Flora of the vicinity of New York

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FLORA OF THE VICINITY OF NEW YORK

By NORMAN TAYLOR

Reprinted from The Scientific Monthly, June, 1917
Copyright, 1916, BY THE SCIENCE PRESS

[Eepriuted from The Scientific Monthly, June, 1917.]

FLORA OP THE VICINITY OF NEW YOEK

Bx NORMAN TAYLOR

BKOOKLYN BOTANIC GAEDEN

rTN 1749-1751 Cadwallader Golden, lieutenant-governor of New York
-J- and correspondent of Linnaeus, published the first flora of New
York and vicinit)'. It was a list of the plants as observed by himself
and his daughter Jane Golden, growing near their home in what is still
called "Goldenham," Orange Co. Written by a man who wrote to
Gronovius that "botany is an amusement which may be made greater
to the Ladies who are often at a loss to fill up their time," it well
reflects the attitude of his period. As a historical record the list is
valuable. As a forecast of the modern position of botany or women,
his remarks are commended to botanists and to those feminists who find
it difficult to "fill up their time."

Not until 1819 was there another list of this importance, when
John Torrey published his "Catalogue of Plants growing Spontane-
ously within thirty miles of the City of New York." This was a book
of 102 pages and listed hundreds of species and varieties, some of which
are now rare or extinct near the city. To touch only the high spots
of a long historical record, mention should be made of Leggett's "Ee-
vised catalogue of the plants, native and naturalized, within thirty-three
miles of New York" (1870-1874) and the "Preliminary Catalogue
of Anthophyta and Pteridophyta " reported as growing spontaneously
within one hundred miles of New York City by Britton, Stearns and
Poggenburg (1888). Some of these lists contained notes on the dis-
tribution of the species, but in most cases only lists of plant names
were possible. The outstanding character of them all, as in the begin-
nings of most science, was that they were chiefly records of facts.
They were the culmination of our forefathers' study of the local flora,
arranged in orderly fashion, which at that time was all that could be

idone.

It is impossible to talk about the vegetation of New York without
knowing very definitely what are the units of that vegetation, and it
is the chief legacy of this older generation of New York botanists, that
they have handed down to us so complete and so accurate a record
of those units, as they knew them. There were, of course, hosts of
minor efforts covering the region near the city, or parts of it, about
which nothing can be said here, except that like the more important
works their object was simply to record the facts. It should not, how-
ever, be implied that these workers lacked a larger vision which should
seek to explain or correlate their patiently acquired facts. For we
find in July, 1870, a forecast of what they were striving for, when in

549 THE SCIENTIFTO MONTHLY

the Bulletin of the Torrey Botanical Club there appeared in an ac-
count of the floral regions of that area, the statement that

Any rational catalogue of our flora should distinguish what plants ar«
absent from or peculiar to each natural region and should contain such infor-
mation in reference to soil, climate, etc., as may help to elucidate the dis-
tribution.

Among purely local botanists, this was, I think, the first statement
implying causation that had appeared. Gray, Torrey and Hooker had
all written extensively of the flora of North America, and some of
them, at any rate, had written on the larger problems of the origin
and distribution of the North American flora. For the region about
New York, with its variety of conditions, there seems to have been no
opportunity until quite recently to attempt to fulfil the hope of the
writer in 1870 who is quoted above.
^^ Eecent studies of the fiora show that there are about 2,600 different
species of fiowering plants and ferns known to grow within, roughly,
100 miles of the City. Of these 85 are ferns and their allies, 23 are
\^conifers and the balance is made up of our ordinary fiowering plants.
Of the total fiora some 613 species have been introduced from outside
the area, by man or otherwise, leaving slightly more than 2,000 species
of native plants in the region within one hundred miles of the City.^

It is a matter of common observation that these plants are not
generally distributed throughout the region. In traveling from the
Catskills to Cape May, the northern and southern limits of the area
studied, we see a variety of plants found in one or the other of these
widely separated localities, but not in both of them. Many species find
their outposts of distribution near New York. Some appear to have
come from the North or South, a few from the West, others are appar-
ently endemic in the area, and this great quantity of forms, the ap-
parent chaos of it all, raises many questions. What is the real com-
position of our flora, whence derived, and above all how did it reach its
present luxuriance and beauty? The attempt to answer these ques-
tions necessitates a review of the causes that have influenced the origin
and distribution of our native flora.

For all practical purposes the agencies affecting the distribution of
our native plants may be divided into edaphic and climatic ones.
Under the first must be considered all questions of the relation of the
vegetation to the soil and available water supply ; or more simply stated
the geological factors of distribution; under the second the relation
of the fiora to climate must be the chief concern.

