of an aquatic has little refer-
ence to what its leafy shoots may be doing, and throughout the range of

1 Cf. Schimper (1903), Plant Geography, p. 792, for Posidonia in the Mediterranean at
30-50 fathoms.

8 Pistia and Eichornia as free-floating forms of tropical rivers become pests, as the gregarious
habit gives them a stationary character. Cf. Arber (1920), p. 213.

3 These classes are by no means exhaustive, and types grade into one another even in the ontogeny
of a single individual ; that is to say a certain range of plasticity in the organism may obtain.
Batrachian Ranunculi may produce both ' broadened ' floating leaves and ' dissected ' submerged
laminae on the same shoot. Sagittaria with normally erected subaerial ' arrow ' leaves in rush-
habit, in deeper water gives arrow-forms broadening and floating on the surface, and in still deeper
water the attenuated ribbon-petiole (6 ft.). Free floating forms are commonly mud-plants with little
holdfast.

Subordinate and Herbaceous Flora 43

aquatic type, the original multibranched inflorescence-axis, erected from the
water, affords a conspicuous example of this capacity for the retention of
older machinery of the land (Sparganium^ Hottonia^ Utricularia). Reduc-
tion of such a compound subaerial inflorescence-system follows rules similar
to those of land-forms ; problems of size of floral mechanism, anemophily,
and seed-output, may reduce or modify the constructions to simple spikes, or
ultimately to single flowers. These, again, may be affected by the relation
of the mechanism of adjustment of the floral axes or inflorescence axes to
the depth of the water, in the manner of petioles ; and further effects are
observed as such axes may retain photosynthetic mechanism in the manner
of petioles. Thus in plants with the rush-habit in leaf-members, a com-
parable rush-habit may be attained in the inflorescence axis (Butomus), and
such axes (culms) may be left as subaerial shoots when the leaves are sub-
merged (Scirpus lacustris). Types with floating leaves may similarly attain
adjusted surface-floating flowers (Nymphaea) ; but in an older phase these
were not so accurately managed and stood clear of the water (Nuphar,
Limnanthemum). In the limit, forms with submerged leaves may also fall
back on submerged flowers (Potamogeton densus, Zosterd), and pollination
in the water may replace anemophily ; but even in submerged aquatics the
projection of the flower-spike above the surface is more usually arranged for
(Potamogeton lucens, Hottonia, Batrachian Ranunculi). The two systems of
foliage shoot and reproductive shoot require to be kept quite distinct, as are
their essential functions and problems.1

Such different types of plant-form, ranging from the timber-tree of
high forest to the lowliest free-floating aquatic, collectively constitute the
Angiosperm flora of the present world. Every tropical forest contains its
dominant evergreen forest-trees, with subsidiary associated epiphytes,
parasites, saprophytes, and climbers (lianas) ; each of these exhausting in
turn the possibilities of the new station and new mode of life they have
found, and growing in active competition with the main crop of trees, as the
full ecological equipment of such a forest-formation. All deciduous forest,
similarly, may retain examples of these primary and secondary constituents
of the optimum forest, with added tertiary formation of minor trees and
shrubs, as also a greater wealth of herbaceous ground-flora constituting the
underwood and woodland base. Open land beyond the forest zone is given
over to xerophytes, rock-plants, and prairie-forms ; swampy woodland and
water-courses supply all ranges of aquatics, rush-types, floating, and sub-
merged forms. Angiosperms, as the modern dominant race of plant-forms,
culminating far beyond the older Pteridophyta of the first land-surface, have
by this time invaded all the available biological stations of the world.2
These stations present a mixed Angiosperm flora which is the effective
solution of the special biological problems of the environment, taking into
consideration the past history of the race, and the way it has come, as
originally seed-producing trees of high tropical forest. That is to say, the
story of plant-life can be only read one way. Given a tree-phylum and the
world to itself, there can be little doubt that in the course of time, its
descendants would be found modified to suit the biological conditions of
every special station, very much in the manner that plants do now. In
ancient times, preceding races of vegetation have pursued much the same
course, indicating that the general conditions have not greatly changed.
A few relics of the world of Pteridophyta in Pre-Palaeozoic times

1 Cf. Arber (1920), loc. cit., p. 6.

2 Just as in the parallel animal kingdom, Reptiles once dominated the land-surface, Mammals
do now, with aerial Bats, regressive marine Cetacea, fruit-eating monkeys, tree-eating elephants,
grass-eating deer and cattle, as well as carnivorous, insectivorous, herbivorous lines, all making up
the animal equipment of a continental area of woodland and prairie, river and sea.

44 Plant-life of tJie Oxford District

are left, as Reed-types (Equisftum), free-floating (Azolla), saprophytic
(PsilotUHt), xerophytic, epiphytic, and climbing (Lycopodium, Selaginella^
Lygodiuni)) while their prototypes of high forest have vanished, or only
remain in the form of coal. Similarly at the present day, convergence in
biological habit, or association in the same ecological station, is no indica-
tion of ' affinity ' or relationship. Existing families of Angiosperms may be
as remotely related as are the few residual types of Pteridophyta. Some
families are now left predominantly aquatic, others may be predominantly
or solely forest-trees ; others are now almost wholly herbaceous. The flora
of every country containing the essential biological stations is a complex of
the surviving protagonists, similarly specialized for their special problems,
along many lines of remote affinity. In all parts of the world the associa-
tion of similarly modified plant-forms in corresponding biological formations
gives a certain fades to the partial flora, which is distinctive ; though the
actual forms concerned may be phyletically wholly distinct, and making the
best in their own way of what equipment they may have inherited.

The British Flora, as the deteriorated representative of deciduous
forest-land remote from the tropics, affords a wide range of biological
stations, woodland, open ground, and aquatic environment. It thus presents
a complex in which there is room for something of everything : all bio-
logical lines are represented, even if only by one or two forms in an
attenuated scheme. It still retains a few evergreen trees, now sub-dominant
to the main series of deciduous forest-forms. Underwood trees and shrubs
are well represented, with not only an abundant ground-flora, but a few
residual representatives of the secondary vegetation of the tropical forest as
parasites, epiphytes, saprophytes and liana-climbers. Open exposed ground
beyond the woodland area, gives an abundant variety of xerophytes in hot
summer : short-season plants mingle with the grasses of prairie-land ; all
grades of aquatic are met with in swamp-woodland, ditch, and open river.
The flora as a whole includes a series of samples, as the country itself affords
a wide series of samples of climate, geological formation, and botanical
stations.1

So far, again, no special reference has been made to the remaining
vegetation of older epochs in the evolution of the modern plant-kingdom,
as illustrated in the few residual Gymnosperms, the feeble representatives of
Pteridophyta, the wider range of Bryophyta (Mosses), and the numerous
and varied representatives of the still older range of Algae of freshwater
(including Plankton-forms), and their saprophytic homologues of the land
(as Fungi and Lichens). These are left for future consideration. The more
conspicuous and dominant forms of the modern flora have the first claim ;
this being the more emphasized by the fact that there is no evidence that
the full progression has taken place in this country, or through the inter-
mediary of any such archaic types. All are equally immigrant, and owe
their special characteristics to conditions of environment in probably far
distant lands.

Owing to the local predominance of swamp conditions in the older
Oxford Valley, the progression of water-plants becomes of special interest,
as superimposed on the organization of the herbaceous forms of woodland
and woodland-swamp, introducing factors which are new rather than
regressive. But the general trend of events is so far outlined. Though
there may be indefinite breaks in the story of any given plant, as well
as divergence in special variations of the different problems, and it is
understood that the progression took place largely elsewhere before exten-

1 Tansley (1911), Types of British Vegetation, p. 15.

Subordinate and Herbaceous Flora 45

sion to this part of the world, the general sequence of events is so far
outlined, and it should be sufficiently clear that : —

(1) Every aquatic of the open stream once grew on the bank.1

(2) Every bank-aquatic was once a plant of damp woodland under-
growth.2

(3) Every plant of swamp-woodland was once in normal woodland as
a herbaceous perennial.

(4) Every herbaceous perennial was once an underwood shrub.

(5) Every underwood shrub was once a tree of high-forest.

Each stage in such progression calls for further detailed analysis ;
but the present object is to show that the story is unified, and hangs
together. A local flora is not a collection of disjointed units, or phases of
special creation, but one progressive whole, in which each part has its
proper value and status. This is what is implied by the evolutionary
and ecological standpoint.

The advanced submerged obligate aquatic is perhaps the type furthest
removed from the primary forest-tree ; and just as the tree-type required
to invent and specialize its arboreal factors from the horizon of a trans-
migrant seaweed, so these factors are gradually lost in the herbaceous
perennial on regression to water as a rhizomatous form, or are retained as
vestigia, to be last discerned in the floral shoots and details of the floral
mechanism of reproduction. It is necessary to have some working hypo-
thesis in tracing such a progression, and the foregoing assumptions are
based on the causal factors of light and water-supply as bearing on the
nutrition of the individual, — the loss of primary arboreal factors being
compensated by precocity of flowering and fruiting, with increasing
specialization in the mechanisms of cross-pollination and seed-dispersal,
as also of increased vitality in perennation. Conversely, while it appears
possible to trace the progression of the obligate aquatic, by the loss of all
arboreal factors, there is little evidence that such a series will ever work
backwards all the way, or that the full type of a forest-tree has been ever
derived from such aquatic' vegetation. The story of the Flowering Plant
(or Angiosperm) is restricted to primary forest-forms, the origin of which
from necessarily smaller types of transmigrant vegetation appears at present
hopelessly beyond recall ; though the existence of primary land-plants in
the herbaceous form may be indicated at the older horizons of Bryophyta
and possibly Pteridophyta.

It seems a far cry from the Duckweed of a standing pond to a timber-
tree of high tropical forest ; since the time required for such a transition is
beyond our perception, once it is granted that there is no reason to believe
that the rate of progressive evolution has been ever greater than it is at the
present day. A period of a thousand years makes no appreciable difference
either in climatic conditions, or on the indigenous flora. The December
frost of 1142 was recorded as a phenomenon, and was no more intense than
that of March 1895. The vegetation was essentially the same in woodland
and any valley-pastures in Roman and Neolithic times ; and it has been
wholly renewed since the last maximum of Glacial cold. The time since
the post-glacial river-terraces were begun must be reckoned in hundreds of
thousands of years ; when it is noted that the greater depth of the river-
valley was cut down apparently in milder epochs, with no marked snowfall,
much as at the present day, with slow erosion and deposition of alluvium.

1 Since all (with the exception of Wolffia) retain roots as essentially soil-organs.

2 Rhizomes of many plants follow the water down the bank, to 3-6 ft. trails, extending into the
water, or floating. Cf. Epilobium hirsutum, Potentilla rcptans, Lycopus europaeus, Polygonum
amphibium, Agrostis stolonifera, in widely related families.

46 Plant-life of the Oxford District

This implies that the Pre-glacial period may have been quite 10 times as
distant, or may be estimated in terms of a million. Yet, according to
C. Reid, no less than 75 species^- of the present flora were even then sufficiently
established to be fully recognizable ; leaving the period required for their
full establishment indefinitely remote. All these plants, again, had come
to this country as migrants, specifically fixed and long-established ; the
place as well as the time of their origin is left open. Allowing a margin of
error for such determinations, it begins to be evident that species, as they
are now reckoned, must go back at least to the Tertiary. If genera became
broken into modern specific forms in the Tertiary, for which a time-distance
of something like 50-100 millions has been claimed, Families of still older
order may date back to the Cretaceous ; as in turn the primary lines of
divergence between Gymnosperms and Angiosperms may be of Palaeozoic
antiquity (some 300-400 millions). The fact that forest timber-trees
(Cordaitineae) were in existence in the Upper-Devonian, indicates the
immensity of the gap still required to account for the rise of a timber-tree,
producing flowers and seeds, from the algal prototypes of the transmigra-
tion,2 and the possibly hundreds of millions of years required to build the
organization of the arboreal habit from its constituent factors.

V. THE HAND OF MAN

Of all influences which have been brought to bear on the character of
the flora up to the present time, that of human agency is overwhelmingly
preponderant, and the more disturbing as it is often erratic in action and
bearing consequences wholly unforeseen. Little objection can be taken to
such influences by the naturalist, however much he may pine for a virgin
forest at his door, since it is only by such human interference that the locality
has been made available for human life in the first instance, and to it we owe
the fact that we are here at all to examine what is left of the original
condition.

Without going back to the remote ages when the mammoth came down
to drink at the river-terraces,3 or the reindeer and woolly rhinoceros wandered
over the site of the city, it is clear that even at the beginning of the historical
epoch the land was covered with dense forest, in which roamed wolves, wild
boar, and red-deer; the forest-canopy being only broken on the exposed
more arid slopes of some of the adjacent hills, and again in broad stretches
of swampy ground formed by the damming up of the river in winter flood-
time with its narrow outlet below Sandford.4 In every type of floristic region
the effect of human effort and interference is to be traced; not only as
considerably modifying the nature of the ecological associations, but rendering
them largely of temporary duration, liable to disturbance the effect of which
is wholly incalculable at any time. Thus of the original Forest-land no trace
remains in anything which may be regarded as approaching its primary
condition. With clearings for arable and pasture-land extending over the
slopes of the river-basins above the alluvial line, patches of woodland remain
as Wytham Wood and Bagley Wood, each of an area extending to about
a square mile. Smaller portions survive as copses (Radley Wood, Stow Wood,

1 C. Reid (1899), Origin of British Flora, p. 171.

2 Thalassiophyta and the Subaerial Transmigration, Bot. Mem. iii, 1920.

3 Bones of Ekphas primigenius were dug up in the gravel of Magdalen College Grove in 1921.

4 Traces of woodland extend practically to the top of Shotover ; a few trees (Pine and Elm)
grow on the exposed top of Cumnor Hurst. Forest-land deteriorated to Willow and Alder-scrub
may come down to the alluvium near the present river (Godstow Holt). Only Wytham Great
Wood, and more definitely Nuneham Woods, still come down to the river-margin.

The Hand of Man 47

Wick Copse), more usually in the form of derelict land in which swampy
conditions still prevail (Sandford Brake), or merely left as a convenient
source of rough wood for minor agricultural purposes, faggots and firing.
As the trees are cut down, and regeneration follows naturally from the old
stools or by seeds, or more effectively by planting, the original arboreal flora
is wholly replaced, and only the underwood remains in anything like its
original condition ; though in variety of species, again, this suffers rapid
diminution, as smaller sections are more and more isolated, and the leafy
canopy deteriorated. Extreme felling for timber and firewood leaves only
thickets of thorn or coarse scrub on dry situations, or willow and elder-scrub
in wet tracts. Other woods are allowed to run derelict with the undergrowth
encouraged as subserving the protection of game.

The channels of the larger streams with their submerged and floating
aquatic forms, and the vegetation of their banks merging gradually into the
meadow and woodland associations adjacent to them, become subject to
arbitrary change. The stream is artificially banked (with concrete), and the
bed is dredged for ballast-gravel, or to deepen the navigable channel, to
control the flood-water in winter, and pass it off as quickly as possible from
low-lying levels, as well as scoured of weeds in summer. The main river is
locked (with equipment of weirs, lock-gates, and lashers) in order to subserve
transport, and with the effect of holding the water up over the dry summer
in irrigation channels, and differentiating the land above the lock from that
below. The bed of the navigable stream is subject to periodic cleaning of
the weeds. The original aquatic flora is to be sought in backwaters, ditches,
and smaller streams, often long uncontrolled, but again largely artificial, and
liable to interference by extended systems of drainage, as ' swamp '-land
becomes agriculturally ' improved ' and taken into cultivation. In repair of
lock- and weir-mechanism, whole sections of the main stream may be allowed
temporarily to run out.

The broad water-meadows of the alluvial area are distinctly artificial,
and the result of human activity, as these levels, cleared of casual trees and
scrub, are laid down in pasture to be cut for hay each summer, with the effect
of keeping down all attempts at colonization by woody and larger perennial
growths, and thus relegated to grasses and the associated plants of meadow-
land ; as again a very secondary selection of the plants normally characteristic
of such localities, together with many intrusives and importations. In the
water-meadows this effect is the more emphasized by the mowing of a second
crop in September. Nor can it be claimed that the original flora persists
unchanged in the ditches and hedges of the alluvial district. The ditches are
artificial as drainage-systems, populated by a few stray aquatics brought by
flood-water ; neither standing ponds nor streams can be depended on as
primary constituents, while the hedges with heaped and drained earth-banks
are stations equally artificial, which freely regress to scrub, and so far carry
vestiges and strays of more woodland habit ; in both cases, again, supporting
an enfeebled flora of a few common types, as they become the more isolated
and remote from similar stations and the conditions more restricted, mingled
with casual strays and the intrusive weeds of cultivation.

Of the land above the alluvium, cleared by early settlers, and now
permanent pasture or under arable cultivation, — the pastures, close-cropped
by cattle, become grass-land with intrusive weeds as thistles, thorns, briars,
and nettles ; and where, if kept down by mowing, these are more preponderant
along the hedge-banks, the latter are again artificial productions as well-
drained earth-banks of no great thickness, carrying a sparse population of
bushes with a few trees whose roots alone penetrate deep into the subsoil.
Such arboreal forms of residual underwood as hedgerow bushes afford shelter

48 Plant- life of the Oxford District

to birds which largely propagate them by berries (Hawthorn, Sloe, Elder,
Viburnum, Rosa, Rtibus, Privet, Honeysuckle, Bryonia, Solanum Dulcamara).

The arable-land, with improved methods of agriculture, becomes1 cleaner'
and cleaner, with few weeds beyond those of cultivation, imported with foreign
seed and characteristically annuals and ephemerals, increasingly artificially
selected as their life-period coincides with that of the crop concerned ; each
crop carrying its own special weeds. The business of an agriculturalist, in
cultivating one or more special forms or races of plant for economic purposes,
is, in fact, to clear out every other associated plant as a c weed ' which,
otherwise robs the crop of water and expensive manures.

The same standpoint receives emphasis in the case of the allotment
cultivation of vegetables, and the more select and aesthetic gardens growing
decorative plants and florists' flowers, in which intrusive ' weeds ' are kept
down more or less rigorously as vulgar interlopers ; while a few plant-forms,
often aesthetic monstrosities, are selected by human agency in a wholly
erratic manner at the expense of the rest of the vegetable and animal kingdom.
Allotment-holders are bound by regulation to keep down their weeds.

The Willows which form so characteristic a feature of the margins of
low-lying alluvial meadows, with their remarkable exhibition of epiphytic
vegetation, owe the latter character, as also their special configuration, to the
manner in which they are periodically pollarded ; and the complex secondary
vegetation recorded in one year may be wholly swept away as the trees are
stripped to barest stumps, the usual period being anything from 2-10 years.
Abnormal effects also follow extreme lopping, as the plants are destroyed by
Fungus-attack, ultimately reducing to hollow shells, variously split, with
descending pillar-roots and hollow axis of touch-wood. Similar irregular
growths under human maltreatment are seen in the stools of oak-coppice,
and the deformities produced by continual cutting back and pollarding of
trees in hedgerows, with often fantastic results (Ash, Black Poplar, Elm).
Normal epiphytic vegetation is extremely rare, beyond the Mosses and
Lichens of the underwood.1

Hence in every grade the study of the original flora of the district
reveals its subordinate status, and one has to endeavour to trace it to the
causes which may have produced it beneath an entanglement of secondary
effects of human interference, the actual agents of which not only display
a supercilious manner in dealing with the deteriorated vestiges of the plant-
life of the neighbourhood, but often express wonder at, if not pity for, those
who consider the remains of such original vegetation worthy of more than
a casual notice. To the forester, attempting to grow trees for commercial
gain, the inferior vegetation is interesting only so far as it becomes a
nuisance, or harbours fungus and insect-forms which may be migrant
' diseases ' of his trees. At best it is to be tolerated as protecting seedlings
from the wind, conserving soil-moisture, or as a 'soil-indicator'. The agri-
culturalist, again, cannot conceive why to many the wild flowers of his
hedges are more interesting than the crops of turnips and wheat in his fields ; 2
as the allotment-holder seldom thanks anybody for admiring the fine crops
of injurious or imported weeds coming up among his cabbages or on his
rubbish-heaps ; while the floriculturalist who can control a garden * without
a single weed ' is regarded as deserving of the highest compliment that can
be paid him.

The effect of an increasing population in the immediate vicinity of a large

1 Polypodium vulgare alone has been found epiphytic on Beech-roots and on old Pear-trees.

2 For much of this contemptuous regard, the field-botanist of the last century is largely
responsible. By hunting a farmer's fields for specimens of the British Flora, he put himself definitely
on the side of the farmer's enemy (the weeds), instead of taking any interest in the production of new
strains of the agricultural crops.

I

3

<u

TD

8

£

<U

7- Bagley Wood, Aug. 1922. Alder Coppice over Bracken.

The Hand of Man 49

town naturally introduces much abuse of the local flora. Children, using the
adjacent fields and by-ways as their natural playground in increasing numbers,
carry out an active campaign of destruction on all plant-life within reach.
Hedges are broken and trampled, more flowers are destroyed than picked ;
trees broken, rotten willows burnt out, aquatic vegetation damaged by sticks
and stones, become the general characteristic of the fringe of the inhabited
areas, together with a general devastation of attractive flowers wherever
available. Such mischief on the part of children is normal, and no one
grudges them the pleasure of picking nosegays of Buttercups and Daisies,
Caltha^Fritillaria^ Lychnis Flos-cuctdi, Cardamine pratensis, Bluebells, Prim-
roses, and Cowslips, or foraging for nuts and Blackberries, as these appear
in quantity, since there is enough for all : but adults who should know better,
with wider range, will equally devastate hedges and woodland, grabbing all
available specimens of rarer flowers of aesthetic value for alleged decorative
purposes, or expressing their delight at the return of spring-vegetation by
stripping all in sight, as if the supply were inexhaustible. Collectors also
show no compunction in taking any rare plant for their ' herbarium ' or
1 exchange ' ; hence rarities are ruled out of an ecological flora, however
interesting they may be as vestigial survivals. Indigent wastrels, again,
strip the countryside of flowers, fruits, and roots, as these may present some
slight commercial value (Fritillaria, Typha^ Fern-roots, Guelder-rose berries,
Spindle-tree, and even Phragmites).

Everywhere within walking-distance of the town-area, general deteriora-
tion of the flora follows the effect of increasing population on cultivated
and enclosed land. Hedges are broken by picnic-parties in search of fuel,
and within recent times the holiday extension of Thursday afternoons has
had an effect which parallels that of the Saturday holiday of the children.
The extension of ' Summer-time ' has had a further noticeable effect on the
invasion of the countryside, and within the local district has emphasized the
destructive effect of the school summer-holidays. In such case it is not
surprising that the amount of agricultural and forest-land closed to the
public steadily increases. Hedges are liberally mended with barbed wire,
and notices bearing reference to the alleged fate of Trespassers meet one at
every turn. The wandering botanist is naturally mistaken for a tramp off the
beaten track,1 or for an officious inspector of something or other. Hence
modern works on the flora can be eked out with floristic records of past ages,
now unavailable and useless : to give the locality for a rare or interesting plant
is to sign its death-warrant. As such changes are increasingly rapid in this
generation, a record may be useful for future reference.

It may be admitted that the ever-increasing town-areas spread out as a
canker eating into the life of the countryside, that it is the natural instinct of
much of the human race to defile everything they come into contact with, to
destroy or enslave every other form of life, with only the blindest ideas of
improving their own. This is but the age-long story of natural selection and
the relation of the animal to the plant, — the more obvious in a small district,
owing to the ruin and damage readily effected by a few unscrupulous or
ignorant agents, whose action, though deplored by their betters, remains un-
checked. Local areas are bought up to prevent exploitation at the hands
of the speculative builder, but the general public is ruled out or admitted
uncontrolled. Nature-sensitives admiring the beauties of the local flora are
not happy unless they can take away as much as they can carry with them ;
leaving behind in exchange ginger-beer bottles and orange-peel. Picnic-parties
also trample the undergrowth, damaging fences and lighting fires. These
restrictions are not confined to the district ; they represent the general tendency
of the age within all growing urban areas, and appear unavoidable.

1 ' In hat of antique shape, and cloak of grey ', Matthew Arnold.
D

50 Plant-life of the Oxford District

On this account it cannot be \vondered at that the few remaining examples
of woodland and waste, as well as cultivated fields, are becoming more and
more closed against the public, and the favourite collecting-grounds of an older
generation of botanists are destroyed or are no longer available.1 This applies
more particularly to Wytham Wood, Hen Wood, Radley Wood, Bullingdon Bog,
Magdalen Wood under Shotover.

Bagley Wood, closed to the public, is utilized for instructional purposes
by the Schools of Forestry and Botany. It is interesting to watch the fate of
the 30-acre University Enclosure on Shotover (1908), devoted to the use of
the Public.2

In a short time the public will be restricted for floristic studies to the few
foot-paths over fields still left open as old rights- of- way, the dusty or tarred
roadside, the tow-path and the open river, with alluvial areas as Port Meadow,
and Iffley Fields when these are not up for hay, or to their limited experiences
as allotment-holders.

But there is another side to the story. The general aspect of a well-
wooded countryside, even at its best, is but the effect of human activity and
cultivation ; however much the appearance of forest- and pasture-land may
appear natural because it has been the same within living memory, or even
historical record — it is by no means * primitive '. Its very maintenance at the
present condition requires careful prevision and active judgement on the part
of the human population. Woodland, grown and cut under any sort of
rotation, however vague, is not original forest. Pastures are maintained at
their functional standard by definite and intentional care, grazing, mowing,
and hedging. The very accessibility of the district, to say nothing of the
admirable motor-bus service in recent times, is the effect of the maintenance
of very modern roads and foot-paths, without which little could be done.
One does not do much scientific work in a trackless jungle. Woodland
paths, if not kept cut, become practically impassable in a few years. Derelict
land runs to dense thickets, soon wholly impenetrable owing to thorns and
briars, however admirably adapted to the modern necessities of boy-scouts.
The countryside as we know it is the wholly artificial product of a certain
standard of human culture, and it is only maintained at a similar biological
horizon by continued work. Once the hand of the farmer, forester, or
gardener is relaxed, the effect is soon apparent. Primitive scrub, jungle,

1 Stow Wood, though much reduced in area (30 acres) is apparently still open by the courtesy of
its owner, though the stereotyped minatory notice is attached to a conspicuous tree ; and the same
applies to Headington Wick (1922), as still a unique area. Horspath Common (Bluebell Valley) is
still available, but 'Open ' Magdalen is enclosed and wired, and 'Open' Brasenose, fenced 1922, is
apparently to be cleared. Pickett's Heath, with the * Signal-elm ' of Matthew Arnold's verse (1861),
has been completely devastated, though the tree remains.

2 A notice, remarkable for its auto-suggestion, reads : ' This Piece of Ground is the Property of
the University of Oxford. It is open to Visitors, but they are requested to refrain from pursuing the
game, and catching Rabbits, from disturbing Birds' nests, Lighting fires, Plucking Flowers, Pulling
up roots, Injuring the trees, the brushwood and the Fences. Offenders will be Prosecuted. By Order.'
At the present time (1922), one looks in vain for game, there is no fence at all, the notice is
damaged, the gate is gone, only the stout gate-posts defy removal ; marks of fires are numerous, and
a considerable portion was burnt 1921.

Cf. Radley Old Wood (1922), ' Persons picking flowers or roots, or otherwise trespassing, will
be Rigorously Prosecuted. No tickets issued?

The conventional declaration that ' Trespassers will be prosecuted ' is found at Magdalen Wood,
Brasenose Wood, Coombe Wood, Sandford Brake Wood, Plowman's Copse, Tommy's Heath.
Railway Companies protect themselves by prescribing a 40*. fine for trespassing on the line, or
leaving level-crossing gates unlatched. The River under the guidance of the Thames Conservancy
remains open ; ' All persons using the River Thames, and the Locks, Works, and Towing Path
thereof, must take them as they find them ', and use them at their own risk.' Unusual solicitude for
the wayfarer is shown by a recent note (1922) — 'Persons undressing or dressing on or about the
river, without shelter, render themselves liable to be prosecuted.' In comprehensive botanical
interdict, however, the By-laws of the Thames Conservancy (1898), are by no means behind, and one
is warned, among other things, 'not on the river or banks or towing-path thereof, to do or cause or
incite any other person to destroy or injure any flowering or other plant, or any shrub vegetation
tree-wood or underwood', under a maximum penalty of

The Hand of Man 51

and swamp are not inviting, nor would they repay much scientific examina-
tion. Ecological experiments pre-suppose some sort of control of the
biological factors. Modern attempts at saving tracts of country as bird-
preserves or sanctuaries for indigenous fauna and flora, however well-meaning,
have no future value ; any more than modern forestry with its serried rows
of saplings will restore the Neolithic forest. Nothing in nature stands still.
Just as one cannot restore the original condition of swamp-woodland in the
Oxford Valley, with its necessitated human life in wattled huts on scanty
diet, and would not do any scientific work if one did ; so it is now equally
impossible to maintain a wild jungle at one's door or in the back garden.
The seeming wild is not so very wild after all ; the old English term ' waste '
is peculiarly applicable. Any sort of selection, whether natural or artificial,
implies the ultimate advantage of a few types at the expense of the others.
The relations that have made the countryside what it is during the last
1,500 years represent the influence of a set of physical factors, as distinct
from the original selection of nature in post-glacial times, as it is from the
future still increasingly artificial selection of the farmer and forester. When
townspeople bemoan the ruin of the country as they have seen it, or read
about it in the past, it is only a change of ecological conditions that they are
witnessing ; whether better than any previous changes in the past, or not,
may be left for the future to decide. The present time is one pre-eminently
of transition and survival ; it is the cause and the manner of the change
which is the present centre of interest ; though it may be admitted that the
odds are usually on the side of pessimism.

As all floristic regions are thus entirely secondary and artificial in such
fundamental features as water-supply, destruction by grazing, felling, draining,
clearing, and direct human interference, it will be observed that : —

(1) The exact valuation of the indigenous flora becomes a matter of
difficulty.

(2) The nature of the alien-flora, immigrant at various times, has to be
reckoned with.

(3) No effects of succession can be traced beyond such cases as: — the
irainage of a ditch, the replacement of meadow-land and pasture by allot-
icnts with their weeds of cultivation, or the effect of close-planting of forest-
plots on the flora of forest-clearings.

(4) No continuity of observation over a long-continued period can be
guaranteed ; at any time the association may be destroyed, removed, or

leared, by agencies beyond the control of the observer.

At any rate, one thing is clear, — with the removal of man and all his
works, the flora would not take long in reverting to its original condition ;
ind with man would go all his associated weeds and aliens, as well as his
lependent food-plants, trees, and animal races. Possibly the whole efforts
of human activity and so-called progress mark but an incident in the life of
the indigenous flora. The latter was, in primary essentials, the same as it is
low, 10,000 years ago: the boldest speculation can scarcely look forward
to the probable status of the human population in 10,000 years time. But
it is quite clear that if man is not here, the same old flora will be. Thus,
lamp woodland, if not forested, would become more or less impenetrable
jungle (as in parts of Headington Wick). Neglected hill-pastures soon revert
to thorn-scrub of the type seen in Headington Quarry-heaps. All arable
lelds, left to themselves, would follow suit, and become much as their hedge-
>anks. The green pastures of the water-meadows would be converted into
Billow and thorn-scrub. The ditches, blocked by vegetation and fallen
:rees, would cease to drain the flats, and these would revert to swamp-
woodland. The river, no longer controlled by the lock-system, would resume

D 2

52 Plant-life of the Oxford District

its ancient winter-flood habit, and tend to run out entirely in the summer
months. In 100 or 200 years it is probable that the ruins of all the local
buildings would be represented by grass-covered mounds and rubble-heaps,1
as are the sites of the earliest quarries at Headington. The suggestion of
re-afforesting Bagley Wood with Larch and other alien conifers in close order
implies the practical obliteration of the woodland as it has existed for at least
many centuries. Yet the isolation of a tract of land at Cothill for purposes of
Natural History, and the special study of the local fauna and flora, equally
implies the production within a few years of an impenetrable undrained
jungle of reeds and scrub, unless it can be intelligently 'preserved* from the
standpoint of the organisms it is desired to perpetuate. The first law of all
autotrophic life is growth, in response to certain conditions of the environ-
ment. If these last are changed, the response is altered or the plants dwindle
and die out. The indigenous flora in the immediate vicinity of the town is
in a state of rapid deterioration in response to the increasing difficulties of its
struggle for existence ; the utmost that can be done is to attempt to retain
it as little altered as possible. How to ' improve ' it in a botanical sense is
beyond speculation, though foresters, agriculturalists, and gardeners may
have their own special views on the subject.

From such general consideration of the condition of the earlier indigenous
flora and the effect of human activities, as also of the introduction of new
types of plant, largely replacing the old in some stations, sub-dominant in
others, or still wholly secondary and assisted, — it follows that many of the
most characteristic features of the landscape and ecological formations may
be the effect of compromise and mingling of these different factors. It is
therefore convenient to consider them separately, as they give rise to com-
munities of special biological interest, of which the component factors may
not be obvious at first sight.

As such special cases may be distinguished :—

(1) Woodland and Copse.

(2) Underwood, Forest-plots, and Clearings.

(3) Hedgerows and Hedgebanks.

(4) Regressive and Derelict Woodland.

(5) Grassland and Pasture.

(6) Roadside and Waste.

(7) Crops and Weeds of Arable Land.

(8) Allotment-areas.

(9) River and Ditch Flora.

(10) The Regression of Derelict and Cultivated Ground.

1 The finest mediaeval building in the district was Osney Abbey, with its accessory buildings
rivalling any Oxford College of to-day. Built in 1129, it was dismantled at the Reformation.
Much of the stone-work, as also the big bell (' Tom ', commemorating Thomas a Becket), were
transferred to Christ Church. No trace now remains of this great building. The site was ploughed
over in 1718.

53

VI. ARTIFICIAL PLANT-FORMATIONS
Woodland and Copse.

From a well-wooded district of original forest-formation1 the land
has become progressively agricultural by reckless cutting down of the trees
to promote pasture rather than tillage, very much in the manner continued
by British colonists in the Eastern States of North America in the seven-
teenth century, and in New Zealand in the nineteenth. Huge trees were
commonly felled and buried in trenches where too big for conversion or
transport ; 2 but the necessity for fuel-supply always remained ; the latter
problem becoming the more intensified with the increase of urban popula-
tion. Portions of residual woodland were left near farmsteads, and more
so in the case of large estates, to be retained as coppice (copse) growth.
Far-seeing colleges acquired their own tracts of woodland (Brasenose Wood,
Magdalen Wood, Bagley Wood). Minor copses scattered very uniformly
over the country afford the best examples of the state of the original
woodland, with surviving types of undergrowth where the canopy was not
allowed to become too dense. In the county as a whole,3 86 per cent, of
the area is now brought under cultivation for crops or pasture, leaving
about one-seventh as residual woodland. In the Oxford district of 30
square miles, little more than 3 square miles can be said to be forested to
any extent.4 A rough distinction may be drawn between copse, as affording
fuel and billet-wood, and woodland, growing high-forest for full-grown
timber. No extensive tract of anything that can be called ' primary high-
forest ' remains ; the nearest approach to it being seen in planted woodland
allowed to become more or less derelict as preserves for game (cf. parts of
Wytham). Such districts, having been undisturbed for long periods of time,
give a very full mixed undergrowth and ground-flora. The Royal Forest of
Wychwood, 10 miles NW., was the last considerable tract of woodland in
the vicinity (3,735 acres); this being deforested, 1853, with somewhat
unsatisfactory results. The nearest extensive old woods are of poorest
quality on the Oxford Clay at Stanton St. John, 5 miles NE. : Stow Wood,
a fragment of a much wider area on Corallian, is now little more than a
copse (30 acres). Bagley Wood, Wytham Great Wood, and Hen Wood,
are left as isolated tracts of once continuous woodland, capping the hills ;
much of these districts being on land with little surface-water supply and
no springs, hence useless for farmsteads. Nor can such ground be taken as
really typical of what the best woodland would have been. The same
applies to wooded steep slopes of ravines and gullies (Wick Copse,
Hinksey Ravines).

All wooded tracts, continued under some sort of forestry practice, may
be included as (i) Tall Coppice, (2) Underwood.5

1 In the sixteenth century Camden (1586) records forests as the feature of Oxford scenery.
Shotover was a forest in which Milton's grandfather was a ranger. Waste and moor stretched across
Bullingdon to Magdalen Bridge. Much of the forest was cut down during the Civil Wars of the
seventeenth century. In the eighteenth a mania for enclosure set in, and in the nineteenth everything
left was enclosed on some pretext or another. The twentieth century sees, with minor exceptions,
the general public denied access to the residual traces.

2 Plot (1705), Natural History of Oxfordshire, p. 165.

3 Orr (1916), Agriculture in Oxfordshire, p. 193, Statistics.

4 Plot (1705)* P- 52- 'The hills, 'tis true, before the late unhappy wars, were well enough
beset with woods, where now 'tis so scarce, that 'tis a common thing to sell it by weight, and not
only at Oxford, but at many other places in the northern parts of the shire ; where it is brought to
Market, it is ordinarily sold for about one shilling the Hundred, but if remote from a great town, it
may be had for sevenpence.'

After another war (1921), rough wood sold at 25*. a load, with los. for cartage from Bagley or
Radley, retailed as wood blocks at is. per cwt., or is. a bushel of 50 Ib.

8 Plot, I.e., p. 267 : sold ' to the meaner sort of people ' by the Braid of 4 poles.

54 Plant-life of the Oxford District

In the former case, scarcely dignified as High Forest, large trees are
grown in open canopy for timber and billet-wood, the undergrowth of
minor trees being reduced or absent, as the last stage of residual standards
or overwood. Trees were extracted as required, and regeneration appar-
ently left to nature, as the last went. In such case a high light-canopy
was long maintained, and the herbaceous ground-flora remained under very
uniform conditions. Suggestive examples of tall-coppice are retained at
Bagley (Middle Copse, Milestone Piece), Sidlings Copse (Wick), Marley
Plantation (Wytham), and Stow Wood. The character of the undergrowth
varies with the nature of the trees of high-forest : under Oak it becomes
mainly Bracken and Brambles. Under Beech the ground is practically bare
(Wytham).

Underwood expresses wooded areas growing minor trees, more definitely
cropped in a rotation of 9-10 years or more ; the old stools being allowed
to regenerate, and the gaps made good by replanting. The trees are
utilized for poles, hurdles, fuel, bean-sticks, and a large number of subsidiary
purposes.1 This includes minor copses utilized for agricultural necessities,
and large areas of residual woodland (Bagley Wood) are still in this condi-
tion. The state of the underwood varies according to the main crop,
whether pure or mixed, and the nature of the soil. The growth of the
herbaceous ground-flora also varies with the main-crop and the water-content
of the soil, and is considerably affected by clear-felling and the first years
of regeneration. Where the canopy is closely maintained and there is little
water-content, the ground-flora may practically disappear; this being the
ideal of the forester.

Admirable examples of the difference in classes of underwood are afforded

by tracts of Bagley Wood, of comparatively recent planting.2

(1) Sycamore coppice, giving clean-grown poles (25 ft.). The summer
canopy is particularly dense, and the undergrowth gives nothing but a fairly
pure growth of Scilla nutans, flowering before the leaves are on the trees.
(Felling commenced 1922 ; previously cut 1895.)

(2) Alder coppice, at an optimum on the sides of damp gullies, giving clean
pole-growth, 30-40 ft., very different from the stunted trees of river-margin
and swamp-ditches. The undergrowth is mainly ferns (Pteris and Lastraea
dilatata\

(3) Birch coppice, on gravel and drier soils, giving similar tall poles and
light canopy (40 ft.) ; the undergrowth being chiefly Bracken.

(4) Willow and Poplar coppice, on swampy bottoms of alluvium or clay,
covering a damp undergrowth of Pteris, Nettles, and Mercurialis (Bottom
Copse, Bagley; Headington Wick Copse). Cut also in 9 years rotation, cleaned
and re-set

Osier beds give a special case, at an optimum on irrigated land, and cut
with annual cropping, in close-tufted growth which admits of little undergrowth.
Local examples are very poor.

(5) Hazel coppice is widely distributed; the low trees with surface-root
system doing well on clay where little else will grow ; examples on Kimeridge

1 Woods (1921), The Rural Industries round Oxford, p. 79, Underwood Industries. Under-
woods are sold or auctioned to small dealers for cutting (leaving the standards) at so much the pole :
cf. (1921) Nnneham Wood of good trees, cut at 12 years, sold at is. gd. per pole, giving fine poles
to 20 ft. of Birch, Poplar, Maple, Chestnut, Oak and Hazel. Faggots find a ready sale at 6d. each.
After paying for careful cutting, to avoid damaging the stools, and transport, there is little profit in
the business. Radley Great Wood, of poor stag-headed Oaks with Ash and Sycamore over Hazel,
sold at lod. per pole. Brasenose Wood of poorest Oak over thin coppice at 6d. per pole, =^4 per
acre. Bagley Wood, old Oak coppice, cut 1921, 1922, fetched £6 per acre.

2 Bagley \Yood was enclosed about 1840 ; hedges were made delimiting the roads, tracts in the
woodland cleared as rides, and the whole reorganized. These various coppices apparently represent
plantings on areas cleared at that time, together with many isolated patches of Larch, Spruce,
Chestnut, etc., making good gaps in the general canopy. Later plantings of Larch, and Forest
Plots (1907), follow the lines of more modern sylviculture.

Woodland and Copse 55

Clay (Bagley Wood, Spring Copse, Bottom Copse), and on Oxford Clay (Noke
Wood). Cut in 9 years rotation it gives remarkably clean straight basal shoots
as poles and slender rods. It was formerly much in demand for wattle hurdles,
etc. When neglected it fills up with Rose Briars and Brambles ; the stems
becoming irregular and forked are only good for faggots. The summer canopy
is dense, and the ground flora is restricted to spring-flowering Anemone, Scilla,
Ficaria, Mercurialis, etc., often very beautiful.

(6) Oak coppice, yielding durable poles and fuel, is the most characteristic
type and general case. Cut normally on a lo-year rotation, but now often
much neglected and running to waste at 20 years, owing to reduced demand
or expense of conversion.1 Large tracts of Bagley Wood remain in this
condition, with little change since mediaeval times.2 The stools are left
knee-high, and regenerate a close tuft of laterals, several of which may make
good poles; the stools being spaced at a distance of 3 yds. apart. Where
the growth is uniform and vigorous, a dense canopy will be maintained ; and,
where dry, little undergrowth of any sort is left, the ground being covered
with persistent dead leaves. But on clearing, a rich undergrowth of herbaceous
types is met with in the first few years of regeneration. It is open to invasion
by berry-bearing forms (Rosa, Rubus, Viburnum Lantana), and commonly
shows admixture of other trees, cut at the same time and similarly regenerating
from stools (Ash, Willow, Hazel): cf. Kennington Clearings (1920-22),
Underwoods.

The most general type of older cultivation is included as Coppice with
Standards, as an attempt at the combination of the two preceding cases,
which may also be regarded as limiting stages (early and late) in this type
of growth. A few trees may be left to grow on when the main underwood
is cleared, just as a few trees are often similarly left when hedges are
trimmed ; and these are allowed to persist over several fellings. The
method follows a natural process of evolution, and has been convenient in
the past, as the demand for underwood material and fuel was thus pro-
portioned to the smaller requirements of a distinctly agricultural community.
From the standpoint of the latter it has many advantages in utilizing waste
land; but otherwise the method is uneconomical. An isolated standard
tree completely destroys the regeneration of the underwood over a light-area
marked by its canopy, and the active regeneration of the underwood beyond
this area checks the water-supply of the standard. The canopy of the
whole coppice becomes discontinuous, so that both types of tree are
injured. Thus, where standard Oaks are left in Oak-coppice, the former
become stag-headed at the level of the underwood-canopy, with short bole
(15-20 ft.) ; light is admitted under the loosely spreading branches sufficient
to supply a colony of Bracken beneath the standard. The same effect is
observed when standard oak is left in Sycamore-coppice, and the injurious
effect on the crop is still more marked when residual oaks are left among
Larch and Scots Pine.

Remarkable examples of this class of coppice are left at Bagley, where
old stools of indefinite antiquity, moss-covered and moribund, give underwood
in stunted growth, 10-12 ft. high only in 20 years.3 Interesting cases of
regenerated 'standard' Birch among Larch and Weymouth Pine give trunks
1 2 in. diam. and several (5-6) from one stool.

Where well-grown, coppice underwood of Oak, close-planted areas of
Larch and other conifers, or coppice under standards, gives no herbaceous
ground-flora at all. The residual tall-coppice, however neglected from the
standpoint of the forester, affords with its scanty canopy, the best collection

1 Woods (1921), loc. cit., p. 83, foot-note.

2 Plot (1705), p. 267, gives 7-8 years rotation ; also 20 years for Wychwood Forest.

3 This ancient stool-coppice was probably planted in the seventeenth century, when fuel became
scanty. Otherwise there is nothing in the wood over 200 years old.

56 Plant-life of the Oxford District

of plants of the underwood botanically ; and in virtue of its very neglect
sylviculturally, is most suggestive of the original condition of the indigenous
woodland, when the trees of high-forest had acquired full dominance.

From the point of view of the sylviculturalist, the dense herbaceous under-
growth is not only useless, but is to be regarded as a growth of noxious weeds,
as are the weeds of arable land to the farmer or allotment-holder. To grow
trees alone, the entire area should be cleared of Brambles, Bracken, and all
herbaceous forms, and underplanted with Beech, to leave a floor-covering only
of dead leaves and humus ; in which case the indigenous flora would vanish,
or be left only as vestigia in hedges, ditches, and rides. Much of this type
of woodland at the present time has gone too far to be worth saving, and is
valued chiefly as a covert for pheasants.

Oak-coppice on good ground is supposed to last for ever ; on poor ground
it begins to fall off after 100-150 years. The old moss-covered stools at
Bagley, in the last stages, some merest shells, may be 200-300 years old,
giving regeneration-shoots in irregular dwarfed growths, which are but a cari-
cature of an oak-tree.

The custom of clearing underwood, and 'drawing' tall-coppice and
standards, which has been going on for at least 500 years, with no return
whatever to the soil, must have had an appreciable effect on the mineral and
especially phosphate-content. If pastures which have been long grazed are now
found to require superphosphate and basic slag, the same should apply with
greater force to the neglected woodlands, the food-supplies of which have been
apparently assumed to be inexhaustible. Stag-headed Oaks are devastated
by the Tortrix Moth, and regenerating underwood badly mildewed. It remains
to be seen to what extent matters can be improved by clear-felling the older
wood and replanting with Larch and Douglas Fir or other Conifers.

Following the importation of coal by barge (the Birmingham-Oxford
canal completed in 1790, and still used for the purpose), the importance of
copses as fuel-supply was much diminished, or such material was left to
people beyond the urban area. Present examples are hence much reduced
and neglected, or are only utilized for purposes of game and investigated for
rabbits. The ground-flora fills up with small underwood, often becoming
almost impenetrable, with thorns, sloe, brambles and briars. Especially on
dry soils this degenerates to a condition which cannot be distinguished
from regressive thorn-scrub (Bagley, upper West Wood, Hutchcomb
Copse).

In damp areas, as on the alluvial flats, Willows (Salix alba, S.fragilis)
were similarly utilized and planted as sets (10 ft.) along the sides of streams
and ditches. When pollarded, these assume a mop-headed brush-effect
which gives a characteristic appearance to the flood-level landscape, and
affords a case of special biological interest.

No special rule is observed in pollarding. Shoots may be cut at 2 years
for bean-sticks, as growth in the first year may be 6 ft. Larger poles 20-30 ft.
are obtained in 10 years. Neglected trees may be pollarded and then left to
grow out indefinitely (' Mesopotamia ').

All pollarded willows become subject to attacks of Fungi, and are ulti-
mately destroyed. After pollarding, strong new shoots send down roots of
their own, descending under the bark of the old trunk to the soil. The
original trunk, always decayed by Polyporus attack, infecting from the wounds,
ultimately becomes a mere hollow shell, and the functional head of the tree
stands on pillar-roots which are only revealed by tapping or slitting the bark.
In a further stage the old shell splits with the increase of new ' stems ', falling
asunder in 2-3-6 ' split Willows ', each supported on its own divergent
trunk, or falling over if not strong enough. A willow can be so pollarded
half a dozen times before badly decaying: they become hollow shells in
50 years.

Woodland and Copse 57

The bushy growth of green shoots after pollarding, and the collection of
wind-borne debris between the old stumps and decaying twigs, affords a
nidus for all sorts of seedlings to germinate, often with conspicuous success,
as a flora of humanly assisted epiphytes. Minor plants as Taraxacum,
Aquilegia (3 ft., and 60 flowers), Senecio squalidus, thus flower and fruit on the
heads of the trees, with roots sunk deep in the decaying central mass. ' Epi-
phytic ' brambles and briars may send their roots down to the soil inside the
trunk, and hang as lianas from the upper branches. Woody forms follow
the same course, and well-grown bushes may be found in Willow heads (jRi'&es,
Elder, Viburnum). The limiting case of a Pyrus Aucuparia, 20 ft., was noted
near the Botanic Gardens ; but these are cut away in the pollarding rotation,
and their further development is checked.1

Forest Plots and Clearings. In all cases of clearing and felling, or of
coppicing and planting, the effect of human agency is directly obvious, and
the ecological interest centres in the recovery of the ground-vegetation,
as much as in the regeneration of the woodland main crop. Beyond the
general exploitation of the woodland included as Forestry, Sylviculture is
concerned more particularly with the regeneration of the woodland and the
growth of some special form of tree. As in the case of agriculture, this
involves a weed-problem, as other plants require to be kept in a subsidiary
position, or preferably wholly eliminated. On the other hand, the ordinary
agricultural methods of ploughing, cultivating, manuring, and sowing,
involving considerable labour and expense, when operations are conducted
on a still larger scale, are commonly ruled out. Regeneration is thus left to
natural causes, or forest-land has to be planted.

Older methods of forestry as cultivation of coppice with standards, or their
limiting cases,2 in past centuries, express the retention of a practice introduced
from the continent, and still largely followed in France, which aims at the
supply of the needs of a countryside with a cheap source of fuel, as well as
agricultural timber and poles. For these purposes the underwood is cut in
rotation of 8-10 years or 15-20 years, often before the trees flower and fruit.
As such coppice is not everlasting, although oak-coppice endures a long time,
for purposes of regeneration a few standards are left at intervals to supply the
necessary seed. In such case regeneration is left to nature, the underwood
is cut with one rotation, e.g. 10 years, and the standards are given a rotation
of possibly 100 years.3 The application of the system, however otherwise
objectionable, is seen in the fact that natural regeneration is provided for from
the first ; and in the case of an indigenous tree, a dense crop of seedlings will
keep down intrusive weeds as herbaceous ground-flora and grasses.
More modern forest- practice may differ in that : —

(1) The tree favoured as main crop may not be an indigenous form
at all, but one giving a greater or quicker return of timber, or one which is
cheaper in production and conversion, as also commanding a better market.

(2) The woodland may not be grown for local needs at all, particularly
in a country where there are other sources of fuel, and the crop may be so far
a commodity for export.

Both cases' are admirably illustrated by the general cultivation of Larch
poles for mine-work (pit-props).

In such case the regeneration cannot be left to natural causes ; that is
to say the forest requires to be planted ; while, as the trees when young are
less likely to compete successfully with the indigenous flora, the ' weed '-problem

1 Plot (1705), p. 173, records the case of an Ash which grew until the Willow shell was left as
relic : a good Elder tree (15 ft.) on a Willow at Wolvercote, 1922.

For a list of 60 species of plants noted 011 Willows at Oxford, cf. Gunther (1912), Oxford
Gardens, p. 259. Other trees are less frequently pollarded, but an Elder (5 ft.) grows on a Sycamore
which has been formerly pollarded, at Godstow.

2 Schlich (1910), Manual of Forestry, Silviculture, ii, p. 106.

3 Schlich, loc. cit, p. 105.

58 Plant- life of the Oxford District

arises, and the plots require a certain amount of attention in early stages.
Hence in the cultivation of such a form, seedlings have to be raised in a nursery,
planted out in an early stage of growth, and the rapidly growing weeds and
intrusives kept down by methods of cleaning.

In general practice young plants from the nursery are planted at 4 ft.
apart each way, to grow to uniform pole-height, before thickening the main
trunk ; and by making close-canopy these may effectually dominate the ground-
flora in the course of a few years. Full dominance is only gained in 10 years
or so. In the first years after planting, the ground-flora may be more con-
spicuous than the crop ; the spaces regenerating Bracken, Brambles, and a large
supply of intrusive grasses, unless these are periodically cleaned and cut out.
All such cleaning and early thinnings add to the expense of production ; and
the age of the crop for felling, simultaneously as a crop, has to be adjusted by
financial considerations in order to make it pay. A continuous output is
maintained by a succession of plantings, involving successively maturing tracts
of such woodland.

As local examples of such methods may be distinguished : —

(1) Clearing of Oak coppice? allowing free light-supply to the ground-flora,
but with effects of increased desiccation owing to the loss of the damp canopy.
Xeromorphic forms become more conspicuous, with a wide range of intrusives
from dry situations, giving a greatly increased variety of species (60-100);
Kennington underwoods, Oak-stools at 3 yards apart.

With the growth of the coppice- regeneration after 4-5 years, these in turn
dwindle, shade-plants become more numerous, and in 8-9 years the effect of
a shaded woodland, largely restricted to spring flowers, is again produced.

(2) Clearings of more modern forest-practice, involving clear- felling of older
woodland, and replanting with a crop of deciduous Larch, either pure or
subsequently underplanted with Abies or Beech; the trees being planted at
4 ft. From the examination of plots of different ages, it is possible to visualize
at one time the successive stages of succession ; and the general effect as
the control of the ground-flora expresses the success of the working-plan.
(Sunningwell Bottom, Milestone Piece, Bagley Wood.)

Good examples are afforded by the experimental plots of the Forestry
School at Bagley Wood. Such plots are however subject to periodic cleaning,
with removal of the larger intrusive shrubs, bracken and brambles, as also the
thinning of the main crop and removal of dead laterals.

Cases of special interest, followed in such forest-plots, are observed as the
main crop involves a tree-form which may be evergreen, or distinctly alien,
or no longer indigenous, and its relation to the general ground-flora. Such
plots include Pinus sylvestris, Pinus Strobus, P. Laricio, under which, when
planted at 4 ft., the canopy is so dense, and the ground so covered with a
carpet of needles (2-3 in. deep), that nothing whatever grows, as soon as the
canopy is attained. The same applies to Pseudotsuga and Thuya plicata with
still darker canopy : in the last case, with deepest shade, the floor is a dense
carpet of dead phyllomorphs, through which not even a residual Scilla pierces.
Pfnus-cznopy opens out after 20-25 years.

Under Larch, however (European, Siberian, Japanese), owing to lighter
canopy in summer, and the deciduous habit, the undergrowth at first may fill up
with Bracken, which when left uncut,2 is the agent more particularly concerned
in keeping down all lower ground-flora. Brambles may long continue ; but the
carpet of needles is at length only varied by a few stray plants of Ajuga,
Teucrium, Scilla, etc. (20 years). On thinning, and growth to higher canopy,
at 30 years Larch-plantations may again give Bracken undergrowth as light
penetrates, and should be under-planted.3 The crop matures at 60 years
or more.

1 Schlich, loc. cit., p. 341.

2 Owing to want of labour during the years of the war, many of these tracts were much neglected,
and are not to be taken as fair samples of sylvicultural treatment.

8 Schlich, loc. cit., p. 404.

Hedgerows and Hedgebanks 59

Hedgerows and Hedgebanks. The use of some sort of barrier, whether
wall, hedge, or ditch, delimiting property, as land isolated for some special
purpose, or for preventing cattle from straying, would appear to be a natural
commonplace of human occupation. Walls and hedges may play a subsid-
iary part in a local flora, the more conspicuous as the plants are usually
elevated to a position in which they attract the eye ; and these formations
afford a wide range of secondary biological stations of particular interest.

(1) The masonry wall of squared cut stone (ashlar), or of rough
rag-stone from the Limestones of local Corallian or Portland beds, soon
affords a nidus for intrusive rock-plants, germinating in cracks of the
stonework, following mosses and lichens which obtain water from the damp
stone, the more conserved internally as the outer surface may be impervious,
and channels follow the lines of rain-drip. Walls built of the eminently
soft, porous, and rapidly weathered free-stone from the older Headington
quarries, soon develop a flora of a few grasses and larger flowering plants,
of which the most conspicuous are

Senecio squalidus? (Dianthus caesius)?

Hieracium murale,2 Snapdragon and Wallflower.

Only very exceptionally in this district do old stone-walls carry small
ferns : —

Polypodium vulgare, Cetarach officinarum,

Asplenium Ruta-muraria, Asplenium Adiantum-nigrum.

(2) Rough rag-stone walls of farmsteads, gardens, etc., with or^without
mortar, acquire a moss-layer, soon giving a coating of fine soil, which may
carry a miniature crop of Draba verna in early spring, followed by a special
flora of diminutive forms (Iffley, Hinksey, Horspath, Headington) ; cf. : —

Senecio vulgaris, one inch high, reduced to one terminal capitulum.

Valeriana olitoria, -| inch.

Arenaria serpyllifolia, 10 mm. high, reduced to one terminal flower: also —

Linaria Cymbalaria, Poa annua,

Crepis taraxacifolia, Sderochloa rigida.

These tend to wholly disappear as summer heat shrivels them ; and only
specialized xerophytes retain their stations : —

Sedum acre, Saxifraga tridactylites^

Sedum reflexum,

Sedum dasyphyUum^
with starved forms of grasses as —

Festuca bromoides^ Hordeum murinum,

Poa compressa, Bromus sterilis ;

and more casually, Corydalis lutea, Linaria purpurea^ Centranthus ruber,
Verbascum Thapsus, with more definitely alien Cheiranthus, Antirrhinum,
and obvious garden-escapes as Arabis alpina, Arenaria, Alyssum, and
planted Sempermvum tectorum.

(3) The case of the rough stone wall grades naturally into that of the
hedgebank built more or less of a mixture of stones and earth, as a station
with considerable possibilities from light-exposure ; but subject to reduced
water-supply as the summer advances, — ultimately becoming wholly dry
from above. On such hedges the spring vegetation may be abundant ;
but later in the season they show little more than the usual associates
of waste-places and rubbish heaps, with no special characteristics of
their own.

1 Hence commonly known as the ' Oxford Groundsel ', the bright yellow flowers of which have
been seen on the Examination Schools (erected 1882), on the Radcliffe Camera and many old
buildings and College walls : on the Town Hall (built 1897) immediately following clumps of moss.

2 On old walls, Lincoln College, Blue Boar Lane, often very conspicuous.

* Residual on wall of Wadham College, and St. Hilda's (once Sibthorp's residence).

60 Plant-life of the Oxford District

(4) The true Hedgerow, as generally understood, is a more complex
construction, as an earth bank separating fields, etc. ; the material used to
build the wall being taken from the ground level, and leaving a ditch-
depression at its foot, which subserves drainage ; while arborescent forms
are planted as shrubs or small trees on the top to increase the obstruction
to cattle or human beings. Such a hedge is required to be strong enough
to keep a bullock from thrusting through, or a horse from jumping over.

The characteristic hedge is built from sets or seedlings of spinous
Hawthorn (Crataegus monogynd). Trees may be subsequently encouraged
in such a hedge, as affording casual shade for cattle, and for utilization as
rough timber ; these being left to grow on as standards, when the thorns
are periodically trimmed. The leaves shed from the deciduous shrubs
accumulate in the hedge-bottom, as a humus-soil which may be of no
great thickness, but serves as a nidus for a large collection of woodland
plants, together with many intrusives from waste places.

The hedge is in fact a miniature edition of woodland, but regressive
and artificial rather than vestigial. The upper part may epitomize standards
with coppice, as the wet ditch may recall swamp- woodland, or the grass and
herbage of the sides a mixed pasture. The wooded portion has been
commonly so treated by the agriculturalist, with suggestions of an under-
wood rotation and the felling of standard trees ; while the herbage may be
cut in the manner of hay for fodder and bedding. It is, in fact, this character
of presenting a sample of all types of country vegetation which makes these
structures so characteristic of English scenery, and so interesting botanically.
In the course of years, such hedgebanks attain a considerable size, and take
up a considerable proportion of the land under cultivation. The standard
trees, for example, may affect planted crops injuriously for a distance much
farther in than that of their leafy canopy (to 50 ft.). Hedges may consider-
ably add to the aesthetic aspect of the landscape, but economically they are
unsound, and often a nuisance. On the whole they are to be regarded as
the survival of a past epoch.

The formation of hedgerows is of comparatively modern growth. In
mediaeval England, beyond fences and walls around gardens and orchards,
there were practically no hedges. Under the feudal manorial system of
land-occupation, the greater part of arable land was worked in common under
the Lord of the Manor, only fenced in when the crops were standing. Beyond
the more cultivated tracts was open common land, including waste and
woodland, where this last was not a part of a Royal forest preserved for
game.

Hedges delimiting smaller tracts of land came in with the decay of the
feudal system, and after the Wars of the Roses, with more particularly an
increased output of cattle and the beginning of an improved agriculture. Such
enclosures of arable land, thus manured for growing corn, as field-units
specialized for different agricultural work, increasing from the sixteenth to the
eighteenth centuries, encouraged the small-holder, and led to the system of
farming which has continued to the present day. It must not be confused
with the enclosure of open common graztng-gTound and waste-land for cattle
and sheep-runs, which was a fruitful source of rioting on the part of dispossessed
peasantry from the fourteenth century to the present time.

It would appear that hedges were constructed primarily with a view to the
needs of stock-raising ; and their persistence and prevalence indicate a district
given over to cattle-rearing rather than to cultivation of cereals. From such
a standpoint the advantages of hedges are obvious, as they are numerous
(Fitzherbert, 1523, Book of Husbandry, and The Book of Surveying). They
may be regarded as a more permanent extension of the method of folding sheep
with hurdles. Cattle-herds were dispensed with ; small tracts of land could be
grazed and intensively manured without damaging and trampling the whole.

Hedgerows and Hedgebanks 61

The available food-supply was thus brought under control, grazing cattle were
given shade and protection from storm and cold, while the small farmer was no
longer penalized to the advantage of the larger owner on the common land.
The tree-material, again, furnished a local supply of small fuel, near at home,
and compensated the disappearing woodland.

On the other hand, hedges entail considerable skilled work in construction
and maintenance. The original use of a thorn-fence of ' quicksetts ', implied
cutting, trimming, and interlacing to a typical fence of 4 ft. in height (impene-
trable by cattle), which has had much to do with the evolution of steeplechasing
and hunting in central England.1

Even a thorn-fence requires careful attention. Though the Hawthorn is
the most enduring tree of the countryside, it cannot be cut indefinitely. When
pruned to a neat and constant form by ' removing the spray ' of annual shoots,
the plants will deteriorate in time. Hence they soon require to be left to grow
out for a season or two to recover vigour. If this happens to be neglected, the
plants grow to bushes, with admixture of intrusives which may soon become
dominants. Deteriorating still further, the thorns are cut back to stumps, with
a rough rotation of 10 years or so; the hacked and split stools make an
indifferent recovery, and the majority of hedges of this class are now mere
wrecks, or in any case, something quite different from what they were originally
intended to be.2

As pasture-land thus devoted to stock again becomes utilized as arable,
hedges tend to disappear, being valueless except as wind-breaks in exposed
situations, and the fields may be delimited by wire fences. But the more recent
application of barbed wire is the limit.3

When allowed to vegetate quite freely, the thorns attain a height of
20-25 ft, affording a canopy as many feet wide. A rank growth follows in
the drip of the end-branches, which then becomes the limit of the field-area,
whether pasture or arable. Coarse grasses, nettles, brambles, and briars
grow up to meet the canopy of the thorn, giving a continuous mass of foliage
as a screen to the ground-level ; and this as the hedge-base affords a station
for a wide range of herbaceous forms, graded according to their height
and the distance to free light-supply. Hook-climbers and tendril-climbers
interweave in the mass, or clothe the upper levels. Within the more shaded
central tract, vegetation is checked and may wholly disappear, giving a
tunnel-effect, with the original thorn-trunks in the middle line, as a run for
dogs and small boys. Gaps in the outer canopy of brambles and thicket
allow cattle to utilize the tunnel-portion for shade and shelter. Large trees
allowed to persist as standards, especially the Common Elm, as intrusives,
less frequently Oaks stag-headed at the brushwood level, afford a dense
canopy, ultimately suppressing the thorns, and leaving gaps in the fence.

1 The neat professional thorn hedge, trimmed 4ft. high, and interlaced obliquely (plashed),
affords little scope for intermixture with intrusives until it is badly neglected, and allowed to grow
out. A county instructor in hedging is now employed by the County Council.

2 The most interesting trimmed hedge locally is the remains of the ancient thorn fences bound-
ing the path raised above flood-level between Wytham and Godstow. Double hedges of thorns
planted 5 ft. apart, and more or less neglected, give a peculiar tunnel-like construction in meadows
above Wolvercote. Thorn fences of Bagley Wood date to about 1840, those bounding the Railway
Line to about 1 850. Such hedges, once carefully kept, are seen in all stages of neglect and decay
in the fields absorbed within the urban area (Cowley), reducing to a single line of residual standard
thorns (25 ft.), these then more and more isolated, or left as stumps against which cattle rub.

3 Barbed Wire, a product of the evolution of the Western cattle ranches of America, has been
manufactured since 1874. The initial cost is comparatively small, and it is practically indestructible
if the supports are also of steel or of reinforced concrete. Cattle avoid it, and it solves the weed-
problem of the hedges. It is also almost invisible in the landscape, but it affords no shelter from
wind or sun. Legal restrictions so far (1893) apply only to the possibility of damage to persons or
cattle lawfully using the highways. But the country walk of the future tends to be restricted to
a straight and narrow gangway between two lines of barbed wire (cf. path from Headington to
Shotover Hill). A graceful finish is given by tacking a strand over the top of any gate at which one
might wish to stop to admire what is left of the view.

62 Plant-life of the Oxford District

As nothing lives long in the shade of a big tree, a gap can be always
located near a tree trunk ; such gaps require constant mending, and are
commonly made good with a generous use of barbed wire.1

Such hedgerows with great range of biological factors, free insolation,
good drainage, and damp bottom, carry a correspondingly wide range of
types, which defy analysis, until it is realized that the assemblage is purely
artificial, and that all the forms are competing according to their special
requirements and capacity for getting there. At their optimum these
hedges present all the phases and features of regressive woodland, the
initial thorn-fence is as often lost to sight, as it is only traced in historical
development. The larger trees of high-forest afford shelter and humus
for woodland undergrowth ; grasses and herbaceous plants of the pastures
extend to the lower levels. Tangled lianas add to the jungle-effect, and
subaquatics may flourish in the ditch. Forms with deep-running rhizomes
and roots send up aerial shoots extending along the length of the mass.
The flora of such hedgerows constitutes a special feature of any agricultural
district, and locally may include over 100 forms taking part in the annual
succession.

From forest-trees (Oak, Ash, Willow, and particularly Ulmus campestris,
running its soboles along the hedge-line), to minor woodland forms, Hazel,
Sallow, and woody shrubs growing from berries brought by roosting birds
( Viburnum Lantana, Cornus, Ligustrum, Rhamnus catharticus, Prunus spinosa,
Pyrus Malus, and especially Sambucus) to scrambling forms as Rosa, Rubus in
variety. Climbers include Solanum Dulcamara, Calystegia, Lonicera, Humulus,
Bryonia and Tamus, to Galium Aparine, Vicia Cracca and Galium Mollugo.
Larger grasses push through, as Dactylis, Arrhenatherum, Bromus asper, Br achy-
podium sylvaticum, Agropyrum repens. Herbaceous forms follow the annual
succession — Alltarta, Anthriscus sylvestris, Lychnis dioica, Geranium robert-
ianum, Stachys sylvatica^ etc., to more xerophytic summer flora of Heracleum,
Pastinaca, Daucus, Carduus (sp.), Rumex (sp.), Senecio Jacobaea, and Hel-
minthia echiotdes. Special cases of deep-travelling rhizomes give hedgebanks
in damper situations dominated by Spiraea Ulmaria, Epilobium hirsutum,
Equisetum Telmateia, Phalaris arundinacea, and Phragmites communis.
Examples of such formation afford interesting studies for more detailed
ecological examination, as each station requires to be taken as an indepen-
dent complex with special factors of soil and water-supply of its own ; as
also of the nature of the surrounding associations which supply the initial
equipment.

(5) The case of the Hedgebank, as a deep road-cutting, where the road-
gradient has been lowered, is less general in a flat country. It differs from
the preceding by being backed against solid ground with assured water-
supply. Such banks carry a more abundant flora ; and where shaded may
retain the characters of damp woodland, with characteristic woodland forms
(Primrose, Violet, Melica nutans, Malva moschatd). (As a minor example,
cf. Kennington Lane, 'Little London', until recent times a woodland track.)
Such banks grade into the case of the railway-cutting, where this is
deep and wide enough to be left to something beyond mere grass (Little-
more, Horspath). On Corallian strata these carry an abundant flora, and

1 Barbed wire entanglements fill gaps so cheaply, that good hedging tends to vanish ; but the
wire when rusted and concealed in later growth, is dangerous as well as objectionable. Though the
use of barbed wire tends to increase nearer the town, the condition of the hedgerows affords a good
test of the quality of local husbandry. In the more open country, the neat thorn-fence is dominant,
and often remarkably so. Where deteriorated and ruined, the original thorn-stumps can be generally
traced among the overgrowth ; substitution of Prunus spinosa in exposed areas, or Myrobolan Plum
around garden-tracts, gives no better results. The most destructive intrusives are Elder, Hazel, and
Common Elm; the two last run lengthways in the fence, and may in time wholly dominate it.
Minor garden-hedges of Privet {Ligustrumjaponicuiri}, Yew, Beech, Cupressus Lawsoniana, Holly,
attain a decorative value as they are kept constantly clipped and clean.

Hedgerows and Hedgebanks 63

may tend to regress to woodland shrubs ; but they are subject to destruction
and intentional clearing by fire.

The case of the embankment is more artificial, since the material is
largely gravel-ballast, well-drained and exposed to considerable desiccation
in summer. The vegetation is usually particularly luxuriant and advanced in
early summer ; but is also subject to cutting and intentional or accidental
destruction by firing in the dry season, with consequent wholesale renewal.

(6) As a converse case, the hedge and ditch in the alluvial area tends to
be replaced by a ditch only, and the latter subserves drainage as well as
acting as a barrier to cattle if deep and wide enough (6-10 ft). The
material taken from the ditch is used to increase the height of the sill. Such
ditches are then connected in an irrigation system, linked up with the larger
streams, and not only take away flood-water, but will retain standing water
over long periods of drought. They hence become secondary stations for
abundant aquatic types, enriched by surface-drainage from the pastures with
animal-droppings, and again give a wide range of flowering plants, as a
special meadow-ditch flora of about 100 forms (cf. Iffley Fields, Marston
Meadows, Hinksey, Botley), quite distinct from those of the adjacent pas-
tures, though subject to a certain amount of overlapping, as typical ditch-
plants may be intrusive in the damp pasture and arable land (Phragmites,
Eqtdsetum^ Polygonum amphibium) ; while the pasture-weeds may encroach
on the ditch margin (Carduus arvensis^ Rumex crispus). Characteristic
plants are Spiraea Ulmaria.Epilobium hirsutum, Valeriana(sQ.), Mentka ($$.)>
CEnanthe fistulosa, Nasturtium amphibium^ Myosotis palustris, and in or by
deeper water, Scirpus lacustris, Sparganium, Sagittaria, Butomus, Sium lati-
folium, Alisma Plantago^ Rumex Hydrolapathum^ with numerous large
Carices (C. riparia, C. pahtdosa, C. vulpind) ; also Hottonia, Hydrocharis>
Lemna and Myriophyllum in the water.

All these types of Hedge-formation acquire special interest from obser-
vation of the relation of the annual succession to their water-supply, which
remains the local limiting factor, since temperature and light may be taken
as fairly uniform : as also from the standpoint of succession in time, as the
particular formation is initiated, and in the course of several seasons attains
its special character. It must be noted that the constancy is largely main-
tained only by human agency, and that all are subject to the possibility of
human interference and destruction at any time ; asshedges may be trimmed
or wholly demolished, and ditches may be cleared out, drained off, or filled
up again. The common type of mixed hedgerow is subject to a rotation of
a definite number of years (averaging 10), to prevent too great invasion or
shading of the field-area, or to supply brushwood for fuel. Hedging and
ditching becomes skilled agricultural labour, and is too often a lost art. The
inferior types of hedge, as indicative of a deteriorated condition of husbandry,
are the stations most let alone ; the examination and observation of the
biological factors of a ' hedge ', and the phenomena of its annual succession,
progression, or retrogression, afford good exercise in floristic and ecological
instruction, and further examples may be taken in detail.

Regressive Woodland.

Woodland areas, cleared of all standing timber, and regeneration pre-
vented, as by paring and burning, become an open clearing in which the
original humus-flora of the woodland-base soon deteriorates, and may be
completely destroyed on exposure to the desiccation of summer sun ; the
more quickly on clay tracts in which the soil may be badly cracked. With
the addition of intrusive weeds of dry pastures, the soil soon reverts wholly

64 Plant-life of the Oxford District

to mixed grasses, with Juncus in damper spots, and such open rough
grazing land was particularly developed in Mediaeval England, becoming
the general formation of waste common land ; controlled by keeping
down all attempts at woodland regeneration, giving material for faggots
and fuel, or intrusive Bracken and Furze kept down by firing, and so
maintained indefinitely, so long as grazing for horses and cattle was the
dominant factor.

On enclosure, or neglect of the original use, such land rapidly changes
its appearance ; the larger perennial xerophytic forms, enduring the summer
heat, become predominant, and spring-vegetation of perennial habit may
grow above the grass-level especially favoured by rabbits and cattle.
Thorns, Brambles, and Roses take root : on lighter soils Ononis spinosa and
Thistles ; on heavy soils especially Crataegus, Rosa canina, and R. arvensis,
to be followed by Rubi, Lonicera, Prunus spinosa^ Ulex and Pteris. Where
cattle continue to graze, such spinous plants become centres of dense bush-
formation ; Brambles and Roses rise over the Furze-bushes ; cattle grazing
on the residual herbage work out grassy tracks between and around the
bushy growths, and the whole becomes a regressive rose-thorn scrub, which
will further grow on to an impenetrable thorn-thicket, dominated by Cratae-
gus and Prunus spinosa as these in turn rise above the level of the roses and
brambles, with an undergrowth of coarse grasses and Junctis retained wher-
ever light can penetrate. On these trees lianoid forms as Bryonia, Calystegia,
Solanum Dulcamara, and Lonicera give massed growths, the last flowering
freely at the top of the scrub (20 ft).

Among such thorn-scrub other trees may germinate and grow under
the damp cover, especially Acer campestris, Salix,Alnus> Fraxinusand Oak.
As these forms will all grow on above the thorn-zone, and the Oak is the
most enduring of all, the last stage gives poor oak-trees, stag-headed above
the level of the underwood : the latter, shaded out, is gradually replaced as
the canopy becomes dense, and Hazel may come in with increasing humus
in the damp bottom, with Elder in the dampest spots ; giving in time an
Oak-Hazel coppice, mixed with minor trees, which may be cultivated on
the coppice-under-standard principle, as the underwood is cut out, and
a few of the more likely-looking trees (Ash and Oak) left to continue at
successive clearings. In thinning it is evident that the generally established
older forestry practice, dignified by modern writers as ' Coppice with Stan-
dard V expresses the natural evolution of the countryside, satisfying the
requirements of peasant-proprietors, without any special forethought or
calculation ; however subject to further elaboration as the clearing periods
become more systematized.2 A woodland which has been coppiced or drawn
for several centuries is by no means virgin forest. Much of local woodland
is astonishingly poor in tree-growth, suggesting that the soil is wholly
exhausted, having been thus cut for many generations with no return what-
ever, or too recklessly exploited.

Good examples of this progression are still afforded by parts of ' Open '
Brasenose and ' Open ' Magdalen, grading to the later phases in Magdalen
Wood and Brasenose Wood, of poorest coppice on Kimeridge Clay. Much
of the older and more neglected part of Bagley Wood (Spring Copse) is little
better ; and this seems to be the general mode of origin of many small Copses,
which are probably not so much the retention of areas of primitive woodland, as
secondary regressions of partially cleared * waste '. Older woods are really as
artificial as the compartments of modern forestry practice; only the much-
enduring ground-flora has any claim to be in direct succession. -The last phase

1 Schlich (1910), Manual of Forestry, ii, Silviculture, p. 104.

2 Schlich, loc. cit., p. 105 ; age- gradations being more generally attended to on the continent.

Bagley Wood, Aug. 1922. Larch-plot with Pteris invading
bottom at 25 years.

a

V

£

JZ

"&

£

•3

In

Regressive Woodland 65

in which the overwood is allowed to become dominant * need not imply a history
of more than 100-200 years.

Admirable minor examples are afforded by the Hinksey ' Ravines '. These
represent deep erosions in Corallian strata, three in number, cut in lower parts
to the Oxford Clay bottom, to 50-100 ft. deep at the maximum ; the bottom
swampy, and the sides too steep to readily plough or mow. All were originally
well-wooded from top to bottom. The present state of these ravines (especially
that of the Chilswell Stream, or ' Happy Valley ') epitomizes the story of local
woodland. The swampy bottoms give /#«««-association, as water percolates
to the clay strata, residual copses are left in isolated patches (Chilswell Copse,
Limekiln Copse), but much of the sides has been cleared to be utilized as
rough pasture. The slopes show a remarkably clean-cut sky-line, and the
ground above (Coral Rag) is arable, and cultivated to the edge.2 The grassy
slopes tend to revert to thorn-scrub, which may regenerate poor coppice in
parts, but in others is kept down by bill-hook. In some more level lower
portions, small holders are beginning to struggle with the difficulties of the
situation. The 'Happy Valley' is within the range of school-holidays, and
is popular on Good Fridays and Bank-holidays.

(1) The Chilswell Ravine ('Happy Valley') is continued up above the
Kimeridge Clay at Chilswell Farm to the Greensand of Pickett's Heath,3 giving
a few distinctive plants in higher parts (Campanula rotundifolia], and poor
coppice on the clay (Birch Copse).

(2) The Rifle-range Ravine, north of Chilswell, passes up to clay, over
which streams exude giving good Hill-swamp of Equisetum Telmateia, and
subaquatics in profusion, with Eupatorium and Orchis maculata\ at a higher
level Juncetum, thorn-scrub, and on the Corallian characteristic thistles, as
Carduus acaulis and C. eriophorus, following on to the bottom of Hen Wood.

(3) The Old Rifle-range Ravine, south of Chilswell, is less deeply cut and
cleared. It similarly continues on to the Kimeridge and the derelict coppice of
Tommy's Heath to the Greensand of Boar's Hill.

Grassland and the Evolution of Pasture. ,

The original formation of grassland, as a special case of Herbaceous
plant -growth, follows as a general adaptation to conditions of reduced rain-
fall and water-supply, involving an amount available in the year less than
will support tree-life in close canopy. It thus presents a remarkable
example of adjustment to extreme seasonal change, originall)' expressed as
the alternation of a hot and dry period with a short rainy season in tropical
forest.

The Grass-type implies the total loss of the primary arboreal factors of
erected main axis with cambial increase and a deep-sinking primary root-
system ; the prototype being seen in Bamboos of High Forest, as a special
biological growth-form, running parallel with the liana in its capacity for
rapid rise to the top of the forest with minimum stem-material, but by a
wholly distinct mechanism. A tropical Bamboo may be rushed up 100 ft.
in a month of the wet season. The main axis reduces to a more or less
horizontal rhizome, giving off erected laterals seasonally, which show no

1 e. g., Oak over Hazel and Bracken, but also intrusive Common Elm over Nettles, or alien
Sycamore-coppice over Mercurialis.

Cf. Schlich, Silviculture (1910), p. 265. The stools of ash, maple, birch, and beech are short-
lived, lasting frequently not more than two or three rotations. Oak-stools are practically
indestructible, and Hazel freely suckers. Hence where there is little planting, Oak- Hazel coppice
becomes the end-term of an artificial selection, as a simple matter of survival.

2 Headington Wick, on the Elsfield side of the valley, is a similar ravine, cultivated to the
southern edge, but still predominantly coppiced.

3 The old hill-track to Wootton rises straight up the Chilswell valley from S. Hinksey, at 200 ft.,
to Chilswell Farm on clay at 400 ft., over Pickett's Heath (by Matthew Arnold's tree) to Hill-crest
(500 ft.) on the top of the Boar's Hill Road.

66 Plant-life of the Oxford District

secondary increase in thickness, but exhibit a marked telescopic growth-
effect by the intercalary extension of the internodes of a distichous phyllo-
taxis-construction ; the root-system being wholly adventitious from the
nodes, and utilizing surface-water.1

This short-season type, originally a forest-product, thus becomes the
colonizer of open country, or savannah-land, with exaggerated seasonal
effect (wet and dry), fruiting with a particularly short vegetative season, and
perennating where trees cannot subsist on small supplies of surface-water ;
hence passing with equal facility to reduced forms of xerophytic grassland,
or to the subaquatic life of the water-logged swamp. On migration to
North Temperate regions, smaller and more depauperated types become
the familiar vegetation of grassland, enduring winter frost and snow as well
as summer drought, vegetating freely over a short period of little more than
three months in the year, and utilizing their capacity for telescopic extension
for the erection of a short-lived and wind-pollinated inflorescence-system.
A closely parallel biological equipment is attained in quite distinct plant-
series of the Monocotyledons, as Cyperaceae, Juncaceae, and other families
with no direct relation to the Gramineae, to the extent that such forms
become characteristic of poor ground, sour water-logged soil, as residual
vegetation where little else will grow.2

Hence in the migrant flora of a North Temperate country as Great
Britain, grass may be taken for granted, as already established, and capable
of occupying open land beyond the forest-belt ; that is to say, where the
tree-canopy fails, grasses will become dominant, both on dry hill-sides as
xerophytic forms enduring extreme desiccation as dry turf, and in swamp-
areas as aquatic types mingled with reeds, rushes, and sedges of very similar
and convergent biological status. Though there is no direct evidence that
open grassland ever existed within the Oxford district, even on the tops of
the adjacent hills in post-glacial times, grassland undoubtedly prevailed on
the hills of the Chalk at no great distance. Since grasses grow freely where
trees will not, any clearing of a woodland area soon results in the production
of grassland, which is maintained so long as the woody forms are kept from
regenerating. Such grass-tracts by continual cutting, mowing, cleaning, or
burning, become the more emphasized, as further progression of the associa-
tion is closed, and the conditions for luxuriant grasses are improved ; since
all grasses, even the most enduring, flourish best in good well-drained and
aerated soil. By close- cutting at the soil-level, the majority of herbaceous
perennials may be kept down, and the grass-association is improved by
agricultural selection, giving the mantle of green turf characteristic of modern
pasture-land and even golf-courses. That is to say, the evolution of pasture
is the expression of the influence of human agency on the original tendency
to open grassland in the absence of trees, now extended to tracts with
better water-supply, fully capable of growing trees, but maintained arti-
ficially where trees have been denuded. The pastures become the more
artificial as they are mown every year at about the same date, levelled, and
the time of cutting adjusted to suit the periodicity of some grasses more
than others.

In allowing for the present condition of pasture-grasses, it must be
remembered that a long sequence of equally migrant races of men have
colonized the district, bringing with them domesticated cattle as bullocks,

1 Note that the erected monaxial Zea Mats, familiar as a ' typical Monocotyledon ', is a wholly
secondary expression derived by agricultural selection as a mutant of Euchlaena mexicana, the
multiaxial form of which is cultivated as Teosinte.

For account of the organization of Forest Bamboos, cf. Troup (1921), Silviculture of Indian
Trees, p. 990 ; Brandis (1911), Indian Trees, p. 660.

2 Schimper (1903), Plant-Geography, Eng. Trans., p. 591, General Oecology of Grassland.

Grassland and Pasture 67

sheep, and horses, all essentially grass-eaters, and thus adding to the factors
of the grass complex, as they may prefer distinct types of grass, — sheep the
finest, horses the coarsest, and bullocks the most nutritious. By close-
cropping the grasses they prefer, these animals encourage the growth of new
shoots, increasing the vegetative system below the dead herbage, and inci-
dentally supplying manure. To this may be added the question as to
how many of these useful pasture-grasses, not available in local woodland
nor in swampy bottoms, were really introduced by man from other lands,
apart from casual distribution from dry grassland of the Chalk or adjacent
tracts.

The chief ecological constituent of the land-area of the district is
maintained in the form of broad stretches of flood-meadow following the
alluvium on either side of the Isis and Cherwell, broadening into the mile-
long stretch of Port Meadow, the Marston Fields along the Cherwell, and
south of the town in Osney and Christ Church Meadows to the Iffley Fields,
over an area of approximately 5 square miles.1

As already indicated, in the earlier historical epoch the original facies of
the country must have been mainly swamp-forest of dense thorn-scrub, with
dominant trees as Ash, Alder, Willow, and intersected by numerous water-
channels carrying a rank vegetation of aquatics and reeds, on clay bottoms
difficult to cross, and full of wild-fowl and wild animals.

The clearing of these alluvial flats by early English settlers, who came to
find cornland and pasturage for cattle on a larger scale, not only gave the
happy solution of the agricultural problem which made life successful in this
region, but also affords the clue to the present existence of the city as a market
town and University centre.2

Whether cleared by fire, or by clear-felling in the approved manner of colonial
pioneers to whom timber is mere ' lumber ', it is evident that the success of the
early farmer depended as much on getting food-supplies for his herds, as corn
for his own family. The alluvial flats, dry in summer and flooded in winter,
affording green pasture all the summer season, as they do at the present time,
even in seasons of greatest drought (1921), also provided abundant hay for use
in winter when the floods were out.

Being too wet to plough, the alluvial flats were thus cleared exactly to the
flood-line for pasture, and tillage for corn followed the rising levels, on higher
clays, bottom terraces of gravel, or the higher outcrops of Corallian soils.

Improved agriculture seeking to ameliorate the damp of winter-flood time,
cleared the streams of weeds, opening up the flow of water for mills, giving
a scheme of clear open streams, abounding in fish, flowing through broad green
meadow-flats, lined with planted willows and poplars, or residual alder and ash
retained for a convenient source of fuel and agricultural timber ; while the tops
of the hills were left as open woodland, predominantly oak, still maintaining
game, and affording food for hogs. There can be no doubt that by early Saxon
times the district was a model of the agriculture of the period, as a flourishing
countryside, peculiarly adapted to the genius of the English race, with wholly
indefinite supplies of clear water, and permanent pasture throughout the
summer, when other parts of the country were dry and burnt up, as on the
adjacent chalk downs.

From the fact that the situation is fairly central for the whole country, with
pasturage and water-supply for an army, exigencies of transport marked the
town which grew up by the ford on the gravel-bank between the confluence
of the Isis and the Cherwell, as an ideal situation for political conferences of the

1 Cf. Plot (i7°5)> p- 52. ' Though Oxford, almost in every part where Industry of the
Husbandman hath anything showed itself, doth produce corn of all sorts plentifully enough, yet it
has much more cause to brag of its Meadows and Abundance of Pastures, wherin as in rivers few
countries may be compared, perhaps none preferr'd.'

2 Plot, loc. cit., p. 20. "Twas the sweetness and commodiousness of the Place that (no
question) first invited the Great and Judicious King Alfred to select it for the Muse's Seat.'

E 2

68 Plant-life of the Oxford District

day; and as accommodation for horses and retainers within the walls was

naturally limited, the broad meadows, especially those south of the town,

afforded an ideal camping ground once the hay was cut.1

Comparatively little change has been effected in the general scheme of

husbandry to the last century. The meadow pastures are still maintained

by the cutting of the hay, a second crop being commonly taken in September,

and the fields more or less grazed in autumn and winter. Flooding has been

much reduced, and in absence of special manuring the hay tends to deteriorate

both in quality and quantity.2 Most of the area has been allotted and enclosed.

Port Meadow is maintained as permanent pasture, and is grazed by numbers

of cattle and horses. Where such pasture-land is not cut, it soon reverts to

Juncus-a.ssocia.tlon (Kennington), or to thorn-scrub (Binsey).

The country beyond the immediate river-area is dotted with farmsteads,
about j mile apart, still maintaining old sites, as indicated by their water-
supply from deep springs ; though many have been swallowed up in the
urban area (Black- Hall) or replaced by institutions.3

Other land maintained as pasture, grazed or cut for hay, or cultivated
under grass and clover or other fodder-plants, follows the normal evolution
of such land, as taken in from the rough common-land or waste.

In mediaeval England pasture-land for grazing and meadow land for hay
were held in common, in addition to the very large amount of open waste land
utilized for rough grazing, and the same system prevailed to the sixteenth
century, or for most of the country to the beginning of the eighteenth. Port
Meadow, originally 440 acres, the property of some 500 Freemen of the City of
Oxford (and not of the ratepayers), persists as a relic of this system, held since
the time of Edward the Confessor ; since, as such flood-land was abundant, it
was hardly worth taking over by the Norman Governor.

It was not until the provision of fields with hedges for cattle ('closes')
came into general use, that other more definite pasture-fields were isolated.
Thus Fitzherbert (Book of Surveying, 1523) recommends the allocation of
pastures of the communal farm-land into a 'Six-field' system; i.e. giving — in
addition to the general Three-field scheme of husbandry of (i) Winter Wheat,
(2) Spring Corn, Barley, (3) Fallow — new fields as (4) Best Leys for feeding
horses, (5) Rough Pasture for cattle and sheep, and (6) Meadow to be cut for
Hay. This would give in practice five fields for winter grazing, and three (fallow,
leys, and pasture) for the summer, with the possibility of alternating the cornland
and the pastures in a rotation.

From this time dates the increasing cultivation of pasture and grass-fields,
still continued and hedged. The introduction of special fodder-plants from the
continent, as Sainfoin, was followed by the general cultivation of ' Dutch ' Clover
(Trifolium repens), and grass-seeds, more particularly 'Ray Grass' (Lolium
perenne). Plot (1705) is particularly enthusiastic on the cultivation of Ray
Grass, and records its introduction to the district by a farmer of Islip.4

1 Plot, loc. cit., p. 21, gives a good list of the early Parliaments and ecclesiastical councils held
at Oxford between 1002 and 1250 (22 in number). It was a comparative accident that Magna
Charta was signed at Runnymede, 30 miles SE. down the river, in a meadow very similar to IrHey
Fields, maintained as mown pasture.

2 Orr (1916), Agriculture in Oxfordshire, p. 180, 'very few of the Thames meadows yielding
anything more than a rather small cut of indifferent hay.' Within living record, Marston Meadows,
treated with abundant stable-manure, harrowed and flooded, yielded record crops of grass ' chin-
high ', probably mainly Dactylis and Arrhenatherum.

3 A typical Oxford farm of 300 acres should maintain 6 families, that of the farmer and
5 labourers, giving an agricultural population of about 60-70 per square mile, as the limit of the
capacity of the land to support. Ashby (1917), Small Holdings in Oxfordshire, p. 177.

The present district taken as about 30 square miles, carries a population, mostly urban, of about
100,000, or 50 times more than the land will account for. This sufficiently indicates the lack of
dependence of the modern population on local plant-life, with consequent indifference to its
problems.

4 Plot (1705), p. 156. ' It having precedence of all other Grasses, in that it takes almost in all
sorts of poor Land, endures the Drought of Summer best, and in Spring is the earliest Grass of any' :

Grassland and Pas tier e 69

The evolution of the pasture-field touches another problem of the country-
side. With the decay of the feudal system, and labour troubles following the
Black Death (1348), a system of enclosure of waste set in, with the formation of
cattle and sheep-runs by larger landowners, as the preponderant feature of
English Agriculture, which became more intensified in the fifteenth and sixteenth
centuries, and has gone on continuously to the detriment of the small holders
for many centuries.1 As the dispossessed peasantry lost the mainstay of their
existence, in the suppression of their 'commoner's rights' to free grazing and
collection of fuel from waste woodland, successive enclosures became a fertile
source of rebellion and rioting, traces of which are found at the present day.2
Pasture represents land set apart for the cultivation of special grasses
(though now including clovers of the agriculturalist), just as woodland is
set apart for the cultivation of a few kinds of tree by the forester. All other
plants come under the designation of * weeds ', some of which may be more
injurious than others (Ranunculus acris, Rhinanthus Crista-galli). The plant-
types of general pasture commonly include some 100 forms, as herbaceous
perennials in closest association, leaving no room for the intrusion of annuals,
or the establishment of the weeds of cultivated land. The grasses number
about 30. There seems at first no special reason why grasses should be
selected as valuable for fodder and hay, more than other herbaceous peren-
nials ; but as a matter of practical experience they are found to be so, as
grasses again make good recovery, and may be even improved by the close-
cropping of grazing animals. A few types of the Leguminosae, more parti-
cularly the clovers (Trifolium sp.), are in practice the only Dicotyledonous
perennials encouraged in the hay-field for their food-value.3

The grasses may be distinguished as: — (i) original inhabitants of the
Woodland (Anthoxanthum odoratum^Festuca elatior) ; (2,) as probably iritru-
sive from dry grassland areas outside the district (Cynosurus cristatus^
Phleum pratense, Festuca ovina, forms) ; or (3) from the Continent by the
earliest immigrants bringing cattle. Under this last heading may be possibly
included many of the finest pasture-grasses which do not occur in competition
with other types beyond the pastures (Festuca pratensis, F. loliacea^Alopecurus
pratensis, Bromtis commutatus]. In more modern times Lolium perenne
owes its wide distribution to its early recognition as the most reliable grass-
crop on any soil ; while the more recent introduction L. italicum is rarely
found far from direct cultivation. Of the origin of the common grasses of

also for 'improving any cold, sour, clay- weeping, ground ' ; and, it may be added, at a maximum
growth on the Sewage Farm.

1 Orr (1922), A Short History of British Agriculture, p. 48.

2 The injustice to the cottager when his grazing-rights and fuel-rights of the common waste land
were cut off, may be gauged by taking the previous estimate of the difficulty of keeping a cow on an
acre of good pasture. Such grazing-rights of keeping a couple of cows and 2 or 3 ponies would be
equivalent to the possession of 10 acres of rough pasture without expense or responsibility, while the
rough wood would supply the year's fuel. To take this from men already living on a narrow margin
as small holders or farm-labourers, implies immediate ruin, which a once-popular estimate of ' three
acres and a cow ' would not go far to alleviate. Hence peasants' rebellions and riots have been the
familiar accompaniment of 'enclosures' to the present time: Otmoor, a wet-waste of 2,000-3,000
acres, was so enclosed (1830), and provided with hedges; rioting took place at St. Giles' Fair.
A relic of ' open ' Brasenose was fenced in 1922.

It is interesting to compare attempts at establishing small holders on the land at the present
time, with little assistance beyond their own holdings which cannot supply everything in the way of
fuel and cattle-feed, and at the same time grow crops. The biology of country-life does not change
very greatly. According to Ashby (1917), Small Holdings in Oxfordshire, p. 177, short of intensive
market-gardening or poultry-fanning, implying the neighbourhood of a large town, there is no
possibility in agriculture of a family existing on less than 30 acres. Yet 30 acres was also the
average holding of villeins under the Norman Manorial system with full Common-rights (Orr
1922, p. 23).

3 Percival (1910), Agricultural Botany, p. 556. Trifolium pratense, T. repens, T. hybridum
T. minus, Lotus corniculatiis, Medicago lupulina ; as fodder-crops Medicago saliva (Lucerne),
Onobrychis sativa (Sainfoin), Trifolium incarnatum, Anthyllis Vulneraria\ hence the relative
abundance of such plants locally is no criterion of their indigenous value.

70 Plant-life of the Oxford District

the Hay-crop little is known, and in absence of definite information it is
usual to assume that they are at any rate * indigenous ' to the country. On
the other hand, as a hay-field with a densely-mingled crop of half a dozen
or more of grasses, all flowering at the same time, is a biological absurdity
from the standpoint of cross-pollination by the wind, this special community
of many forms sufficiently indicates the complex origin of the association
and its artificial selection.

The Hay-crop follows a distinct succession, and the grass begins to grow
in March ; the undergrowth becoming thick and the shoots elongating in the
early weeks of April, to a foot high at the beginning of May. The species
flower out in succession, beginning with Anthoxanthum? to be followed by
first Bromus mollis, Alopecurus pratensis, and Poa pratensis. The last is
dominant in the early weeks of May, with addition of Festuca duriuscula,
AvenapratensiS) Poa trivialis? The main crop comes on with the flowering
of the taller grasses Dactylis glomerata^Festucapratensis^\\^ Arrhenatherum
avenaceum. The closing up of the fruiting panicles of this last form is the
sign that the crop is ready. At this time Anthoxanthum and Bromus mollis
may have shed their seeds, and be wholly dried out.3 In fields which are not
cut at this stage other grasses come on, particularly Trisetum flavescens^
Cynosiirus cristatus, and the grasses of early July, as Agrostis alba, stolonifera^
and Phleum pratense. Lolitim perenne flowers on from the end of May to
July with greatest range ; the finest grasses of the Hay-crop, Alopecurtis^
Festuca pratensis^ have the most restricted period, as they have little distribu-
tion beyond the pastures. With the cutting of the Hay-fields flowering
grasses greatly diminish : a few flower sporadically into the autumn, but
these wholly die down by mid-November, leaving the fields bare, though
more or less green, over the winter months. The second crop of the water-
meadows is usually small in quantity and poor in quality; it commonly
contains no flowering grasses and few flowering herbaceous perennials.
Fruiting Leontodon autumnale is characteristic, in quantity sufficient to tint
the field. Only in the extreme case of late spring floods can it compare
with the main crop.

From these considerations it will be seen that the grasses of pasture-land
normally present a working-period of just 3 months in the year, from
mid- March to mid-June, as compared with the 6-months period of the
trees of deciduous woodland. Such attainment of quicker returns, which
affords the clue to their high degree of specialization as reproductive
mechanisms, extends to the herbaceous types associated with them, in a
manner which recalls the association of the herbaceous flora of the woodland
with the trees of high-forest, regarded in turn as the main crop; the
ecological interests of the agriculturalist being much on a par with those of
the forester.

Pasture-land may be put up for hay during the growing season, and
grazed during the rest of the year, or a hay-crop may be taken one year
out of two (or more, on poor ground), and grazed the others. Port Meadow
has not been cut in living memory. Grazing cattle return a certain amount

1 First-flowering record ranging from April 22, in early seasons, to May 8 in late. Alopecurus
pratensis, a more typical grass of the early Hay-crop ranging from May i to May 17.

2 Fields are closed for Hay about the middle of May, as the crop becomes too thick to walk
over without damaging it. Fields trampled over by footballers in the winter may be at this time
gardens of flowers.

3 In the early dry season of 1921, hay-cutting began June 6, and the crop was carried as cut.
The water-meadows (Iffley to Sandford) were carried by June 21, and the second crop was saved by
Sept. II. In the delayed rainy hay-harvest of 1922, cutting was general only in mid-July, though
the first alluvial field was cut June 12. Later alluvial fields were cut at the end of July and the last
Iffley Field (and poorest, below the lock) on August 5, 15, 25, and not all carried until Sept. 5.
On other fields a second crop was taken in the first week of October.

Grassland and Pasture 71

as manure ; the mass of material consumed by a few horses or bullocks
may be estimated by comparing adjacent pastures, one growing a dense crop,
the other, with only a few head of cattle, kept wholly bare, with no flowers
except a few residual Buttercups.1 Where grass has been cut for hay through
centuries of agriculture, it is obvious that the continual drain of combined
nitrogen, and especially phosphoric acid, may soon become a critical factor
for plant-life, rendering manuring essential. For this purpose superphosphate
and basic slag are recommended.2

The management of Clover-leys, and crops of fodder-plants, as Sainfoin,
pure or mixed with special grasses (Lolium perenne, L. italicum) or Clovers
(Trifolium pratense, T. repens, T. minus), follows the same periodicity as
that of permanent grassland with its weeds, differing only in the dominance
of one or two selected types, and increased possibilities of manuring as these
follow in the cultural rotation, and hence becomes the more artificial and
' assisted ' by human agency.3

It must be noted that from the standpoint of the agriculturalist, the
tending and utilization of pasture-land is really the problem of growing a crop
of the best feeding-grasses, to which all inferior grasses as well as all herbaceous
plants (with the exception of the Clover-class already mentioned) are objec-
tionable weeds. About half the species of grass commonly found in Hay-
fields are entirely worthless as fodder, and merely occupy the ground which
should be available for better forms, apart from the general presence of
Carices and Juncus in low-lying ground. Such weed-grasses include common
forms as Anthoxanthum odoratum, Agrostis alba, Holcus lanatus, Air a caes-
pitosa, Avena pratensis, Bromus mollis, Hordeum pratense, Briza media,
apart from the intrusives of waste ground and ditches.4

In this respect the story of the evolution of pasture runs very parallel
with that of the problems of forestry. As the pasture of the past has tended
to making the best of a scratch lot of indigenous plants, some better than
others, and hence encouraged in a mixed culture ; so the future remains with
the definite sowing and careful cultivation of either a few types of different
succession and degrees of maturation for grazing purposes, with a time-limit,
or the production of a pure crop of one form for a definite commercial
purpose.5 It is this mingling of the older custom with the new agricultural
methods, as in the supersession of ancient forestry routine by more modern
continental practice, which renders the present epoch of plant-life in the
district so interesting, as being in an eminently transitional phase ; though
while the degree of success attained by the older methods is known, that of
the newer departures still remains highly problematical.

Among the great range of Herbaceous perennials associated with the
Hay-crop may be distinguished : —

(1) Those flowering out in early summer before the grass begins to grow

(Daisy, Dandelion, Ranunculus bidbosus, Luzula campestris).

(2) Plants growing up with the grass-crop, with elongated inflorescence-

axis keeping pace with the grass (Plantago lanceolata, Ranunculus

1 The return of excrement by cattle is enormous, though it only represents a portion of the
material taken from the land. In the dry summer of 1921, with no rain from February to September,
all droppings dried on the fields, and there was practically no decay. In many parts (especially
Port Meadow) the ground was distinctly blackened, and there was more dung than grass. At
present Port Meadow affords grazing for about 300 head of cattle and horses, also 100 or so geese.

2 Cf. Orr (1916), Agriculture in Oxfordshire, for notes on the use of superphosphate and nitrate,
p. 213.

Memoranda of Field and other Experiments, Rothamsted (1900), p. 22, Permanent Grass Land.

3 Percival (1910), Agricultural Botany, p. 558. Grass and Clover Leys of 1-3 years duration.

4 Percival, loc. cit., p. 530.

Armstrong (1917), British Grasses and their Employment in Agriculture, p. 51.

5 Percival (1910), p. 565. Mixtures for Permanent Pasture.

72 Plant-life of the Oxford District

acris, Chrysanthemum Lezicanthemum, Rumex acetosa, Crepis tar ax-
acifolia).

(3) More xerophytic types, flowering after the hay-harvest, in the dry
summer when the grass is perennating {Centaur ea nigra> Knautia
arvensis, Achillaea Millefolium^ Leontodon autumnale}.
A few types will flower in the damp aftermath-period of September,
but the fields are characteristically floriferous only in May and June.1

The character of the weed-flora also varies with the nature of the soil
and the water-content : —

(1) Damper alluvial pastures with great range of type, and clay pastures

above the flood-level, produce spring-flowering Cowslip, Orchis Morio,
Saxifraga granulata, Cardamine pratensis ; later with the Hay-grasses
Ajuga reptans, Lychnis Flos-cucidi, Rhinanthus Crista-galli ; and in
summer Silaus pratensis, Scabiosa sttccisa, Sanguisorba officinalis ;
together with grasses of subaquatic habit \-Glyceria fltdtans, Poa
trivialis, several forms of Carex (io),as C.glauca, C. rip aria, C. hirta,
and Juncus-forms increasingly abundant on more waterlogged soils
(J.glauczis).

(2) On high pastures with sandy soils, more particularly of the Corallian

series, a drier xerophytic flora predominates, grading to hill-pastures
which afford no appreciable crop of hay; characteristic forms are
Carduus nutans, C. eriophorus, C. acaulis, Ononis spinosa^ and on
exposed areas Helianthemum vulgare, Lotus cornictdatus, and Echium
vidgare.

(3) Of the larger perennial forms only kept down by rigorous mowing,

the more striking are Heracleum Sphondylium, Angelica sylvestris,
Spiraea Ulmaria, Carduus arvensis, C.lanceolatus, and often C.palus-
tris and intrusive Equiseta.

(4) As an interesting special case may be included ' Goose Pasture ', as

seen at Medley, Binsey, and Port Meadow ; characterized by a fine

turf, close-cropped, highly manured, with abundant miniature forms

of subaquatic habit, I inch or so high, and flowering at this size

(Myosotis palustris. Stum angustifoliuni,Hippuris> Veronica Anagallis,

Apium nodiflorum> Ranunculus Flammula, Potentilla anserina.

It is so far evident that the biology of the pastures presents a wide field

for systematic ecological study, as each area requires to be taken on its own

merits ; the possibilities of climatic, edaphic, and cultural conditions are

so varied, and the last liable to change in successive years. In past time,

for centuries, the greater part of the hay-producing area has been left largely

to the chances of nature, with little return, except from flood-water and the

dung of grazing cattle, and mown at midsummer by manual labour. Owing

to the slow rate of mowing by scythe, and the risk of bad weather when the

crop is lying on the ground, the older expression of ' saving ' the hay, thus

obtained from natural causes, becomes significant. The time for cutting

followed the exigencies of labour, and implied further risk. A man with

a modern reaper and pair-horse team can cut 10 acres in a short day's work,

as compared with the older style of scythe-work, in which good men

averaged an acre per day.2

" ! The damper levels give the greatest floral display. Fields on clay and alluvium give stretches
golden-yellow in May, with Ranunculus acris ; sandy and gravel pastures are later white with
Chrysanthemum Leucanthemum. The floral display commonly diminishes with the growth and
dominance of the taller grasses, and such fields may show dull-red with fruiting Rumex acetosa.
The finest floral effect has been noted in water-meadows of which the cutting has been delayed by
rain until late July (Oxey Mead), when Spiraea Ulmaria and Sanguisorba officinalis become pre-
ponderant.

2 Mowing was done by piece-work, the men working in gangs, with scythe ; a 6 ft. man cutting
a 6 ft. swathe. A good man is recorded, within living memory, as working from 4 a.m. to 9 p.m.,

Grassland and Pasture 73

The best hay-fields at the present time are those of the broad stretches
of alluvium on the banks of the Cherwell (Marston district), and other
uncontrolled streams (Hinksey Stream, Cold Arbour). Where the main
river is locked and kept at head-water, full water-content maintained above
the lock affords a good crop (Oxey Mead, Tow-path fields, and Meadow Lane
above Iffley Lock) ; but a reduced supply below the lock, with low tail-water,
implies a scanty yield. The luxuriance of the floral display and variety
follows that of the grasses.

Roadsides.

To the ordinary pedestrian the open roadside plays a part out of all
proportion to its intrinsic value botanically and the amount of ground
involved, since roads afford the primary means of exploring the countryside,
and roadside plants if large enough compel the attention of the passer-by,
and even of the motorist. Although suggestively viatical? such plants do
not constitute any special ecological class. It is evident that all roads are not
only wholly artificial, but of comparatively recent formation, as also liable to
rapid modern improvements. Any plants colonizing the sides must be at
best residual strays, or immigrants from fields, woodland, and waste places ;
that is to say, all are plants of other stations, finding a locus in these new
tracts, and surviving as best they can. It is also obvious that a road open
to any considerable traffic offers minor areas of local denudation, as broken
ground, in which strays from other stations are again so far humanly
assisted in their struggle to acquire some tenure in unoccupied ground.

Where only the merest relics of waste or common land remain, and the
fields, pastures, and woodland are increasingly closed to the general public,
the foot-paths, way-sides, and public roads remain the station to which the
botanical student is increasingly relegated. Hence it is preferable to regard
the road-side with its boundary fences as a convenient station for meeting
the residual types of other formations, now maintaining a precarious exist-
ence, under wholly artificial conditions, and open at any time to ruthless
destruction at the hand of any local Road-Surveyor.2

The possibilities of the situation are considerable, ranging from a
modern urban road with no vegetation whatever, to a primitive country
wayside, neglected and derelict, which however economically inefficient as a
means of transport, may, in the course of 50-100 years, become a thing of
beauty, as one of the most picturesque features of the countryside. Such
neglected roadways exhibit : (i) a general regression to grassland, (2) the
introduction of thorn-scrub,3 (3) passing on to all stages of regressive wood-
land, (4) affording ultimately an avenue of trees of high-forest, meeting
overhead in full canopy, and sheltering a wealth of woodland forms in a
humus-bottom.

In mediaeval England, as there were no hedges to the fields, so there were

no roads as now considered. Main roads had been constructed by the Romans

for military transport, and the partial remains of a Vicinal Roman Road below

Shbtover, are still sufficiently well-defined to mark the track, though this has

been lost in places by ploughing (Stow Wood, Baldon).

In Saxon, Danish, and Norman times, the river was the main line of

communication, and local roads were mere cattle-tracks from one township to

consuming in the time a quartern loaf of bread and a gallon of beer, with possibly a dozen pipes of
tobacco.

1 Watson (1847), Cybele Britannica, p. 66, includes 'viatical' with plants of rubbish-heaps and
frequented places.

2 Highway Surveyors (1835) can call on the owners of any hedges adjacent to roads to have
them ' cut, pruned, and plashed ', and the trees lopped and pruned, from October to March.

3 ' The wayside where thorns grow up ', as a general phase of inefficient husbandry.

74 Plant-life of the Oxford District

another, foot-paths between adjacent farms and cottages, or bridle-paths through
the woodland. The latter leave no trace ; though several roads around Oxford
suggestively link older cottage-sites, as they follow the course of the same
subterranean stream supplying the wells.1

Cattle-tracks, broadened 30-40 ft., and trampled by the passage of herds
and rounded flocks of sheep, mark the main routes to local markets, as indicated
by the ford which gives its name to the town. Probably the first foot-tracks
followed the sides of the streams, as fisherman's paths of to-day, and along the
margin of the winter-flood, thus linking up the flood-line villages, and following
on to the gravel-patches available for crossing.2

Old roads across country were grassy rides in the waste and woodland,
in which, as in the case of pasture-land, the regeneration of trees was pre-
vented, bramble and bracken cut out, as in the present rides through woodland
(Bagley). These were not separated from the open country by hedges. In
swampy levels attempts at a firm bottom were made by putting down rough
wood-faggots (the beginning of a ' corduroy ' road) ; or in worse spots by
loads of rough rag-stone, as dug or quarried. As this material sank in the
mire, more was added, as in the construction of more modern lines of road
without special foundation. Deep ruts were neatly filled with rag-rubble.
Similar roads in all stages of evolution persist to the present day as farm-
tracks: many local farms still have no other approach, and are far from
any main road.3 Such farm-roads in the present amenities of the countryside
are increasingly labelled ' private '. The width of these older ways was
established when hedges became general in the seventeenth century, at a
generous range of 30-40 ft. Main roads with greater traffic are 50-60 ft.,
and the thorn hedges in more modern times may be continued in the actual
fence of houses and gardens along the route. Local encroachments on such
roads, by ingeniously removing one fence and cultivating up to the other,
reduce such ways to field cart-tracks, or foot-paths with a general right-of-way.
In such case, a quite reasonable notice to avoid standing crops soon becomes
a warning to all « trespassers '. A ' foot-path ' should be wide enough for two
men to pass when both loaded with tools or produce, without being obliged
to stop and put things down ; such paths may be fenced to 6-8 ft. ; a 4-foot
way is a nuisance.

At a later date minor commercial transport was effected by pack-horses.
All heavy traffic came up the river by barge from Henley, to the early nineteenth
century, and the river was improved for navigation, and locked to Oxford (1635)
long before roads were taken in hand seriously.* Clay was the terror of all
older roads, and in clay-areas deep ruts would be cut by heavy traffic, as in
shifting timber-trees.5 Pack-horse tracks rise in a straight line, over the gravels
and sands of the nearest hills, to their destination ; as over Shotover on the
London Road, over Wytham Hill to Eynsham, and straight up Ferry Hinksey

1 Kennington Lane, Road from Littlemore to Garsington, Boar's Hill.

2 Remains of such paths are seen in the present road from Wytham to Botley, and thence to
Ferry Hinksey, continued as a foot-path to S. Hinksey, and then again to Kennington Lane.
Remains of a similar flood-path on the Iffley side are seen in Meadow Lane, now cut off by Playing
Fields from the approach to Magdalen Bridge.

3 Sescut, Chilswell, Minchery, Blackbird Leys Farms. The present state of the ' Roman Road'
and especially the diverticulum to Brasenose Farm, admirably illustrate these older grassy roads, now
confined within hedges. These require to be seen in wet winter weather. ' Mud Lane ', Cowley, is
a suggestive relic ; now a back-way continued as an old foot-path over the Golf-course. The
' Plain ' of Shotover remains as a part of the Old London Route, broadened at the top to 75 yds., as
if for grazing purposes or camping. Excellent relics of such ways are seen in ' Copse Lane ' and
1 Marsh Lane ', Marston, as sections of an older road to Elsfield. A neglected section of ' Copse
Lane ' under trees, in wet weather, still affords a vivid idea of Oxford clay mire as trodden by cattle.

4 The River-road is interesting because it implies a tow-path and a right of way along one side
of the river at least ; opening this region up to the observer as it passes through pasture-fields of the
alluvium, not otherwise readily accessible ; though arable fields are more usually separated from the
track by a hedge : cf. Meadows of Yarnton, Oxey Mead, Wytham, Binsey fields, Medley fields,
Iffley Fields.

6 A clean-cut rut in Bagley Wood (1922) on Kimeridge clay was 12 in. deep in the groove of
older ruts, or 16-18 inches below the level of the centre of the track.

Roadsides 75

Hill to Besselsleigh for Faringdon and the^est, with gradients ranging i in 20
and i in 15. Such hill-tracks leave little trace, except as a foot-path still in
use, and marked on the Ordnance Map. In some cases the surface-stream
culverts are still covered by large blocks of stone, showing former care in their
maintenance.1

All such old tracts revert to grassland when not used; with further
regression to thorn-scrub, and regressive woodland on the sides, or where
wholly neglected; thus carrying a general woodland flora,2 and deteriorating
again to the waste from which they were originally isolated.

As opposed to these local and older tracks, main roads came in with the
increase of transport and the demands of wheeled traffic in the seventeenth and
eighteenth centuries. With no pretence at road-making, it took 2 days to get
to London (50 miles); and a fast coach to do it (D.V.) in one day was put on
as a novel departure in 1667. 'Turnpike' Acts (1662-1763) gave local
authorities power to collect tolls towards the upkeep, and improvements began
in the main roads. By utilizing local sands and gravels, the clay-problem was
largely solved, and fairly good gravelled primary roads, between the larger
towns, were in existence at the beginning of the nineteenth century. But little
could be done until the construction of a properly metalled road had been
taught by Telford and Macadam. The former advocated a pitched stone
foundation in the French (Roman) method ; the latter thorough draining and
an impervious surface. A combination of these methods is preferable on a clay
bottom.3 Gradients were also reduced, with an approximation to i in 30
for horse-traffic, and new roads were cut; e.g. Headington Hill cut down,
with a route avoiding Shotover for a new London Road ; the Eynsham Road
passing south of Wytham Hill, and the West Road to Besselsleigh passing north
of Cumnor Hurst. Hinksey Hill, which appears to be unavoidable (maximum
gradient i in 10), is not a primary route. At the same time it may be noted
that a steep road down-hill to a market-town is less disturbing to market carts
going home empty, than may at first appear. The ' Botley Causeway ', crossing
6-7 streams by 7 bridges (Seven Bridges Road), had been made in i77J>
as a new entrance to the town (avoiding Ferry Hinksey), and the ' New
Road '(1766).

These roads followed the general dimensions allotted to older cattle-tracks,
and were metalled down the centre for a width of 16 ft. or a width sufficient to
let two vehicles pass, or only 24 ft. in a 60 ft. road, leaving grassy residual
tracts on either side of 6-7 to 10-12 ft. in 30-40 ft. ways.4 These side spaces
are maintained as beneficial from the standpoint of admitting sun and air to
the road-surface, as also affording space for a drainage ditch, channels and
outlets, as well as convenient dumping-ground for road-scrapings and mending-
material. Only in the immediate vicinity of towns are they further developed
as foot-paths. In more important roads such tracts tend to disappear, as more
accommodation is wanted for wheeled traffic, and tar-macadam is now taken
up to the hedge-line. In the more general case, these grassy sides, blocked
by heaps of material, or cut by cross channels, are of little use for foot-
passengers, and they are allowed to revert to grass or anything that will
cover their unsightliness. With complete neglect, they pass through all the

1 Cf. the Besselsleigh path between Hen Wood and Cumnor Hurst, and the 'Ridings' from
Headington to Horspalh.

2 « Copse Lane ', Marston ; ' The Ridings ', Open Brasenose ; « Blackberry Lane ' section of the
Roman Road.

3 Cf. new loop road at Iffley Turn (1922).

4 Such roadside wastes along public roads also express the last relics of ' common land', from
which cottagers collect dead sticks, cut fodder, or pasture cattle (under supervision) as they are the
last resort of the wandering botanist and gipsy. Ancient common grazing land and open waste
presupposed cattle-herds. With increasing traffic, and public roads passing over commons, further
attention was required to prevent accidents and straying.

Interesting survivals of the ancient profession of « minder ', usually relegated to a small boy,
cripple, or the oldest inhabitant, may be still encouraged at Binsey, Medley, and Godstow, at tow-
path gates.

76 Plant-life of the Oxford District

stages of rough herbage and regressive scrub to tracts of small flowering-trees
which may give a pleasant appearance ; more commonly they are allowed to
remain as simple waste, harbouring all the weeds of cultivation and the hedge-
row, a mass of coarse grasses and larger herbaceous forms (Heracleum,
Pastinaca, Carduus crispus, Anthriscus, Torilis). Where the entire agricultural
country may appear as a garden, with beautifully clean arable fields under corn
and roots — the hedges maintained trimmed to the level of the standing crops,
as the regulation plashed thorn-fence — such roadside wastes present a striking
contrast, as the last remains of the indigenous flora, which seem strangely out
of place in a civilized country.

Roads are again undergoing a system of reconstruction, and tar-macadam
solves the problem of dust in summer, as well as of mud in winter.1 The
dusty roadside was a feature of the nineteenth century, and a relic from the
pre-railway coaching days. Motor-traffic soon requires a road broader even than
the old-time cattle-track : an optimum width for main lines of 700 ft. has been
suggested (France), 120 ft. in the London area.

The Railway-line dates from 1844 (from Didcot) ; both the G.W.R. and
the L. & N.W.R. follow the alluvial flats north and south from Wolvercote, and
the former to Sandford and Radley, on a low embankment of ballast-gravel and
clinkers. This presents little botanical interest ; the banks being gay in early
summer with Senecio squalidus, Chrysanthemum Leucanthemum, Lotus corniculatus,
later with Linaria vulgaris, but apt to run dry in hot summer. The Wycombe
Line through Thame runs on a higher embankment to cross the Thames below
Iffley ; it cuts through the Corallian rocks and Calcareous Grit before Littlemore,
and by a deep cutting and tunnel through the Portland beds and Shotover sands
at Horspath. These embankments and cuttings exposing calcareous rocks
carry a varied and abundant flora.2

The main line down the alluvium, with several bridges over minor streams,
cuts the older flood-level into two tracts. That on the west is subject to floods
from the uncontrolled Hinksey Stream,3 and the railway constitutes an effective
barrier to the exploration of the area.

It may be noted that botanical interest centres in the fact that roads are
of very modern organization, and have little relation to the indigenous
flora. Where the track goes through woodland, it will show along its sides
all the characters of regressive woodland ; if through arable fields or pastures,
it will carry all the weeds of these formations, the more as it is less cared-
for. As traffic implies denuded ground, ' assisted ' vegetation will find a
station ; hence ' viatical ' plants are merely assisted indigenous forms,
mingled with assisted aliens — whether brought by wind, or on the feet of
men and horses, the mud of cart-wheels, and the hair of animals. The dusty
roads of the nineteenth century, with exposure to sun and wind, favoured
desiccation, which implies a preponderance of xerophytes in dry summer.
Droppings of horses and cattle, adding manure to denuded areas, encouraged
the common weeds of waste places and human refuse, as also salt-storing
weeds and aliens. Modern usage of tarred roads and rubber tyres tends to
eliminate all plants whatsoever. It is interesting to note that in a modern
transitional phase, the Oxford district supplies admirable examples of modern
road, as also of all the older types that have been.

1 Cumnor Hill was a mire in 1921 : Hinksey Hill was formerly so dusty in hot summer that one
could ride up it and not see others going down.

2 A slight sample of a regressive railway embankment, following disuse, is seen near Wolvercote
(Peartree Farm). The embankment approaches to the bridge over the river below Iffley were
reconstructed 1922.

3 The Railway line was washed out in 1894, following which the line was raised somewhat, and
a series of 20 culverts made in the embankment to let the water through (Kennington Lane).

77
Crops and Weeds of Arable Land.

A special type of plant-formation, associated with land under tillage
by plough, gives the case of the secondary vegetation associated with agri-
cultural crops. The main crops locally are confined to fields of Wheat,
Barley, Oats, Beans and Peas, Turnips and Swedes, Mangel and Potatoes.
No other crop of importance is in present cultivation. Sainfoin, Vetches,
Clover and Rye, as fodder crops, follow the type of Hay Pastures. Crops
of minor importance are grown, as Cabbage and Lucerne. Wheat is still
the most important crop, though potatoes are increasing.1

The denizens of arable land come under two distinct headings of (i) the
crop, as the plant intentionally cultivated, (2) the 'weeds', as intrusive vege-
tation, of more or less objectionable character from the standpoint of the
cultivator, as the accidentia of the process. The ecology of the main crop
is the business of the agriculturalist ; a special study involving the relation of
that particular plant in mass-cultivation to its climatic and edaphic condi-
tions ; as also its relation to preceding crops in the cultural rotation, and the
isolation and breeding of improved ' varieties '. The plants thus cultivated
may be definitely aliens of a warmer climate (Wheat, Barley, Oats, Rye),
or again the specialized representatives of types more or less indigenous
(Turnip, Brassica Rapa ; Beet, Beta maritima) ; the former cereals with a
seasonal periodicity of their own, the latter root-crops of biennials vegetat-
ing in the first summer.

Subsidiary forms, associated with the main crop, draining the soil of
food- supplies and water, are distinguished as * weeds ' ; the object of the
cultivator being to eliminate them as far as possible, giving clean ground
for the main crop and making the utmost of the ecological conditions of
soil and climate.

As all such arable land has at some time been taken into cultivation
from cleared woodland or open pasture, the indigenous vegetation may
persist to a certain extent ; while intrusion from similar pastures, from
adjacent woodland, and from residual or regressive flora of hedges, may
continually add to the source of weeds. In addition to this, alien seeds are
being continually introduced with the seeds of special crops, and other weeds
may be introduced from roads and waste places on the feet of men or horses
in the process of cultivation. The supply of weed-vegetation is thus continuous,
and follows the exigencies of the agricultural situation. With the elimina-
tion of hedges, cultivation of fields as wider tracts of land, complete elimination
of all residual indigenous flora, and the preparation of clean seed, the weed-
problem is reduced to a minimum.2

The special features of such field-crops afford a study of plant-life on a
large and most intensive scale, as a pure association of individuals, in which
no other organism is considered.3 All have been considerably modified from
their ancestral forms, and are so far ' domesticated ' that they do not again
'run wild' or re-establish themselves in competition with the indigenous flora.

The most obvious character of arable land is the small number of plant-
forms in cultivation. As in all human efforts at domesticating animals and
plants, the tendency is to exploit isolated forms with special characteristics
at the expense of the rest of creation ; and thus the cult of the horse,

1 Orr (1916), Agriculture in Oxfordshire, p. 195, with maps and county statistics from 1866-

Plot (1705), p. 157, records Carthaimts sativus, Safflovver, cultivated for scarlet dye at Aston,
and Caraway at Bampton.

2 Brenchley (1920), Weeds of Farmland, p. 43.

3 Percival (1910), Agricultural Botany, p. 571. 'A very large number of native wild plants,
which, although in Nature's great collection of living things no doubt perform some useful work, are
nevertheless from the farmer's special point of view, practically without any appreciable value.'

78 Plant-life of the Oxford District

bullock, sheep, and pig, runs parallel with that of wheat, beans, turnips and
mangel. The ideal of the cultivator is to get one paying crop per season of
one variety of one plant ; since every additional type adds enormously to the
biological complex of the farm, requiring special methods for dealing with it,
and increases the intellectual pressure on the cultivator. It is owing to this
very fact that the ecology of the agricultural crop becomes wearisome to
the outsider ; and in walking through a field of corn or mangel, one is
inevitably attracted by the intrusive weeds rather than by the crop ; because
the former by contrast afford the greater variety, may possess a certain
aesthetic value, and are admittedly on their own.

On the other hand, it must be remembered that crops are grown as
food for the human race or for cattle, — that there is no other way of getting
food to keep the race going, and that advancing civilization has been based
on the efficiency of its food-material.

The first cereal food of the human race was undoubtedly the grass Oryza
(Rice), easily puddled in a tropical swamp with no agricultural implements, and
giving a crop in the dry season of hard grain, capable of indefinite storage and
transport with little damage, to be readily converted into good food by the use
of a little boiling water.

These factors imply a human society living in a tropical climate with
marked wet and dry seasons, as also a knowledge of fire and pottery. From
a race of arboreal fruit-eating organism, human beings thus became j^^-eating ;
the greater efficiency following the utilization of the food-reserves of the plant-
embryo itself, rather than the mere excess deposited in the fruit-wall and
devoted to purposes of ' animal-dispersal '.

From such swamps, characteristic more particularly of the alluvial flats of
large continental rivers of the old world land-mass, similar civilizations followed
around the coast-line, as migrants in dug-out canoes seeking estuaries of other
rivers, and so founding the civilizations of the older world. A western Sumerian
migration, probably from the Indus-delta, colonized the delta of the Euphrates,
and being isolated by deserts, further advance took in the grasses of the sandy
hinterland, also capable of being cultivated by the rudest plough as a sharpened
stake. From such grasses, Wheat and Barley have more particularly developed
as the main food-supply of Western Europe, as civilization spread to Egypt and
along the shores of the Eastern Mediterranean to Greece and Rome, and from
Tyre to Carthage, to become the dominant food-grains of the dominant races
of the present world; as the food-value of the Wheat-grain gives greater
efficiency than that of Rice.

The English, in turn, came as immigrants to Great Britain seeking corn-
land, and the parts of the country too hilly or too stony for the ready cultivation
of Wheat, remain to the present day as the * Celtic Fringe '. The colonization of
the prairie lands of Canada in the nineteenth century follows the same succession.
The cultivation of the Wheat-plant is not only the essential basis of
modern Western civilization, but it is the foundation of all English agricul-
tural practice. Wheat is still the key-crop of arable land, as arable land
implies cultivation by the plough, and the plough was invented for the tillage
of Wheat in sandy soil, though now specialized for plants grown in stiff clay.
Wheat, Triticum sativum^ comprises many much-modified mutants and
hybrids to the number of several hundred,1 of a short-season xerophytic and
highly specialized grass of the Assyrian hinterland, in cultivation for probably
many thousands of years. The prototype, if not actually the Triticum Hermonis
of Aaronsohn, still growing wild in Palestine, would be so far similar that the
latter may be taken as affording the clue to its special biology, as a plant of
sub-desert environment and dispersal. That is to say, it requires a dry hot
season for seed-maturation, but sufficient water-supply in the soil during the
vegetative growing period.

1 Percival, loc. cit., p. 518.

Crops and Weeds of Arable Land 79

The plant is a typical mediocre grass-form, tillering in field-cultivation to 3-5
culms, with a maximum of 60-100 when single plants are grown isolated under
special conditions, as on a manure-heap. The inflorescences are compound
condensed spicate systems; the spikelets, with several flowers, setting 2-4 seeds
each. In the original state the spikelets bore long awns in the manner of
Barley (Bearded Wheat), and the main rachis broke up into separate segments
for dispersal by the wind (Emmer). Vestigial awns commonly occur on
' Beardless Wheats ', and the grain lies loose in the pales and is readily threshed
out ' naked '. The seed is sown in early autumn (September), to take advantage
of warm rains,1 on land ploughed generally following Beans or Clover, in drills
6 in. apart. The seedlings come up in 2-3 weeks; and by the end of
November the fields are covered with a green mantle, 6 in. high. Little growth
takes place over the winter, until March ; the crop increasing in density during
April and May. The tillering shoots send up culms increasing by telescopic
extension of the internodes from below, to 3 ft. in mid-June. The plants flower
at Midsummer (4-5 ft.) and the crop is matured early in August.2

As a short-season grass of a warm Mediterranean climate,8 the wheat is still
autumn-sown ; but in a northern summer the vegetating period is extended by
2 months, and the plant is so far an exotic beyond its normal dispersal range,
now maintained wholly artificially by man, and not running wild. Seedlings in
unoccupied ground, as waste-heaps, may grow more or less successfully a second
season, but rarely come up a third. As in the case of the American Zea Mat's,
the mechanism of auto-dispersal has been completely eliminated in cultivation.

The periodicity involves an autumn germinating season, and a summer
growth continued a month longer than the hay-crop of indigenous grasses.
Weeds germinate and grow up with the crop in a close association which cannot
be weeded readily except by hand and in early stages.

Western civilization is based on the production of food-grains of which
Wheat is predominant as alone giving good ' bread ', together with Barley as an
inferior corn, no longer employed for bread, but essential for brewing beer.
The condition of English Agriculture has followed the evolution of methods
for dealing with such cereals, and any consideration of the weed-accidentia of
the crop requires some historical presentation of the special problems of its
cultivation.

Fallow. The ancient barbaric custom of growing corn to the exhaustion
of the soil and then moving on, implies a more or less nomadic habit and
abundance of free land. More settled civilizations of the Eastern Mediterranean,
with clearer ideas of property ownership, introduced the practice of fallowing,
with the object of giving the land a rest (cf. the 7th Sabbatical year in
Palestine). In Greek and Roman cultivation a general practice (Virgil) let the
land lie fallow, and grow a crop in alternate years. This solved the problem
of Fungus-diseases (Rust, Pucdnia ; Smut, Tilletia ; Claviceps, etc.) which
inevitably follow a pure successional crop grown on a large scale ; as the
perennating fungus-spores normally germinate in the succeeding spring, but
do not last another year. The herbaceous weeds were probably taken as
granted. The common weeds of corn-land to-day are but the same as those of
the fields of Carthage and N. Africa which supplied the corn of the later
Roman Empire.

As a matter of fact, the exhaustion of the land was due to the great growth
of weeds in successive years, and the land becoming 'foul' required to be
cleaned. In a field left derelict the alien weeds of cultivation would, in the
course of time, go down before the indigenous flora, more particularly the

1 Orr (1916), p. 197. Cf. older custom of beginning at the end of July. In the early season of
1921 fields were steam-ploughed for wheat after beans, in the first week of August.

2 In the dry summer of 1921, wheat was harvested before the end of July.

3 In Palestine wheat was sown at the onset of the rainy season at the end of October, and grew
throughout the mild wet winter, to be harvested in April or early May, as a 6-month crop. Barley,
sown in February, less water-demanding, with surface-roots, as a short-season cereal, is also harvested
in May, in 3 months. In Alaska, with ' midnight sun ', wheat is harvested in 90 days from sowing.

8o Plant-life of the Oxford District

commoner grasses ; but a better plan would be to plough the fallow repeatedly
to kill successive crops of germinating weed-seeds. The poverty of the crop in
this part of the world, as also the general method of fallowing, is indicated by
Walter of Henley for the early thirteenth century. Two bushels of grain were
used to sow an acre, and 6 bushels is recorded as a satisfactory crop. This
probably indicates that less than 6 bushels, e.g. 4 per acre, as only doubling the
seed-output, would be the limit before fallowing. The general average yield per
acre for England at this time appears to have been 9-10 bushels.1

In Saxon times the arable land of a township was held in common, as
unfenced * field', and only enclosed while the crops were standing. After
harvest the hurdles were removed, and the field left open for grazing.
Cultivation by plough with yoked teams of oxen 2 implied difficulty in turning,
and fields were cultivated in ' strips ' of an acre or so. In order that the land
of the community might be shared equally, the holders had strips in different
parts of the ' field ', in the manner of scattered allotments. The acre> expressing
the amount of land ploughed by an ox-team in one day, became the unit of
land-area, and might vary in different countries; an English acre is half as
much again as the Roman. The standard English acre was established as
10 chains long (220 yards = a furlong furrow), and one chain (22 yards =
4 ' poles ', 'land-yards', or i6| ft. spears) wide.

The same method of strip-cultivation was practised in Norman Manors,3
and was only eliminated with the decay of the Feudal system. The aggregation of
the holdings of the villeins as small holders into associated lots, and the secondary
addition of permanent hedges made the more modern farm. The fallow field was
ploughed in April, again at Midsummer in dry weather, with a third ploughing
before sowing at Michaelmas, thus attacking the successive crops of winter-
weeds, spring-crop, and summer-crop respectively. This method of 3 ploughings
held to the sixteenth century (Fitzherbert), and clearly entailed much
labour.*

A simple usage, maintaining a balance of the farm between the needs of
man and cattle, suggested wheat as the primary crop of first-rate food-material,
sown in the autumn, to be followed in the second year by inferior corn as
barley, a grass of shorter season, and hence sown in spring. The barley was
followed by a fallow the third year, grazed and ploughed, as the ' three-field '
system ; 5 maintaining one field in each state every year, and a 3-year cycle for all.

Rotation of Crops. The old fallow was merely a weed-heap, in which
indigenous grasses struggled with the alien flora of the wheat-crop. The
addition of grass-seeds would clearly hasten the process ; and these when
ploughed in at the end of the season, gave the essentials of an elementary
'rotation'. Clover (Trifolium repens) was added to the grass-seeds (sixteenth
century), following improved methods from Flanders, and in the middle of the
same century Red Clover (7! pratense) and Sainfoin became well known, as
also the field-cultivation of turnips for feeding sheep, introduced from Holland
about i65o.6

In order to maintain the balance of corn and cattle-crops it became
increasingly general to put turnips and clover between the two standing crops
of corn, so that the land was kept fully occupied ; the winter wheat and beans
being autumn-sown, and the others admitting a certain amount of cleaning in
the spring.

The great pioneer scientific agriculturalist, Jethro Tull of Berkshire,7
insisted on the importance of cleaning the land by hand-hoeing, and also by
the horse-hoe. For the latter he invented the 'drill' (1701), and cultivation in

Orr (1922), A Short History of British Agriculture, p. 30.
Orr, loc. cit, Ploughing with oxen in the Cotswolds, p. 94.
Orr, loc. cit., p. 6, Plan of a Manor Farm.

Plot (1705), p. 245, records three and sometimes four ploughings for wheat.
Plot (1705), loc. cit., implies that much land was still ' cast into three fields'.
Plot (1705), loc. cit., describes the use of Clover, Rye-Grass, Lucerne, and Sainfoin, but knew
nothing of turnips. J. Bobart sold Sainfoin seed at the Botanic Garden, 1690.
7 Orr, loc. cit., p. 56.

Crops and Weeds of Arable Land 81

line, as replacing broad-casting. He even grew 1 3 crops of wheat on the same
field without manure, by fallowing alternate strips in successive years.

Early in the eighteenth century, also, Lord Townshend founded the
< Norfolk Rotation', which did away with fallowing altogether, except as a
last resource in cleaning badly fouled land. Since by putting turnips after
wheat, the land could be hoed and thoroughly cleaned during the summer;
and the barley, as before, followed by clover and grass (especially Lolium
perenne) ; the last being ploughed in in the autumn. This 4-year system
remains the basis of all rotation of crops; the more so as, since 1886, the
value of green Leguminous crops has been increasingly recognized for increasing
the soil-content of combined nitrogen. Modern practice recognizes the great
drain of the soil by cereals, not only in combined nitrogen but in potash and
phosphates, and these substances may be added as chemical manures. The
rotation is also varied, or extended to 7-8 years, by adding another cereal
(e. g. oats), exchanging roots (turnips, mangel) for potatoes, keeping grass and
clover for more than one year, changing clover, which may be a failure, for
beans, or adding catch-crops after wheat for green fodder.

A general 4-course system of wheat, roots, barley, clover and grass, may
thus become on heavy land a y-year system of wheat, roots, barley, oats, clover,
wheat, beans, giving wheat the prominence in the succession, as it is the initial
factor.

The general principle of attacking the weeds in a low and spaced crop
is the essential basis of rotation, and makes it a paying proposition — keeping
the land under cultivation for food, and also maintaining a balance between
man and cattle. The more exact relation of the wheat-crop to the weed-
flora has been demonstrated at the Rothamsted Experimental Station.1
Wheat has now been grown (since 1 843) continuously on the same land with-
out manure, and with least fallowing. On the sample -| acre plot (Broad-
balk Field) the yield with no manure at all is still 12-13 bushels per acre, —
an estimated diminution of J bushel per year representing the deterioration
in the fertility of the soil. Continuous cultivation on an adjacent plot, with
manure, maintains a high yield (to 38 bushels per acre).

The present average yield for the entire world is given as 13 bushels
per acre. That of the Canadian wheat-fields 16 : — for Great Britain 30 :
for Oxford County 30 bushels and a ton of straw. The best land in England
will yield 40, and the maximum recorded is about 60. The present cost of
production runs to £15 per acre, as opposed to £$ 13^. in I9I4.2

It follows that fallowing is wholly unnecessary if the weeds are kept down :
even the Rothamsted plots, drilled at 10 inches, and hand-weeded in early stages,
are by no means 'clean', but show a considerable undergrowth of Poppies (1922).
A new method of attacking the weed-problem is afforded by the use
of Steam Tractors : these work more efficiently than the horse- ploughs, to
a greater depth, and cutting 3 furrows at a time do the work of 3 horse-
teams, or an acre in 4 hours. By such time-saving it is possible to get all
the ploughing done as soon as harvest is over, instead of letting it drag on
into or over the winter. By steam-ploughing in August or September, the
stubble is broken up ; and, following mild rain, the main crop of weeds
germinates, and may be destroyed by cultivation, before sowing. With
this improvement in methods of ' sterilization ', and the addition of suitable
manures, it will be possible to grow any crop, as required, at any time, and
the necessity for rotation also disappears.3

As compared with Wheat, Barley (Hordeum sativum) is still more xero-

1 Memoranda of the Origin, Plan, and Results of the Field and other Experiments. Rothamsted,
1900, p. 30.

2 Rothamsted Experimental Station. Abridged Report for 1918-20.

8 Loc. cit, p. 9. Where the ground is good and once clean, using clean modern seed, it is
possible to alternate wheat and beans indefinitely, as the weed-problem does not arise.

F

82 Plant-life of the Oxford District

phytic, as shallow-rooting, and making less demands on the soil. It produces
seed in a much shorter season, and can hence be grown where Wheat fails,
and farther north, or on poor land. It is commonly sown in the spring,
without special manure, and vegetates 3 months (May-July).1 The yield is
about 33 bushels per acre. Oats (Avena sativa) receive little special care,
but may be winter-sown hoping to avoid the fly. The average yield is 40
bushels. Beans are commonly winter-sown at 18 in. ; they may be hoed
when young, but are commonly neglected in later stages. Bean-fields give
usually the finest weed-display of any crop (especially tall red Poppies,
yellow Charlock, and white Radish). Hence Wheat following Beans is more
likely to be full of weeds, as well as of ' voluntary ' Bean. The crop averages
30 bushels per acre.

As an example of a root- crop, presenting a distinct habit of growth and
mode of cultivation, the Mangel illustrates the problem of obtaining late
feeding-material for cattle and for all kinds of stock, when other foods are
poor in quality, rather than for immediate human consumption.

The Mangel* (Beta vulgaris) is an artificially selected form of Beta mari-
tima^ a halophyte of the sea-coast, withstanding great exposure and summer
heat, so long as it has a deep source of water ; enduring salt soil, and hence
useful as a salt-storer, and taking any quantity of manure.

From the wild type which is indigenous, the cultivated form differs in the
biennial habit, the erect inflorescence-axis (3 ft.), and tendency to store food-
reserves in a greatly distended hypocotyl (showing above the soil) and the upper
portion of the root. Small greenish flowers are borne in sessile cymose
clusters of typically 3 (1-5), on the panicled inflorescence-axes. The single
seed of each flower is sclerosed up with the adjacent ovaries of the triad, to
a dispersal-unit thus containing 3 seeds. These are sown in drills 2 ft. apart,
at the beginning of May, and the seedlings singled out to distances of i ft. apart.
Under summer sun and heat, in well-drained ground with bottom water-supply,
growth is rapid, and the crop is matured in autumn; the roots being pulled
before severe frosts. The plant is thus given a working period of 6 months,
following the general scheme of indigenous vegetation from May to October.
The plants are spaced well apart, the vegetative habit being that of a basal
rosette, only making close canopy over the soil when growth is particularly
luxuriant. The rows may be kept perfectly clean by weeding ; but a new crop
of weeds begins to grow at any time after rain, the more in dry seasons when the
crop is stunted. Neglected fields may give a conspicuous weed-flora in autumn.
The average yield for Oxfordshire is 20 tons per acre of ' Yellow Globe '.

Turnips and potatoes as essentially * root crops ', growing in wide rows
which may be hoed and weeded throughout the early summer, and are matured
late in the season, follow essentially the same general lines ; and weeds may
follow abundantly as soon as weeding is checked. In gardens and allotments
potatoes will grow 3 ft. high, and flower, in dense canopy which cannot be
hand-weeded after Midsummer; but the growth is so dense that few weeds
can endure beneath it. Open fields are conspicuously foul. Neglected turnip-
fields in autumn may give a wide range of casual weed-flora, and are often
gay with blossoms. Turnips should give 1 3 tons per acre, potatoes 5 tons.3
It may be noted that the cereals and beans as standing crops take from
the soil large amounts of nitrogenous compounds, phosphates and potash,
for the production of seed-reserves, and return nothing. On the other hand,

1 Orr (1916), Agriculture in Oxfordshire, p. 198.

Plot (1705), p. 155, records for Oxfordshire a special strain of Rathe-ripe Barley which was
sown and harvested within 9-10 weeks.

The harvesting of the wheat is generally done with a self-binder using twine, which is estimated
to do the work of 10 men old-style : Plot describes the use of the smooth-edged reaping hook ; but
the sickle has been employed within living memory, or to about 1850. Oats have been seen cut with
a ' hook and a stick' (1922).

2 Percival (1910), Agricultural Botany, p. 360.

3 Orr (1916), loc. cit., p. 204.

Weeds of Arable Land 83

Root-crops, Mangel, Turnips (and Potatoes), not grown for their seeds, but
utilized at the end of a vegetative period, take comparatively little valuable
matter from the soil, but store photosynthetic carbohydrates as starch and
sugar. They usually add to the ground the material of their stems and
leaves ; and being fed to cattle, much of the material is also returned,
and tended in the form of farmyard-manure to the Wheat-crop. The
Mangel as a Chenopod, and the Turnip as a Crucifer, are eminently salt-
storing and halophytic by descent ; hence they will take any quantity of
manure, and what they do not use is also left for the next crop.

The Weeds of agricultural land may be classified from several stand-
points, more particularly as : —

(1) Grasses and herbaceous plants of pasture-land.

(2) Intrusives from woodland, hedges, and even from boundary-ditches.

(3) Aliens, largely annuals, imported with the seed, or introduced in

agricultural operations.

The special ecological factors involved as characteristic of the special
associations, may be distinguished as : —

(1) The provision of new and unoccupied ground in optimum condition
for the germination of seeds, and over wide areas ; hence inviting coloniza-
tion and open competition, to an extent far beyond anything under natural
conditions of the environment.

(2) The elimination of all arboreal forms and larger perennating stocks.
Ordinary herbaceous perennials are eliminated by ploughing ; only a few
residual types with particularly deep rhizomes or roots in the subsoil, or
with great capacity for regeneration from cut pieces of rhizome or root, can
remain effective. Owing to the great advantage gained by such plants in
open competition with mere seedlings, these may in time give rise to distinct
races of plant with special aptitude for this mode of existence, and thus
isolated by unconscious artificial selection (Dandelion, Carduus arvensis>
Convolvulus arvensiS) Triticum repens, Equisetum arvense).

(3) With total elimination of arboreal forms and the majority of
perennating stocks, the field is left open more particularly for the activity of
annuals in greatly increased ratio. The annual weed, in fact, becomes the
normal associate of the annual crop.

All field-crops, again, tend to be of annual duration, as worked in
association with marked annual rhythm of seasons, allowing the ground to
be wholly cleared of waste material at the end of each cropping, weeded,
manured, and re-cultivated to give full aeration of the soil. Perennial types
(Cotton, Castor Oil, Sugar Cane) are thus treated as annuals for purposes of
cropping in the tropics. Annuals are preferred, and the case of the biennial
turnip and mangel, utilized for their food-storage in the first year, only emphasizes
the point.

The essential factor of such association implies that the periodicity of
the weed should run parallel with that of the crop, and different crops will be
characterized by their special weeds ; though a wide range of plants may
attempt to adapt themselves to all. Thus Poppies may colour crops of
Wheat and Barley in July, so vividly as to be a feature of the landscape ;
but are kept down in root-crops by weeding. Rapidly developing Charlock
may colour wide ranges of young cereals bright yellow in June ; but may
similarly colour turnip-fields as aftermath crop in September.

From these general considerations it follows that : —

(i) New ground under favourable tillage may favour plants incapable
of holding their own in competition with other forms, in occupied land or
the small exposed areas permitted in a closed formation ; and such types
may persist under the special conditions without ever succeeding in estab-

84 Plant-life of the Oxford District

lishing themselves in any other. In this way, arable land may come to bear
a special flora peculiar to these fields, either predominant, or mingling with
residual and intrusive forms of the vicinity, and largely ' alien '.

(a) The greatest success in such association will ensue as the parallel-
ism of periodicity in crop and weeds becomes the more exact ; and this
will be increased by natural selection, as one type is favoured at the expense
of others in coincidence of germination, seed-maturation, and seed-harvesting.
The periodicity of each particular crop will be associated with a special
selection of weed-plants ; particular forms becoming characteristic, and
others less so, or residual, as the conditions of the main crop become more
precise or more narrowly exacting.

Thus Wheat (Beans and Oats), autumn-sown and flowering in late June,
as a tall shading crop, will be generally associated with a class of weeds
entirely different from those of Mangels (Turnips) sown in spring, with open
distribution, no special canopy, and pulled in late autumn, with little dis-
turbance of the weeds. Spring-sown Barley (Oats), as a tall crop with
dense canopy, rapidly maturing (July), may represent a third class of crop,
with its characteristic weeds, though combining features of the two pre-
ceding types.

But the subject is not so straightforward as this implies ; since one is
not usually dealing with plants growing continuously in successive seasons on
the same ground. If this were the case, the constitution of the association
would probably soon become obvious. Owing to general adoption of some
form of rotation of crops, the same field does not usually carry the same
crop for 2, years in succession ; and thus the weed debris of one crop becomes
the initial equipment of the next.1 New intrusives may be added with the
new seed, and a general mingling of weeds result. In such case, shading 2
and weeding in early stages are the determining factors. The greatest floral
display of the arable fields is given by non-weeded corn-fields in the early
stages of their growth (June, Midsummer), and again in the autumn fields of
root-crops. Casual weeds, flowering and fruiting late in the season, have no
chance in a corn-crop, but may grow freely with mangel (Chenopods, Poly-
gonum). On the whole, neglected root-crops give the greater variety of
species, though the corn-fields afford the greater display of individual forms
(Charlock, Radish, Poppy). The general list of corn-field weeds comprises
about 60 species.

A further source of complication is introduced by the manner in which
ploughing operations tend to bury seeds at some depth — these remaining
dormant through one or more seasons, to be again brought to the surface the
next time the ground is turned over. The consideration of the weeds of an
arable field then implies some knowledge of the condition of the crops for
several years previously. Each field requires to be taken on its own merits,
and over a period of several seasons, the appearance, disappearance, and
reappearance of special types being carefully noted. Data require to be
collected for (i) The weeds of the main crop ; (2) The special case of plants on
any road -track or way across the crop ; (3) The plants of the hedges adjacent
to the crop. These may be sorted out according to their prevalence in
successive seasons, and each field becomes a study in itself. The more
agricultural outlook further includes the collection of data showing the rela-

1 Seed-wheat is particularly well cleaned, and common weeds as Poppies, Lychnis Githago,
Charlock (Sinapis arvensis\ Sonchus arvensis, etc. , are largely residual from a previous Bean-crop.

2 Wheat sown in 6-inch drills gives a uniform mantle over the soil in early stages, and 3 bushels
of seed may be used on heavy soils. The same crop might be produced with half a bushel of seed
and more scattered plants. A close growth in early stages gives protection, as well as shading of
weeds. Broadcasting still gives a more effective smothering mantle : wide drills only encourage
weeds.

Weeds of Arable Land 85

tion of each particular crop to the weed-flora, as also the effect of varying
methods of cultivation and manuring.

The case of the perennial weed, and its possible eradication or intrusion,
requires to be considered separately for each case. Where such plants pro-
duce seed in the first season, they are on equal terms with the annuals.
But their method of perennation may have nothing to do with the reproduc-
tive periodicity. The case of 3 common species vi Equisetum (E.arvense, E.
fluviatile, E. Telmateia), all freely intrusive from adjacent ditches and damp
places, sufficiently emphasizes this point.

Root-crops are grown locally on heavy clay (Kimeridge, Oxford Clay),
alluvium, gravel-soils and Corallian : Wheat on all the higher sandy soils of
Greensand, Coral Rag, Calcareous Grit (Headington), Oxford Clay and
alluvium (Marston), and Kimeridge Clay (Littlemore). The complete history
of the weeds of arable land requires a detailed record of sample fields of
the different crops in rotation, on different types of soil-formation, continued
over several years. The most remarkable display of weeds, for size and
luxuriance, in relation to highly manured crops is shown on the Sewage
Farm (Littlemore).

Small Holdings and Allotments.

The case of the small holding follows that of arable land, as a condition
intermediate between that of the farm and the garden, in which the factors
of plant-association are further complicated by the addition of smaller crops,
as fruit-trees, vegetables and flowers of the market-garden, as also by a more
intensive condition of culture, by which more than one crop may be taken
off the same land in one season. Hence the case of the weeds as subsidiary
vegetation becomes more precarious ; exhaustive weeding may clear the
ground, and owing to the smaller area involved the labour question is not a
serious problem. On the other hand, the weeds become the more luxuriant
if weeding is neglected, and the condition of the holding may deteriorate
through lack of labour. Such land under private ownership, being less
accessible to the general public, may be left with the case of the private
garden growing plants of more decorative value under optimum conditions
of horticulture. The literature of Horticulture becomes a special subject,
as, in fact, also does that of the Allotment.1

More suitable for purposes of observation, since also more varied, are
the minor urban allotments which have grown up in the immediate vicinity
of the town, as a new and probably increasingly important factor in
the rural economy. The consideration of their weeds constitutes a special
case of those of arable land ; the new factors being that (i) the crops may
be harvested at any time of the year, thus providing unoccupied ground for
germination at any month ; (a) the crops may follow with any rotation,
giving greater possibilities of mixture. The general weed-flora tends to be
restricted to a few ubiquitous plants, together with stray casuals which come

1 The expression ' Allotments ' dates from the time when allotments were made to the labouring
poor at the general enclosing of common lands (1760-1845). Cf. Ashby (1917), Allotments and
Small Holdings in Oxfordshire, p. 1 3. ' Except as used for market-gardening or by expert poultry-
keepers, there is no method of culture which will carry a family on less than 30 acres.'

The term is now commonly applied to plots of 10-40 poles rented to urban population as plots
of ground away from the house occupied, for the purpose of growing vegetables. As an institution
such town-allotments began about 1891, and the area under cultivation increased considerably during
the war, taking in Playing-fields, and (temporarily) Merton Meadow. The oldest allotments
(Cripley) are now under distinctly clean cultivation, with much garden flowers, roses and ramblers,
to conceal the rudimentary architecture of tool-houses, etc., which constitute a conspicuous, if not
always agreeable feature of the suburban landscape.

For data of local crops, and typical scheme of management of such an allotment, cf. Elford and
Heaton (1919), The Cultivation of Allotments.

86 Plant-life of the Oxford District

and go, leaving little trace behind. Strictly speaking, there is not the
slightest reason why there should ever be a 'weed' at all in any well-
conducted allotment-area ; the facilities for checking their growth in manual
cultivation being sufficiently ample.

The amount of land locally under such allotment cultivation is already
considerable. The ground had been previously pasture-fields, cut for hay
(Donnington), grazed (Port Meadow), used for cricket grounds (CowleyRoad),
and largely flood-meadows of the alluvium (Osney, Botley), with attempted
raising of the level by means of town-refuse (Port Meadow). The oldest
tracts and those nearest the city are on the alluvium (Port Meadow Allot-
ments). The soil in these cases is Oxford Clay (Holywell), or with super-
imposed alluvium, or in the case of Port Meadow, alluvium over terrace-
gravel ; at Headington there are extensive allotments on Corallian soils.
In all cases the antecedent flora had been that of pasture-land ; and with
the clearing of the turf, grasses and the weeds of pasture remain to some
extent, in the borders, hedges, and foot-ways, while other weeds of cultiva-
tion and of human association are introduced. Since such intrusives may
become a nuisance, they are regarded as ' weeds ' to be kept down by the
cultivator in his own interest and also in that of his neighbours.1

Allotment-weeds are chiefly of annual duration (including ephemerals),
commonly growing up with the crop ; their maintenance depending largely
on the fact that their periodicity runs parallel with that of the cultivated
plant ; while weeding may be difficult in later stages of growth. With the
general run of summer annuals are included some particularly deep-rooted
perennials, surviving in virtue of a deep root or rhizome-system in the lower
layers of the subsoil, with great vitality and powe^ of vegetative propaga-
tion,— the cutting of rhizome or root into pieces by the spade only serving
to increase the number of individuals. It is a matter of interest to consider
the origin and possibilities of such a flora, its special means of perennation
and capacity for rapid multiplication, as much from the standpoint of the
remarkable vitality of such plant-forms, as from the converse standpoint of
the readiest means of effectively extirpating them. The special equipment
which enables such plants to hold their own comprises one or more of the
following factors : —

(i) Special mechanism of dispersal, preferably by wind.

(a) Special mechanism of perennation.

(3) Rapid rate of germination in open ground ; i.e. faster than the crop.

(4) Early flowering and seeding, also earlier than the crop, with prefer-

ably the monocarpic habit, as using up all available synthesized
material in the production of seeds, with extreme wastage-
coefficient.

While weeds of arable land may be graded according to their response
to ploughing in winter and spring, with two sets of climatic conditions,
allotment- weeds may be graded roughly in three such sets, according as :—

(1) They begin as seedlings germinating in spring (April, May) as the

first ' main crop '.

(2) Later crops of seedlings germinating in favourable rainy weather in

the early summer (June), and flourishing at midsummer.

1 Ashby (1917), loc. cit., p. 20, for general by-law. One derelict patch will infect a wide area,
and involve considerable unnecessary labour for better workers. Uncultivated allotments become
a forest of weeds in early June, already seeding and hiding the soil, and ground is commonly
neglected in late summer. Weeds are soon reduced if the waste-heaps, hedges, and foot-ways,
are properly looked after; this being considered beyond the province of the individual holder.
Some of the more obvious and objectionable forms should be definitely proscribed, and their growth
made a punishable offence. At present, plants only become illegal when they act as hosts to some
fungus ' disease ' of the crop ; but attention to a few common weeds for a few seasons might wholly
eliminate them from the district. The method has been tried in other countries.

Small Holdings and Allotments

(3) The late crop of September seedlings, germinating in the cooler
autumn months, after summer drought.

The first crop gives the summer ephemerals, as also the larger flowering
plants of the hot summer (Chenopods, Polygonums) as strays from a warmer
climate. The summer crop repeats a further set of ephemerals (Capsella^
Veronica} ; while the autumn crop develops a third set of ephemerals to
continue over the mild winter months, as also giving strong growths endur-
ing winter cold to flower in early spring ; many of these being perennials
which flower in the succeeding summer (Lamium album, Thistles, Docks).

A general list of 100 such plants,1 grouped according to their special
origin, indicates what is really the last stage of the weed-flora, as the
hardiest survivors maintaining a precarious existence under human assistance
and protection.

i. Pasture Grasses.

Agrostis alba (stolonifera). Festuca rubra. Poa annua.

Agrostis vulgaris. Holcus lanatus. Poa pratensis.

A lopecurus praten sis. Hordeum t>ratense. Poa trivialis.

Bromus mollis.
Dactylis glomerata.

Festuca rubra.
Holcus lanatus.
Hordeum pratense.
Lolium perenne.
Phleum pratense.

2. Herbaceous perennials of the pastures.

Achillaea Millefolium*
Bellis perennis.
Chrysanthemum Leucanthe-

mum.

Geranium molle.
Leontodon autumnale.

Leontodon hispidum.
Medic a go lupulina.
Plant a go lanceolata.
Ranunculus acris.
Ranunculus repens.
Rumex crispus.

3. Climbers and Trailers from Hedgerows,
Solanum Dulcamara. Galium Aparine.
Calystegia sepium.

4. Plants of the Roadsides and Waste.

Bromus sterilis. Pastinaca sativa.

Capsella Bur sa-pas fort's. Plantago major.
Daucus Car of a. Potentilla anserina.

Hordeum murinum. Lapsana communis.

Melilotus officinalis. Potentilla reptans.

5. Human associates.

Chenopodium album.
Chenopodium urbicum.
Chenopodium poly sper mum.
Polygonum Persicaria.
Polygonum lapathifolium.
Polygonum aviculare.

Senecio vulgaris.
Senecio squalidus.
Stellaria media.
Cardamine hzrsuta.
Diplotaxis muralis.
Anthriscus sylvestris.

6. Weeds of arable land.
(Voluntary) Wheat. Alopecurus agrestis.
Barley. Sonchus asper.
Oats. Fumaria officinalis.
Sonchus oleraceus. Etiphorbia Peplus.
Anthemis Cotula. Euphorbia Helioscopia.
Matricaria inodora. Sonchus arvensis.

7. Casual Aliens of no fixed tenure.
Solanum nigrum. Mercurialis annua.
Trifolium arvense. Scandix Pecten- Veneris.

Taraxacum officinale.
Trifolium minus.
Trifolium pratense.
Trifolium repens.

Nepeta Glechoma.

Rumex obtusifolius.
Sisymbrium officinale.
Urtica dioica.

A triplex hastata.
Atriplex patula.
Urtica urens.
Lamium album.
Lamium purpureum.
Lamium amplexicaule.

Veronica Tournefortii.
Veronica hederaefolia.
Polygonum Convolvulus.
Raphanus Raphanistrum.
Sinapis arvensis.
Papaver Rhoeas.

Aethusa Cynapium.
Chrysanthemum segetum.

1 The list is not exhaustive, and the sub-sections are somewhat arbitrary ; but it is intended to
include the commoner forms found growing in local allotments, and to indicate a method of sub-
dividing a mass of types into more convenient ecological groups.

88 Plant-life of the Oxford District

8. Garden Strays, of casual occurrence.

Reseda odorata. Mentha viridis. Foeniculum officinalis.

9. Residual Swamp-flora.
Typha latifolia.

10. Specially deep-rooted or rhizomatous plants, defying extirpation.
Convolvulus arvensis. Agropyrum repens. Polygonum amphibium.
Circaea lutetiana. Carduus arvensis. Ranunculus Ficaria.
Aegopodium Podagraria. Tussilago Farfara. (JEquisetum arvense).

As in the case of arable land, the chief interest of the botanist centres
in such despised weeds, rather than in the crops of the allotment-holder, —
the former presenting the greater variety of habit and organization, as also
being entirely on their own, and fighting the last losing battle against domina-
tion by man, — the latter, on the other hand, comprising tame and domesticated
races, spaced each in their own ground, wholly dependent on human assis-
tance for their origin and racial progression, and in a majority of cases never
working out their reproductive cycle, but cut or ' pulled ' as the * crop ', when
they attain a certain stage of vegetative maturity ; to the extent that the
life of a cabbage becomes a byword of biological reproach.

Waste Heaps and Derelict Ground. The debris of a modern town
includes an enormous amount of waste material, the rejectamenta of the
human population and dwellings, as ruins of buildings, collections of brick-
bats, stones and soil, to which is added in the present generation, stores of
paper, tin cans, broken glass and rusty iron. Such rubbish-heaps, casually
manured, with little good soil, but effective drainage, constitute a nidus for
weeds of all descriptions.

These differ from the case of gardens and allotments, in that the intru-
sive plants are not going to be eradicated ; but, if anything, are regarded as
the happy solution of the problem of hiding such waste from sight ; at any
rate, with the result that the sordidness of the landscape is less obtrusive in
the summer than it is in winter, as the material becomes increasingly hidden
beneath a mantle of something green. None of such waste-heap flora
attains any conspicuously aesthetic value, though screens of Privet, annual
Impatiens Roylei and Scarlet Runner Beans are freely employed in garden-
construction. Such waste-heaps present ground which may be unoccupied
at any period of the year, usually amply drained, though with feeble water-
supply, commonly of fouled soil and hence suitable for colonization by
representatives of the more characteristic families of salt-storers and xero-
phytes (Chenopodiaciae, Polygonaceae, Cruciferae, Caryophyllaceae) ; and
annuals of these groups are commonly the first invaders to take control of
the new site. Being commonly near human occupation, and in sheltered
situations, they afford a sanctuary for refugees of all kinds, as escapes from
garden-cultivation, and alien weeds of a warmer climate vegetating in the
hot summer. Hence such localities become the happy hunting-ground of
seekers after * adventives '. Almost anything may grow on a waste-heap
from huge plants of Helianthus annuus (giant strain, capitulum 22 in. diam.)
to Cucurbita, Datura Stramonium (setting 75 capsules), Zea Mais, Wheat,
and even Phoenix (germinating from casual date-stones, in quantity, to the
3rd leaf).1 The first annuals, as Poa annua, Capsella, Chenopodium album,
Polygonum aviculare, give place to Nettles, Docks, Plantains, coarse grasses
(Dactylis, Bromus sterilis, Hordeum murinum, Agropyrum repens), and a wide
range of types soon get together as samples of a struggling flora, which come

1 Town waste, utilized as the basis of allotments in Port Meadow and Osney allotments, gives
large numbers of Apple, Pear, and Cherry seedlings, some of which have grown to fruiting trees.
Perhaps the most interesting case is the large number of Tomato plants coming up among the
Mangels, and even in the hay-grass of the Sewage Farm.

Waste Heaps and Derelict Ground 89

into active competition for water and free room to develop. As the perennat-
ing stocks accumulate dead leaves and dust, worms become active, the soil
grows, and in a few years the debris may be completely covered with a weed-
vegetation which is in turn dominated by grasses, and in the course of time
will give turf of grass-land ultimately regressive to thorn-scrub (cf. Rubbish
heaps of Headington Quarry).

The stages in such a progression afford an interesting study from the
point of view of the time taken, and the use of such vegetation in the often
insistent problem of covering up the inevitable waste of civilization.

As a special case, more removed from the immediate vicinity of human
occupation, may be included the Hayrick Site. In all pastures cut for hay,
the usual practice is to have the rick in the corner of the field most avail-
able for transport, to save labour at harvesting. Hence in most hay-fields
there is a space marked off as a site for one or more ricks, as the crop is cut
in successive seasons, and is not necessarily sold or utilized. The fate of
such areas affords a few points of interest. Originally taken as the most
convenient, and in low-lying meadows the highest spot for the sake of drain-
age, and often built on a brushwood bottom, the rick begins by wholly
killing off the plants beneath it ; and when it is removed, presents not only
a denuded area, but one well-enriched with accumulated debris and the
washings of the waste. As soon as the site is exposed for new colonization,
it is covered by a particularly luxuriant growth of weeds ; and such sites
become the best grounds to search for local intrusives and samples of the
weeds in the fields around.

Rank growths of Nettles, Docks, Chenopods, Atriplex, Polygonum, Seneczo,
Taraxacum, Poppies, Plantains, Raphanus, Sinapis, Arctitim, and Carduus,
spp., are especially characteristic, with equally luxuriant grasses as Dactylis,
Arrhenatherum, Alopecurus, Agropyrum, Phleum, etc., all doing so much better
than in the open pasture, that they attract attention, and one visits such
localities to find species making good specimens. These sites are often
strikingly conspicuous in the summer, affording a blaze of scarlet Poppies,
yellow Charlock, white Radish, and mauve Carduus arvensis^ in close association
with adjacent arable crops which may be fairly clean, and for which they provide
a continuation of the weed-flora. These give place to biennials, flowering the
second season, and perennials. Keck, Thistles, Docks, Heracleum, long hold
their own, though the grasses become dominant in the long run. Mowing will
put an end to the larger growths more rapidly ; and if seedlings of thorns are
kept down, the site returns to normal pasture in the course of time ; though it
may be long marked as a slightly raised area on which the grass grows stronger
and of a deeper green.

Corresponding stations based on manure-heaps of arable fields, or general field-
waste, may present similar phenomena in an exaggerated form. But such
plants of cultivation and aliens do not invade the pastures.

90 Plant-life of the Oxford District

River and Ditch Flora.

The control of the aquatic vegetation is less marked than that of the
land-surface exploited for crops ; but effects due to interference in special
cases follow the normal ecology of ponds and ditches, where these are to be
drained, or partially cleaned to maintain the flow of the water ; as even
the locked river may be let out in sections when the locks are being
repaired or enlarged, and a channel is kept free of weeds for navigation.

Cleaning the main river takes place in late summer, or when the vegeta-
tion has reached its maximum (July-Aug.) ; enormous quantities of weed
being collected into barges, the cutting being effected by pulling a drag-
knife over the bed of the stream. Notices by the Thames Conservancy
prohibit such weeds being left where they may decompose and contaminate
the water. The material, collected to the extent of many tons, includes
dense growths of trailing Pond-Weeds (Potamogeton lucens, perfoliatus,
pectinatus, etc.), together with stretches of submerged leaves of Sagittaria^
Scirpus lacustris, to a less extent of Oenanthe fluviatilis and Elodea, as well
as intrusive vegetation from the bank-side, cut by hook (Sparganium
ramosum^ Acorus Calamus^ and rhizomes of intrusive sub-aquatics as
Epilobium hirsutumy Lycopus, Agrostis stoloniferd). As these plants are
largely rooted in a gravel bottom, such cleaning does little to affect the
buried rhizomes, and little damage is really done to the flora ; the vegetative
growth being renewed on a cleared site in the succeeding season.1

Branches of the river utilized as Mill-streams (Wytham and Osney Stream,
The Old River) were formerly kept clean by weeding once or even twice in
the course of the summer. Now they are much neglected; the town-mills
are supplied with water taken off at Medley, and others have auxiliary power.
Such streams, left uncleaned, fill up with dense growths of Sagittaria, Spar-
ganium ramosum, S. simplex, together with Nuphar and luxuriant intrusive
bank-growths of Epilobium hirsutum, Rumex Hydrolapathum, Stum angusti-
folium, Carices and Scirpus, or may be readily blocked by fallen Willows.
When wholly neglected and stagnant, they give Batrachian Ranunculi, and
a dense mantle of Lemna-forms (L. minor, L. trisulca, Spirodela polyrrhiza).

When kept well-cleaned, providing a good fast-flowing stream of clear
water over a gravel bottom, such ditches produce a quite distinct flora, vegetating
actively in early spring, and filling up with a dense growth, as banks of
Callitriche verna (3-6 ft.), stretches of submerged Ranunculus trichophyllus,
with Oenanthe fluviaiilis, Elodea, Myriophyllum and Ranunculus fluitans ; as also
algae as Chara, Vaucheria and Enteromorpha intestinalis in long trails (3-6 ft.).
A good example is afforded by the Railway ditch alongside the Willow Walk,
when cleaned out in summer and giving a new crop of clean aquatics over the
mild winter-months.

As an example of a wholly artificial construction, the City Reservoir,
adapted from pits formed by removing ballast-gravel to make the Railway
embankment, at Hinksey, is of particular interest. In late summer it commonly
affords a remarkably beautiful collection of wholly subaqueous vegetation,
growing in fairly still clean water, at a depth of 6-10 ft. When the surface
is quiet and the sun shining brightly, massed growths of submerged leafy shoots of
Callitriche, Oenanthe fluviatilis, Myriophyllum, and Nuphar, are shown, together
with the vertically erected foliage-trails of Potamogeton lucens, P. perfoliatus, and
the similarly erected cable-petioles of Nymphaea alba (alone flowering at the
surface), also the conspicuously erected foliage of submerged Scirpus lacustris
and the ribbon-leaves of Sagittaria.

1 This is particularly striking in the case of Nuphar, the stout rhizomes of which form a solid
mat at the bottom of the stream, and only the leaves and flowers are cut away.

The Regression of Cultivated Land.

Recognition of the fact that the general aspect of the landscape of
the modern countryside expresses the modifying effect of human activities
on the original flora, continued along closely similar lines of copse, wood-
land, pasture, water-meadows, and arable land, for a period of at least
several hundred years, leads to the suggestion as to what would happen
if cultivation ceased, and the land were allowed to lapse again to a wild
state. In how many years, for example, would land go back to the con-
dition described as primitive woodland ? The problem may be approached
from several standpoints : —

(1) The reversion of wet flood-meadows and fields of the alluvium.

(2) The regression of dry hill- pastures.

(3) The regression of fields on clay (Oxford and Kimeridge), or on

low gravel-terraces.

(4) The colonization of waste-heaps, including quarry-banks, already

indicated.

(5) The complete covering of ruins, and all remaining traces of human

occupation.

Examples of all these phenomena are of general occurrence, and from
them it is possible to obtain an idea of what would happen if the entire site
of Oxford became derelict, and vegetation again asserted itself.

The first case is afforded by the neglect of hay-pastures and dry fields
affording little feed for cattle. The clean grassland of the meadow flood-
area, and of hay-fields generally, is maintained by the agency of annual
mowing, whereby the shoots or seedlings of woody plants (Elm, Poplar,
Thorn) are kept down, as are also the late summer-growths of thistles of
the dry season. Flood-meadows are subject to free invasion from the hedges
by suckers of Common Elm and Gray Poplar, for a distance of 20-50 yards
from the tree, and these as a rule are not touched by grazing cattle. In the
same way damp clay pastures produce 'seedlings of Crataegus, and such
thorny shoots are also avoided by cattle, growing 2-3 ft. in the first two
years if not mown over. Hawthorn is followed by Rose-briars, by intrusive
Sloe from the hedges, locally by Ononis spinosa^ and to a much less extent
by Rubus which prefers leaf-mould. All these plants are spinous and are
rejected by cattle. As the larger forms become shrubby, cattle graze
around them, thus rounding off the bushy growths to compact oases of thorn-
scrub. Where there is no grazing the thorn-growth may be fairly uniform,
soon becoming impenetrable.

Good examples of the first stages of Thorn-scrub are afforded by poor
pastures on Kimeridge Clay (Iffley, Sandford Brake, Cumnor Hurst), and on
Oxford Clay (Binsey). The derelict Marconi Station on Cumnor Hill (Coral
Rag)» gave cl°se thorn-growth to 5 ft. high in 3 years, having been sown from
an adjacent hedge by strong winds for a distance of 50 yards.

The thorns may thus give isolated tall bush-growths, 10-20 ft. high, with
little else but Briars and Brambles (Headington Quarry, Magdalen Bridge
Scrub) ; soon becoming impenetrable where grazing is wanting (Chawley Hurst
Scrub, Sandford Brake Scrub); the ground-flora of grasses and herbaceous
plants being comparatively little affected until canopy is complete.

With the action of cattle in ' rounding off' the patches of scrub, other
plants are protected at their margins, afforded free light, and incidentally
manured ; Nettles, Thistles, Solatium Dulcamara, rough grasses of the hedge-
rows, Bromus asper, and Umbellifers as Anthriscus sylvestris, Heracleum
Sphondylium, Torilis Anthriscus, reproduce the flora of the Hedge-associations,
and further stages follow the general lines of regressive woodland. Good

92 Plant-life of the Oxford District

examples of the drier well-drained stations are seen at Headington Quarry ;
in the damper levels of the alluvium, Elm, Ash, Poplar and Willow follow
on in the course of time.

Dry high pastures on light sandy soils produce Gorse and traces of
Heather (Pickett's Heath, Bagley Wood), but the latter is conspicuously defi-
cient in the district, and even Gorse is scanty. Wet, low-lying undrained tracts
produce fancus, also dominating the ground-flora ; butjuncus, owing to its close
growth, affords little opportunity for the germination of tree-seedlings. Willows
and Alder are more usually added as they germinate at the flood-line on river
and ditch-bank.

An interesting example of the later stages of Thorn-scrub, with Bracken
and broad-leaved trees, is seen at the University Enclosure, Shotover, no longer
grazed. In many parts the tree-canopy is making close-contact, and the
Bracken is dominant in 'the interspaces. To the trees are added Ash, Oak,
Sycamore. The progression has been hastened by the planting of additional
forms (Pinus, Populus, Pyrus Aucuparia, P. Aria), but these are still small,
and the effect of Oak-Bracken Woodland, with its usual associates and sub-
dominants, is within reasonable view, so long as it is let alone.

Although the general phases of retrogression can be thus indicated by the
comparison of local examples, direct observation and record of special tracts
over a period of many years will be of greater value. It is in this respect that
departmental organization is essential. It is in fact the business of a Botanical
Department to keep such a record of local changes, probably never so rapid
or far-reaching as at the present time, by which the general aspect of the
surrounding country has been completely changed within living memory.1

1 To those who mourn the past rather than praise the present, the verses of Matthew Arnold
afford a melancholy review of changes for the worse. A more progressive generation will acclaim
the great increase in the population, with associated gas-works, water-works, railways, market-
gardens, allotment-areas, not to mention the new Corporation and Rural Council houses, the tarred
roads and the fast motor traffic, which now dominate the outskirts of the City.

There is little detailed information as to the condition of plant-life in the district in early times,
beyond a few references in Plot (1705), and what can be gathered from Sibthorp (Flora Oxoniensis,
1794), with the localities given for a large number of forms now extinct.

Mediaeval scholars entered Oxford over Shotover, down a horse-path through the thick forest to
Magdalen Bridge and the East Gate of a walled city. Even the traditional Oxford Country of
Shelley and Matthew Arnold in the early nineteenth century has been greatly changed during living
memory, and it will be probably increasingly improved by speculative building in the next fifty years.

Since 1850, the introduction of the Railway, by solving the problem of food-transport, in
quantity far beyond the capacity of the local area to supply, has affected local architecture, as well
as the general conditions of agriculture. Until this time, Oxford was still in its main aspect a
mediaeval city ; on all sides, except where it touched the railway, the city area terminated abruptly,
and one came suddenly to meadows. The poorer streets were faced with wash and ' pebble-cast '.
Beyond Magdalen Bridge, Iffley Road was bounded by corn-fields, and unenclosed meadow stretched
to Littlemore.

Children no longer gather violets in the Iffley Road, within sight of Magdalen Tower ; nor do
budding botanists seek ' the lone alehouse in the Berkshire Moors '. Surrounding villages and farms
(with few exceptions) express rather the decadence of an older system of agriculture than any modern
efficiency. It is already curious to read of Dr. T. Arnold (1819) expressing a wish to take ' one
more look at Bagley Wood, and the pretty field and the wild stream that flows down between
Bullingdon and Cowley Marsh ', or ' the little valleys that debouche on the valley of the Thames
below the Hinkseys'.

Two well-known elegiac poems of Matthew Arnold— 'The Scholar-Gipsy ' and 'Thyrsis' (1861) —
are valuable as depicting, among a somewhat muddled blend of- classical allusion, the general aspect
of the open country around Oxford in the early nineteenth century. A tree is still pointed out as the
' Glanvil Elm ', ' Umbrella Tree ', or Matthew Arnold's ' signal tree ', a conspicuous landmark on the
hills to the west ' bare on its lonely ridge '. A favourite walk of this time was to follow the old
pack-horse track straight up from South Hinksey over Boar's Hill to Wootton and Besselsleigh.
On turning down Lake Street from the Abingdon Road, this tree is curiously centred at the end of
the vista of small houses and the Waterworks, and on crossing the ' Lake ' (City Reservoir), and the
Railway (by 'Jacob's Ladder'), is still straight ahead on the edge of the ridge. Passing over the
causeway ('Devil's Backbone') to South Hinksey, and going up through the crops (mangels,
potatoes, and barley) of the small holders, the tree is again centred at the top gate to the ' Happy
Valley '. The path continues past Chilswell Farm, rising over the hill (400 ft.) formerly used as
a Golf-course, and ahead will be noticed a conspicuously isolated tree, standing out against the sky,
in the hedge- waste about 1 50 yds. left of the foot-path.

The tree is a tall, badly stag-headed Oak, pillared with epicormic shoots, the trunk 2 ft. in

Regression of Cultivated Land 93

As examples of minor changes, affecting easily accessible stations
within the current year, may be instanced : —

The Fencing of ' Open ' Brasenose : The extension of the Golf Course
over Lye Hill, replacing pasture and arable fields: The cultivation of
Bullingdon Bog Valley, and the drainage of its lower portion : The
Reconstruction of Iffley Mill Weir : The clear-felling of a quarter of old
Wood (Milestone Piece), Bagley Wood : The extension of allotments at
Manor Road (flood-pasture) : The Council Houses in Iffley Road, Cowley
Road, Abingdon Road, replacing pasture fields: The New Loop and
extension of building at Iffley Turn, in pasture fields : The reconstruction
of the Railway Bridge over the Thames, with denudation and remaking
of embankments : The first appearance of a notice against Trespassers on
' Private Land ' of a meadow in the Iffley alluvial area, as also on the
scrub-covered rubbish-heaps of Headington Quarry.

The conventional notice, which has no special legal significance, may
be merely a crude threat to unwelcome strangers, or a method of evading
responsibility for their welfare ; but often merely expresses a dog-in-the-
manger type of mentality, and the addition of barbed wire is a deliberately
unfriendly act.

VII. ALIENS AND ADVENTIVES

By an alien is conventionally understood a plant which is known to
have been introduced by human agency, or preferably a plant which is
associated with human occupation of land. The term is wholly metaphori-
cal, and like other metaphorical expressions is likely to be misleading.
To previous generations the general idea sufficiently distinguished between
plants which were assumed to be 'native' or * indigenous' to the country,
and others which came in from foreign sources ; this general impression
following from the conception that native plants were created, or at any rate
' evolved ' in the land where found. The fact remains that all plants in this
country are immigrant at some time or another ; the expression alien is
purely relative, as applied by the race in possession to the race that is
coming. The Englishman who assumes that he is a native of this country
was as alien to the older Celtic races, as any representatives of the interesting
civilizations of Central Europe may be to us at the present day. So long as
the period of human occupation of the land was considered from the stand-
point of the historical epoch of 2,000 years, the term alien merely expressed
a plant of which there was some evidence of introduction during that period.
With the extension of the time during which man is known to have lived in
this country to something like 50,000-100,000 years, the subject takes on
a much wider aspect.

Older attempts at analysis of this problem have attempted to grade
plants as native, denizen, colonist, alien,1 according to degrees of establish-
ment ; and the term alien is generally retained to cover all the cases of forms
which have come in with the aid of man, to become more or less naturalized.
The term ' adventive ' conveniently meets the case of those whose importa-
tion is so casual and so recent that they have so far not had time to show

diameter. One comes immediately to barbed wire, the cultivated arable fields of Pickett's Heath
and houses. The track continues on for half a mile to meet the main road at Hill Crest (500 ft.),
and a pilgrimage of disillusion ends appropriately at the « Boar's Hill Shop ' (Howard and Nicholson,
Licensed to sell Tobacco and Methylated Spirit). There is no other ' signal elm that looks on
Ilsley Downs ', and the spirit of the generation that prompted these lines is now something less than
the shadow of a dream.

i Watson (1847), Cybele Britannica, p. 63.

94 Plant-life of the Oxford District

what they can do. The subject of aliens in the widest sense is of special
interest, as it opens up views of the migration of plants, and the complex
factors involved in determining the chances of their failure or success in
becoming established.

Bearing in mind the original condition of the country, as covered with
dense forest, bare heaths, and downs, populated with the slowly returning
representatives of the deteriorated post-glacial flora of Central Europe, it
would appear that all special pasture-plants, all the weeds of arable land, all
crops, garden-plants and flowers, as well as many valuable timber-trees, are
open to the suspicion that they have been at some time intentionally or
unconsciously introduced by man. The difficulty will consist in isolating
such forms when well-established, and the records of the historical epoch are
of more definite value. On the other hand, historical references are often
merely negative, as suggesting that the plant was not commonly known to
the writer before a certain time, and usually to one whose botanical know-
ledge of the country as a whole may have been extremely incomplete.1

The simple lines of alien migration may be checked from the behaviour
of common garden-plants of known introduction. Thus Euonymusjaponicus,
a common evergreen, does not flower locally, although it does so freely in the
S. of England by the sea ; other plants are cultivated because they flower
freely (Jasminum offidnale^ J. nudiflorum, Forsythid), but never, or only
very exceptionally bear fruit. Other plants appear to fruit, but the seed is
imperfect or wanting (Populus nigra, Liriodendron). All such plants are
evidently introductions which will never make good ; they remain dependent
on the hand of man, and require to be propagated vegetatively, unless grown
from imported seed. All trees and plants similarly non-flowering, non-
fruiting, or producing only occasional seeds, even if found growing remote
from cultivation, must have been similarly introduced at some time. Even
in the case of plants occasionally fruiting, there is the further problem of
seed-wastage, and the question whether the amount of fertile seed produced
is sufficient to cover such wastage of dispersal and germination under com-
petition ; that is to say, in any indigenous plant seed must be produced in
great profusion. A chance for long-continued survival is afforded to plants
which have already attained a method of ready vegetative propagation,
which will multiply individuals without affecting the race. Thus the
Common Elm and the Gray Poplar (Populus canescens)^ which flower freely,
but do not produce fertile seed, may maintain their station practically
indefinitely by copious growth of suckers. Other herbaceous perennials
which flower but never fruit, of known introduction, may in virtue of an
efficient rhizome- system, defy extirpation (Aristolochia Clematitis), or carry
on indefinitely where not interfered with ( Vinca> Helleborus foetidus, Acorus) ;
and this applies particularly to ' bulbous ' plants as the Snowdrops, Crocus,
and Narcissus (sp.) of garden-cultivation. All plants which fail to produce
seed at all under natural conditions, are clearly of alien origin ; since they
could not have come to the country by the ordinary agencies of seed-
dispersal, except as individuals rather than as a race, and for these the case
is so far clearly recognized.2 But the subject takes on a wider range, and
the main principle may be approached from another standpoint.

Great Britain over a northward extension of some 600 miles presents
a marked range of climatic dispersal. Many types are fully successful in
establishing themselves by seed, as apparently ' indigenous ' in the South,

1 Thus Caesar recorded that neither Beech nor Fir grew in Britain (54 B. c.), De Bello Gall.,
v. 12.

* Dunn (1905), Alien Flora of Great Britain.

Aliens and Adventives 95

which are unknown in the wild state in the North (Beech, Hornbeam,
Viscum), although they will grow if planted. That is to say, somewhere
in Central England they are on the verge of their northern distribution ;
implying that under these conditions they are unable to mature in successive
seasons enough seed to counterbalance the increasing wastage of natural
selection ; and thus the race tends to die out, although individuals may long
continue. Any condition which will ease off this wastage will make all
the difference in survival. Among such aids may be included : —

(1) The utilization of perennation-mechanism (bulbs, rhizomes, resting
buds, etc.) which enables the individual to tide over an unfavourable season,
and so have a new chance of seeding.

(2) The utilization &f fruiting-years in a climate with increasingly short
working-period, as the plant may produce abundant seed in one season, but
practically none in others ; a common phenomenon in indigenous trees
(Apple, Oak, Finns), the more marked as the plants are at their critical
range (Beech, Hornbeam).

(3) Assistance in dispersal to new stations by alien animals, other than
those naturally indigenous (sheep, pheasants), and equally artificially main-
tained, or present in larger numbers owing to human protection (cattle,
rabbits), including also unconscious dispersal by alien man himself (on
clothes, boots, cart-wheels, etc.).

(4) Above all the increased provision of unoccupied ground, in which
seeds may germinate under greatly reduced competition with other plants,
or without any at all. This case follows the effect of human agency in
clearing the ground, the felling of the forest, the ploughing of arable land,
the making of hedges, cuttings and ditches, or the habitual destruction of
any adjacent plant-life.

That is to say, apart from any question of intentional importation, the
occupation of a country by man eases the wastage-problems for a large
number of plants on the verge of their distribution, and with this slight
assistance they may go farther north than they would otherwise, or be kept
alive in what must be really artificial surroundings. The case is the more
exaggerated when such plants acquire some economic significance, and are
intentionally planted and * nursed ', in order to reduce still further the
wastage-factor. Thus Beech grows in Scotland when planted, and so does
the Mistletoe, but they do not become established : so far, these plants are
alien in the North, though classed as fully indigenous in the South. Wild
plants of the south may pass with slight assistance to grow associated with
man in Central England, though becoming rare casuals in the North, in
cultivated or cleared ground, before they finally disappear. The question
as to whether a plant is marked as alien or not in the general British Flora,
has little reference to the constitution of the flora of a small district;
political terms being confused with geographical.

With a wider range, the same generalizations hold for the relation of
Great Britain to Continental Europe and the warm Mediterranean Region.
Common plants of the last, with similar human assistance,may extend to Central
Europe, in association with man, as weeds ; and these may pass similarly
to the South of England as short-season summer-annuals in cultivated land,
wholly incapable of existence in open competition with the indigenous
flora ; becoming increasingly casual farther north, until they meet a climate
in which they either fail to mature seed in the short season, or in which
even an enormous output of seed fails to meet the wastage. That is to say,
freed from competition with other vegetation in unoccupied ground, the
weeds of a warm climate may follow migrant man until they are cut down
by factors which are climatic rather than biological. In this way, human

96 Plant-life of the Oxford District

migration brings with it a long series of unconsciously imported aliens as
associated, rather than ' introduced ' weeds of pasture and arable land, as
also of waste-heaps and dung-heaps, which soon become the commonest
types of the new flora, evicting the previous natives from those stations, as
the conditions are the more divergent from those of the original formation.

Such importations may also come into direct competition with indigen-
ous plants occupying similar stations ; and thus representative species of the
same general character, and derived from different districts, may be found
in increasingly mixed association. For example, where three or more closely
' allied ', or apparently similar types of one genus occupy the same sort of
station, it is probable that two at least are aliens : — cf. the remarkable ' sets '
of Thistles, Chenopods, Polygonums, Veronicas, Euphorbias, and Poppies of
arable and waste ground. Much the same applies to the more definite
introductions of man for food or economical purposes. The Wheat of
Western Asia, cultivated as an annual, requires to be sown in the previous
autumn, and runs out before reaching the North of Scotland. In Orkney
the only cultivated cereals are Oats and the 4-rowed Barley (Bere), and this
in late seasons may be only harvested by November.

Taking this long-continued northward drift of the plants of the Old
World area from Post-Glacial times, it is evident that no plant of S. Europe
is now ever likely to establish itself in open competition with indigenous
flora, however much it may apparently succeed with only slight assistance,
or in the milder climate of S. England by the sea, where frost is practically
eliminated. Thus Sycamore comes up freely as a weed in the West of
England, in garden-ground and underwoods, but less in natural woodland,
and not freely in gardens, in the Oxford District. Veronica Tournefortii
has established itself in all cultivated land, within the last hundred years,
but only in competition with other Veronicas of the same alien type
( V. agrestis) ; as Crepis taraxacifolia, locally common in grassland, replaces
other alien forms of Crepis (as C. biennis) 1 in waste-places where unoccupied
ground may be artificially provided.

From these standpoints aliens may be graded according to the degree and
amount of assistance gained from human occupation of the land as: —
(i) Assisted (a), the case of plants just holding on at the limit of their dispersal
area, with the slight unconscious help of man in providing denuded ground, or
taking seeds (e.g. Clematis). (2) Assisted associates (aa), plants normally
indigenous, but owing their great and special development to the increased
area in which they find suitable conditions (Buttercups, Daisies, Dandelions).
(3) Assisted associate aliens (aaa), plants accompanying man in distant migra-
tions, now so common and abundant as to pass for indigenous (e. g. Chenopod-
ium album, Polygonum Persicaria), not establishing in normal pasture, nor in
woodland. (4) Assisted associate alien adventives (aaaa), including chance
casuals, coming in at any time, found only in cultivated or waste ground,
not establishing, and usually not found in the same spot in successive seasons.
It is also obvious that no sharp line can be drawn between such grades, but
the consideration of numerous special cases may be interesting on their own
merits.

On the other hand, plants coming from a botanical district so remote
that there is no chance of dispersal by natural agencies, may be able to
compete with indigenous flora on their own ground, and even to become
invasive. The remarkable case of Elodea, brought from Canada about 1842,
and long a pest in streams and ditches, shows what can be done in this
direction, even by vegetative propagation alone, the introduction being a
carpellary plant.2 Hence there is so far no reason why plants from the

1 Cf. Dunn (1905), Alien Flora of Great Britain, pp. 113, 149.

a Weeping Willow, carpellary only (1730) ; Populus serotina (1787), Lombardy Poplar (1758)
staminate, are all also the product of a single introduced individual.

Aliens and Adventives 97

New Zealand Alps and uplands, for example, once they have been given
the initial assistance required to bring them, should not prove successful,
and dominate the English Hills.1 It is, however, interesting to note that
none of the modern introductions of the N. Temperate zone from Japan,
N. America, and California, brought for timber or decorative effect, have
gone beyond the condition of casual escapes (Aster, Solidago, Lupinus^
Aquilegia, Escholtzia^ etc.), though Oenothera and Mimulus may be referred
to as locally naturalized in the south and by the sea. Also one wonders
what is wrong when the finest forest-trees of N. America and Canada
(Thuya plicata^ Cupressus Nootkatensis^Picea Sitchensis, Pseudotsuga and
Sequoia)* do not appear able to compete without assistance with the much-
enduring strays of the British Flora. The intense vitality of many of the
plants of the British Flora, on introduction to distant colonies, is a matter of
general remark ; and older, more isolated Floras (Australia, California,
Oceanic Islands) are rapidly devastated by the introduction of the weeds of
cultivation.3 These are not so much the plants of the wild woodland flora
indigenous to Great Britain, as * human associates ' similarly introduced into
this country from the entire continent of Europe and Western Asia, consti-
tuting the most familiar weeds of cultivation, and so maintained in human
association over many thousand years. Little reliance can be placed on
alleged cases of such plants being found * truly wild ' in any district once
inhabited by man. Wherever man goes, he picks up a few more such
associates, which follow his cleared ground in enormous profusion : where
he can live, they can flourish, and by such unconscious assistance, oppor-
tunity may be given for the survival under these new conditions of new
races of mutants, some of which may thus appear to gain additional strength,
rendering them ' invasive ' where previously they were held in check.
British peoples, as essentially corn-associates, unconsciously select any plants
which follow the same periodicity as that of the wheat-crop ; and such
plants in mass-cultivation, as weeds of a cultivated crop, admit a seed-output
which may cover a wastage far in advance of that of local forms just holding
their own under conditions of extreme competition. In a formation which
has attained a certain degree of equilibrium, and is so far ' closed ', the
introduction of seeds of wholly new plants will be a disturbing factor,
affecting the wastage of previous occupants. Only by direct experiment
does one realize the amount of seed required to produce a few specimens of
some admitted ' alien ' in open competition with a cultivated crop ; let alone
to establish it in a closed woodland or pasture- formation.4

As previously indicated, human occupation of the Oxford district is traced
back at least to the Wolvercote sandbank of the Third Terrace, at 250 ft.
elevation. The flats of Port Meadow, at 190 ft., indicate some 60 ft. of eroded
valley; a process which may have taken 50,000-100,000 years. Palaeolithic

1 Journal of Botany (1921), p. 354, Colonization of Snowdon.

8 Sequoia sempervirens (Redwood) is narrowly restricted to the sea-fog zone of the Pacific
Slope, and other trees in less degree.

3 Sinclair (1885), Indigenous Flowers of the Hawaiian Islands, Introduction: 'Forest-fires,
animals, and agriculture, have so changed the islands, within the last fifty or sixty years, that one
can now travel for miles, in some districts, without finding a single indigenous plant : the ground
being wholly taken possession of by weeds, shrubs, and grasses, imported from various countries.'

Hooker recorded the last plant * farthest South ', as a specimen of Capsella Bttrsa-pastoris , growing
at the door of a deserted sealer's hut. For the Dandelion in British Columbia, cf. Journal of
Botany, 1922, p. 274: also Thomson, 1922, Naturalization of Plants and Animals in New Zealand.

4 An arable field adjacent to Bagley Wood, with an aggregate flora of 102 species (including
the boundary hedges), gave 73 forms on ground prepared by steam-plough for the wheat-crop. Of
these, some 50 were undoubted aliens of the nature of human associates, or assisted types of the
indigenous flora whose status is still doubtful. Although only separated from a woodland-clearing
by an open gate-space and cart-track, but half a dozen of these last were found inside the wood, as
feeble strays for a distance of 20-30 yds.

98 Plant-life of the Oxford District

man was solely dependent on the natural products of the district ; and life is
not possible in such a North Temperate climate without the essentials of fire
and a knife. A fire can be built of twigs and branches snapped by hand, but
wattle-huts and basket-work required knives in the form of flaked flints from
the Chalk. With these it was possible to cut willows for wattle and basket-work,
as well as staves and weapon-handles. The two-edged flint-scraper is the
homologue of the safety-razor blade of to-day, thrown away when the edge was
gone. Such flaked flints, generally distributed in the Wolvercote Brick-earth,
probably indicate an encampment with woodwork done on the spot. The
Willow was the first associate of man, and to Palaeolithic man was undoubtedly
the essential tree, only replaced in later times by the Oak, following the evolution
of the iron axe.

Hazel-nuts and Blackberries in their season are the only natural food-
products of the district ; and thus Rubus, Corylus, and SaKx become the first
human associates, to an extent that suggests that some at least of the numerous
forms of native Willow are ' alien ', and that the great variety of * indigenous '
'species' of Willow owes its origin to the introduction of new types with advancing
waves of human immigration.1

To Neolithic man, still unable to cut up a big tree, other than by splitting
it with flint wedges — though log-canoes can be dug out by fire, or a tree
carefully felled by fire (as by the Maoris in 6 weeks) 2 — the Willow remained
the all-important tree for wattle and basket-work, passing on to the coppice-
shoots of the Hazel. Sparganium 3 ramosum of the swamp-area, gave the first

1 The story of the poet Pope raising the first English Weeping Willow from a basket brought
from Spain is possibly apocryphal ; but any old crate of green withy stranded on a mud-bank will
shoot and may take root. The first British Willows were the minute S. polaris and S. herbacea of
cold climate, probably followed by the earliest Spring-flowering forms, S. caprea, with associated
S. cinerea, and the bush S. aurita. The later May-flowering S. alba, S. fragilis, S. triandra,
S. pHrpurea, as well as the economic S. viminalis (Osier) are naturalized aliens of long standing.
It is interesting to note S. triandra flowering in August on the leafy shoots of the current year.

Such mingled forms may conceivably occasionally intercross and set seed ; but the seedling
history is still largely unknown. Cf. the valuable ' Cricket Bat Willow ', S. coerulea, only grown as
a carpellary plant. Elwes and Henry (1913), p. 1763.

It is also interesting to recall the thousands of years during which the Blackberry has been
dispersed by human agency over a small district, far more effectively than by the birds for whom the
fruits were originally intended ; again indefinitely assisting the propagation of mutants and possible
hybrids of the many hypothetical ' species' of the modern batidologist.

2 The Maoris of New Zealand, persisting to recent times as a race of Neolithic civilization with
no wild or domesticated cattle, and with no knowledge of any metal, yet physically and intellectually
as capable as an ordinary Englishman, affords a clear idea of the possibilities of Neolithic man in
prehistoric times. The Maori utilized every natural product of the country to the utmost. A great
Totara tree, felled by fire, would give a canoe to the maximum length of 120 ft., and with such
vessels they successfully navigated the Pacific for 5,000 miles, and made land-fall without a compass.

There is little need to postulate land-connexion of Great Britain with the continent : the land
was practically covered with forest ; sea, and the river leading from the sea, formed the natural highway.
The river was the general means of getting about locally until the time of the Normans. A camp on
the Third Terrace at Wolvercote, or on Wytham Hill, would have had the same value as mi^ht the
Castle Mound in the time of the Danes. A dug-out canoe, found under peat at Brigg (Lincolnshire,
1884), was made from a log of Oak, 48^ ft. long and 6ft. diameter, without the use of any metal;
a finer tree than any standing at the present day (cf. Elwes and Henry, 1907, p. 343).

3 Sparganium leaves, cut and allowed to dry, but not to become brittle, make material almost
as good for tying as Bast, or Raffia of to-day, and were so used to recent times. They are still
employed for rush-mats and baskets. For local industries by cottagers and gipsies, continuing most
ancient practice, cf. Woods (1921), Rural Industries round Oxford : for hazel wattle-hurdles, rakes,
brooms, split-willow hurdles, and split willow for basket-work (p. 94). Glyceria aquatica of the
river, cut and used for thatching hay-ricks instead of straw, has been noted (1922).

Traces of older Neolithic practices still remain : 'wattle and daub' for huts, of the hazel and
willow of the woodland, with abundant Oxford and Kimeridge Clays, is replaced by ' lath and
plaster' ; the lath of cheap imported Pinus sylvestris, and the clays and limestones burnt for bricks
and mortar. River-gravels beaten into the daub gave a weather-proof face, and gravel with cement is
still seen on modern villa-residences. Turves, as originally cut for roofing-purposes (Plot), are now
devoted to making lawns; but the burnt tile, or the cut slab of Stonesfield Slate, maintains the
original shape. Local terrace-gravels afford an ideal material for garden-paths, as rough blocks of
Coral Rag which may be dug out of the ground, as well as quarried, make excellent rockeries for
calcicolous plants. Though deficient in 'good building-stone, the district carries a wide range of
clays, sands, gravels, and in former times peat.

12. Ferry Hinksey Stream, Aug. 1921. Pollard willow, Sagittaria, $c.

13. Old River, Medley, July 1921. Limnanthemum, Oenanthe
fluviatilis, Nuphar, Srirpus lacustris, $c.

Aliens and Adventives 99

textile, as ropes for tying (only replaced by the introduction of TiUa, as the
' Line-tree ' for Bast-ropes giving efficient haulage material). The flexible
stout basal shoots of the Hazel afforded the first bows; as the slender
beautifully straight first year's shoots were the only local material from which
an arrow could be trimmed with little difficulty by a flint-knife. There was
still no sharper edge than a flaked flint : oyster-shells from the coast, or mussel-
shells from the river, are only efficient for minor purposes. Ash might give
a tougher shaft for tools and weapons, but required more trimming, as
pollarded Yew ultimately replaced other staves for bows. The introduction
of domesticated cattle brought with them pasture-grasses, and the weeds of
waste-heaps from Central Europe. The addition of food-g;rains implies all the
weeds of the corn-fields of Europe, due to imperfectly winnowed seed. No
boat could come from Spain without bringing Chestnuts as common food, and
ships from the Mediterranean probably brought a greater variety of plants than
came by land ; e. g., ship-transport of cattle implies some sort of hay or fodder
with its seeds and weeds ; the mild winter climate of S. England encourages
the plants of S. Europe, which may fail in a more ' continental' winter of
N. Germany. Only climatic conditions would prevent the establishment of seeds
of the Date and Fig.

To this period may be probably referred the first introduction of the weeds
of waste and foul ground around dwellings, as the establishment of many
Chenopods, Polygonums, and Docks, which pass as indigenous, and are similarly
associated with man on the main continent of Europe. The Sting Nettle
(Urtica dtoica], probably indigenous, as one of the last herbaceous repre-
sentatives farthest north of a distinctly tropical family, has always been one of
these assisted associates, primitively utilized as a textile, before the introduction
of Hemp (oriental) and Flax (N. African).

In later millennia, as indicated by the culture of the early British before the
time of Julius Caesar, extensive connexion with the East, either by overland
migration, or by means of navigation from the Mediterranean, is shown in
economic plants of the time ; though the connexion of the South Coast with
the Midlands may have been but slight. The cultivation of forms of Wheat,
the use of Woad (Isatis), and the cult of the Mistletoe — which as Viscum album
replaces the Loranthus europaeus of the Evergreen Oaks (Quercus Ilex) of
Thessaly — may preserve evidence of overland migrations to the North and
West, as does the gradual dissemination of the use of bronze as a special type
of alloy, and the use of horses. On the other hand, the Flax-plant of Egypt
and N. Africa, as also the Saffron Crocus of the Eastern Mediterranean, may
indicate commerce by sea. The cornfields of cereals from Western Asia still
harbour the weeds of N. Africa ; and the majority of ' naturalized ' weeds,
still unable to make good in woodland, were undoubtedly well-established long
before the historical epoch. More efficient tools led to the introduction of
soft-wooded trees, Salix alba, Populus m'gra, and possibly Tilia and the
Sycamore, as more easily worked.

The four centuries of the Roman occupation, with their increasing civiliza-
tion, saw the Common Elm, Sycamore, Lime and Poplar well-established as
timber-trees ; and undoubtedly all the economic plants of S. Europe that would
grow at all were in general cultivation. With seed-corn and hay from Gaul,
Italy, and N. Africa, came further weeds of cultivation ; and with the families
of officials and soldiers retired on the land, garden-flowers, herbs, and vegetables
of S. Europe and the East; a few of which may still survive as naturalized
in the South, or as strays in the vicinity of Roman centres, in virtue of their
successful perennation-stages. This applies more particularly to the decorative
flowers of early spring (Snowdrops and the early Crocus of the Eastern
Mediterranean, Leucojum vernum, L. aestivum, and all Narcissi beyond the
common Daffodil): the Box (Buxus), utilized for its timber, and medicinal
plants of established classical value, as described in Dioscorides (Paeom'a,
Helleborus, Aconiium), as also the ' Glastonbury Thorn '. Economic plants as
Vitis, Ficus, and Onions were undoubtedly grown, but would soon die out

ioo Plant-life of the Oxford District

(as individuals are incapable of propagation without assistance) when the
connexion with Roman Gaul and Spain was broken at the English conquest.

Early English seeking land capable of growing corn, brought seed-corn
from N. Germany, with associated weeds, as also fodder and hay of some sort
with their cattle, with the probability of introducing any weeds of North Europe
not previously imported from the South. As the forests were progressively
cleared, the more useful trees as Willows and Poplars were increasingly
planted, since these grow freely by the sides of streams and ditches from large
sets and even poles, with no necessary knowledge of seedlings. Hazel-coppice,
as longest surviving underwood, remained invaluable for nuts and wattle, and
Oak as the longest-living standard tree became the timber of building-construc-
tions ; the oak-wood also valuable for acorns feeding hogs. Intercourse with
Rome was resumed by the agency of the Church ; the economic plants of
S. Europe being continually re-introduced by patriotic pilgrims, and distributed
from monastery gardens ; as were also decorative or attractive and scented
flowers (cf. Hollyhock, Myrtle, Laurel (Laurus nobilis), Lavender, Rosemary
andfasminum officinale), together with medicinal plants (as Aristolochia Clematitis
surviving at Godstow Nunnery). Records of cultivation, somewhere in Britain,
have little bearing on strictly local conditions ; and many such plants may have
been introduced independently at different times, and allowed to die out, as
in the manner of present times, when the novelty is worn off. Vines have been
grown in vineyards, but have been replaced by apple-orchards. Figs were
always attractive, as also Mulberries, and old plants are still growing at Oxford
as attempts at introduction.1

Definite record in Botanical Literature begins with Turner,2 and more
particularly Gerard3 for the London District (1596). The latter shows a general
knowledge of the plants of Europe in cultivation, and also several from North
America (cf. Helianthus annuus] ; an attempt at the acclimatization of every-
thing that could be grown in the open being made, as the expression of a
growing scientific interest in new plants for their own sakes, rather than for
their ' vertues '. The general dated list for introductions from this time onward
is found in Aiton (i8i4),4 though plants marked 1548 may have been cultivated
for an indefinite period.

Special interest centres in the few vigorous types which have succeeded
in making more recent impression on the local flora, and may be so far
regarded as invasive : —

Elodea canadensis (N. America, 1842), in ditches, streams and river:

Crepis taraxadfolia (S. Europe), of grass-fields, spreading to waste places and

good ground :
Veronica Tournefortii (SE. Europe, 1829), of arable fields, extending to roadsides

and gardens :

Senecio squalidus (Medit. Region), in all waste ground, allotments and walls :
Geranium pyrenaicum (SW. Europe, 1762), in hedgerows and fields near houses:
Symphoricarpus racemosus (N. America, 1818), planted in hedges, and long-
enduring :

as also the various trees in forest-cultivation, and the common and more
conspicuous shrubs of gardens, parks, and hedgerows, as planted at some
time, and now maintained as assisted associates of man, whether for economic
or aesthetic purposes. Many such forms are now common objects of the
district, as familiar as most of the forms of the indigenous flora, if not more
so, and every one is expected to know something of them.

1 Cf. The 'Pocock Fig', Christ Church, 1636: Gunther, Oxford Gardens, 1912, p. 207 : The
Wild Fig (Ficus Carted} vtas germinated as a curiosity from Smyrna figs in the Botanic Garden, and
bore its first crop of ' Profichi ', 1910. The Merton College Mulberry (Morus nigra) may date from
1605.

2 Turner (1551), Herball ; ist edit. 1548.

3 Gerard (1597), Herball; catalogue of the garden, 1596.

4 Aiton (1814), Epitome of the Second Edition of the Horlus Kewensis (Linnaean System).

Aliens and Adventwes 101

By the Romans, if not before, were introduced the Sweet Chestnut
(Castanea saliva) for nuts and clean-growing timber which splits even better
than Oak, Ulmus campcstris, probably from Spain, for timber, Sycamore,
Lime and Poplar (P. nigra and possibly P. canescens, as soft timber, light and
not splintering, hence used for carts) ; also larger Willows (Salix alba, and
probably S. fragilis, the Withy) as adapted for growing by the water-side,
as also Osiers and associated forms for basket-work. Other trees of the
Mediterranean region, and often Sycamore, Lime, Chestnut, will die out if not
planted again; but Willows and Poplars are readily propagated by the most
ignorant without any knowledge of seed-regeneration by putting in stakes (sets).
Common Elm and Populus canescens are practically indestructible owing to
active production of suckers.1

Before the printed records of the Sixteenth Century (1548) plants of
S. Europe were grown as trees, food-plants and flowers, as the Cypress
(Cupressus sempervirens), Pinus Pinea, Plane. Pink Almond and Cherry, Spruce,
and Jasminum officinale. Myrtle and Daphne.

Sixteenth-century records include Laurustinus (Viburnum Tinus), Lilac
(Syringa vulgaris), Laburnum, Bay-Tree (Laurus nobilis\ Colutea arbor escens
(Bladder Senna), Walnut {Juglans regid), Quince (Cydonia vulgaris\ Evergreen
Oak (Qttercus Ilex)] and Yucca gloriosa from America with Thuya occidentals
(Arbor Vitae), also Pinus Pinaster.

The Seventeenth Century adds Cedrus Libam (1683) ; European trees as
Abies pectinata (1603), Larix (1629), Acer platanoides (1683); North American
trees, Liriodendron tulipifera (1663), Robinia Pseudacacia (1640), with Rhus
typhina (Sumach, 1629) and Ampelopsis hederacea (Virginian Creeper, 1629):
Evergreens from the Mediterranean, Prunus Laurocerasus (Cherry Laurel,
1629), Prunus lusitanica (Portugal Laurel, 1648), with garden shrubs, Lycium
barbarum (1696) and Crataegus Pyracantha (1629). Most striking of all the
Horsechestnut (Aesculus Hippocastanum, from the Caucasus, 1629).

The Eighteenth Century does little more than continue the same series
of decorative trees and shrubs for garden purposes, with a few of economic
significance : —

Populus pyramidalis (1758), Populus serotina (1787), Pinus Strobus
(Weymouth Pine) 1705, Araucaria imbricata (Monkey Puzzle) 1796, Ailanthus
glandulosa (1751), Magnolia grandiflora (1737), M. conspicua (1789), Buddleia
globosa (1774), Aucuba japonica (17835, 0*1876). Chimonanthus fragrans
(1776), Sophor a japonica (1753), Tsuga canadensis (1736).

The Nineteenth Century, especially in the latter half, has seen the great
influx of garden-shrubs of decorative value, as small gardens of the middle-class
population become enormously more important and numerous than the large
estates of the eighteenth century. While the great majority of older introduc-
tions are so well-established as to receive popular names, this does not apply to
the more recent additions. The century also marks a great increase in
Conifers, as evergreen trees and shrubs, more particularly from Japan and the
Pacific Slope of N. America, many of which are hoped to improve forest-
cultivation. But with the addition of so many new forms, a certain amount
of selection is unavoidable ; older favourites are voted ' old-fashioned ', and tend
to be neglected for novelties which are not always an improvement. Among the
more familiar shrubs of suburban gardens, cf. : —

Ampelopsis Veitchii (Hort.), Japan, 1868.
Berberis Aquifolium, N. America, 1823.
Berberis Darwinii, S. Chili, 1849.
Buddleia variabilis (vars.) China, 1896.
Ceanothus azureus, Mexico, 1818.

1 Populus cantscens will send up suckers 50 yds. Jrom the parent tree ; its seedling history
appears unknown. Populus nigra stands pollarding, but is now an uncommon tree, having been
replaced in ecological station by the mutant Lombardy Poplar (P. fastigiata), and the hybrid
P. serotina (Black Italian Poplar), the finest tree locally. (Elwes and Henry, 1913, p. 1803.).

IO2 PI ant- life of the Oxford District

•

Ceanolhus Veitchianus, California, 1859.

Choisya ternata, Mexico. 1825.

Clematis Jackmanni (hybrids) 1862.

Cotoneaster Simonsii, India, 1869.

Cydoniajaponica, Japan, 1815.

Euonymus japonicus, Japan, 1804.

Fuchsia macrostema, hybrid Riccartoni^ 1830.

Jasminum nudiflorum, China, 1844.

Leycesteriaformosa.) Himalya, 1824.

Ligustrum japonicum, Japan, 1845.

Oharia Haastii, New Zealand, 1858.

Prunus Pissardi, Persia, 1881.

Prunus cerasifera, 1864, Myrobolan Plum, S. Europe.

Ribes sanguineum, NW. America, 1826.

Spiraea ariae/olia, N W.America, 1830.

Spiraea Lindleyana, Himalya, 1845.

Siaphylea colchica, Caucasus, 1879.

Symphoricarpus racemosus, N. America, 1818.

Veronica Tr aver sit, New Zealand, 1873.

Wistaria sinensts, China, 1816.

Also as forest-trees, largely grown as garden shrubs and park-specimens,
all evergreen : —

A fries nobilis, Oregon, 1831.

Cedrus Deodar a, Himalya, 1831.

Chamaecyparis Lawsoniana, California, 1853.

Chamaecyparis Nootkatensis, British Columbia, 1850.

Cupressus macrocarpa, Monterey, 1838.

Pimis austriaca, Austria, 1835.

Pinus insignis, Monterey, 1833.

Pinus excelsa, Himalya, 1827.

Pseudotsuga Douglasii, California, 1827.

Sequoia sempervirens, California, 1 846.

Sequoia gigantea, California, 1853.

Thuya (Biota) orientalis, Japan, 1860.

Thujya gigantea, NW. America, 1853.

The case of the introduced aliens of garden-cultivation, as herbaceous
perennials and annuals, requires separate consideration : that of the alien
tree and shrub is more significant as affecting the general appearance of the
landscape and roadsides. As contrasted with the present abundance of
introduced trees, flowering shrubs, and evergreen Conifers, the poverty of
the older flora is pathetically illustrated by the early English practice
of planting evergreens around the Churches, to give some appearance of life
and greenery during the six long winter months — Yew and Ivy being the
only available plants, with Holly for Christmas decoration, and the ' Palm '
(Salix caprea o*) at Easter. Yet neither Yew nor Holly is now found
growing locally except where planted.

The same people who did this would show the greatest avidity in
obtaining other plants from the Continent and South Europe, to ameliorate
the wretched outlook of the clay countryside in cold, wet, and dark winter.
Older English literature testifies to the affection felt for the early Primrose,
Violets, Cowslip, Pansy, and Cuckoo-Flowers, as well as the ubiquitous
Buttercups, Daisies, and Dandelions of the pastures, and the Blackthorn,
Hawthorn, Crab Apple, and Elder of the Waste.

The poverty of the local aboriginal flora may be visualized by abstract-
ing from the present landscape all the Common Elms, Huntingdon Elms
Lombardy Poplars, Black Italian Poplars, the pollarded Willows, the Limes

fl

§1

:

r

PQ

Aliens and Adventives 103

and Planes of the streets, all Conifers, Austrian Pine, Scots Pine, Larch,
Spruce, Cypress and Thuya of woodland and parkland, Sycamore, Horse
Chestnut, Walnut, Sweet Chestnut, and probably Beech and Hornbeam.

The alien herbaceous flora includes the great majority of all the plants of
occupied ground to the extent of 86 per cent, of the county area, and is respon-
sible for many pasture-grasses and weeds, as well as the associates of arable
land, to a general estimate of nearly half the ecological flora. A few of
these are of special local interest, as so familiar and long-established that
they commonly pass as indigenous. Thus, Fritillaria Meleagris is well-
established in the wholly artificial alluvial pastures, and not elsewhere ;
though badly treated and picked on sight : Acorus Calamus (Sweet Flag) of
the river holds its own on the edge of the bank by vegetative growth, but
never fruits.

English gardens,1 instead of being filled with simples and a few decora-
tive flowers, become the repositories of exotic forms from all parts of the
world, their mutants, hybrids, and teratological phenomena, more particularly
in the form of ' Florists' flowers ',2 as the apotheosis of the alien, assisted and
selected by man, in a wholly artificial and arbitrary manner, not invariably
directed by the best taste, perception of form, or colour-sense, and usually
entirely ignoring the meaning, function, and evolution of the floral and
reproductive mechanism. Before these the indigenous flora shrinks as an
assemblage of weeds, on no account to be tolerated inside the garden-walls,
except in the form of turf. Where the last interest of such forms centres in
the manner in which they may be Mendelized, or inter-crossed to give still
more puzzling freaks, one may still turn with relief to the honest free-
fighters of the wild, knowing the great strength such plants have in reserve,
and the rapid and devastating manner in which they would return once the
hand of man were relaxed. The best gardens are only measured in hundreds
of years, the wild flora in hundreds of thousands, the scope of Modern
Botany takes into account many hundreds of millions.

1 Amherst (1895), Gardening 'n England, pp. 59, 123.

Parkinson (1629), Paradisus Terrestris: The Garden of Pleasant Flowers.
Besler (1613), Hortus F^ystettensis.

2 Nicholson, Dictionary of Gardening, 'Florists' Flowers'.

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