From the point of view of plant distribution the last geological
phenomenon is the most important, as the continental glacier the fringe
of which stretched through Long Island, Staten Island, northern New
Jersey and Pennsylvania, had a profound influence on the migration

I Mem. N. Y. Botanical Garden, 5, 1-683, 1915.

FLORA OF VICINITY OF NEW YORK 550

of the flora existing at that time. It is obvious that whatever the
effects of geological eras before the ice age may have been on the then
existing flora, this great ice sheet must have obliterated all the vegeta-
tion in the region which it covered. All the region north of the south-
em edge of the continental ice sheet must have started with vegeta-
tively a clean slate, as it were, when the ice receded. What was the edge
of the ice sheet is now marked by an irregular range of hills which
stretch from Montauk Point to northeastern Pennsylvania. These
morainal hills mark the present southerly distribution of many of our
species of plants. Over 8 per cent, of our native flora has never been
found south of these morainal hills, notably the red pine {Pinus resi-
nosa), the balsam (Abies halsamea), yellow birch (Betula lutea) and
Quercus horealis among the trees; Ribes glandulosum, the shrubby
cinquefoil (Dasiphora fruticosa), many thorns, the Rhodora and Kal-
mia glauca among the shrubs, besides scores of herbaceous plants. /

This glaciated part of the range is characterized, too, by the large
percentage of hardwood deciduous trees, and by the great number of
introduced plants that are found there. Most of our European weeds
flourish in the much-cultivated region north of the moraine. ^

The unglaciated part of the area is mostly occupied by the coastal -
plain which, on the whole, is characterized by the long sandy or gravelly
stretches that are found on southern Long Island and New Jersey.
All of the region is geologically the most recent in the area, the surface
being largely made up of Tertiary and Cretaceous deposits in New
Jersey and over-wash material from the glacier on Long Island. From
the standpoint of the botanist the chief thing of interest about the
coastal plain is the pine-barren region of New Jersey. This region is
so unusual that the ordinary traveler is at once struck with the differ-
ence between these sandy stretches of pine-tree vegetation and the
richer flora further north.

It has been shown^ that the pine-barrens occupy ahnost exclusively
the Beacon Hill formation, in New Jersey, which has been uninter-
ruptedly out of the water since upper Miocene time, and has been sev-
eral times partly, or wholly, surrounded by sea water. Because of its
continual emergence it is the oldest region in our area that can have
been continuously covered with vegetation. For the region surround-
ing the barrens was subject several times to the invasion of sea water,
and as we have seen the glaciated area, geologically much more ancient,
must have been fairly scraped clear of vegetation by the ice. In other
words, the New Jersey pine-barrens exist exclusively on the Beacon
Hill formation, an area isolated by geological processes and maintain-
ing a relict flora, which is much older in permanency of occupation
than any of the rest of the flora near New York. ^J

Ancestrally our local flora must have consisted of purely American
2 Torreya, 12, 229-242, 1912.

551 THE SCIENTIFIC MONTHLY

plants, many of which were of southern affinities. Many southern
species still reach their extreme northern outposts of distribution in
this region. Most of the southern species are found on the coastal
plain, but a few have spread north and west of it. At the present time
over 13 per cent, of our local plants reach their northern limits within
one hundred miles of the City of New York. Many other southern
plants, also, range only slightly to the north of us.

About 8 per cent, of the native vegetation, also, consists of north-
em species that reach their southern limits within the local flora area,
and many more are found to the south of us in the mountains. The
great range of hills, stretching northeast-southwest from the Berk-
shires through the Catskills and the Highlands of the Hudson in New
York, the Kittatinny in New Jersey and to the Blue Mountains of east-
ern Pennsylvania, serve literally as a broad highway down which a host
of northern species are scattered, and to the seaward of which certain
kinds have never been known to go. That other great group of species
that creeps, almost insidiously, from the south, seems perforce to have
been huddled between the mountains and the sea. The transition be-
^tween these northern and southern elements of our flora is, of course,
nothing like so sharp as the geological regions they generally occupy
would seem to indicate. Many sporadic marauders have spread from
both camps, apparently far out of their element. Sometimes these
lonely outposts survive the competition of the new environment ; that is
notably the case of the hemlock in southern New Jersey, far from its
usual rocky hillsides, and of the coast white-cedar (Chamcecyparis)
which flourishes in the coastal-plain bogs, and maintains a rather
V&plendid isolation at Greenwood Lake, in northern New Jersey. Scores
of these cases could be cited illustrating the main lines of the distribu-
tion of our flora by occasional aggressive exceptions to it. Such spo-
radic occurrences form one of the most fascinating chapters in the his-
tory of our native flora, for are they not militant outposts of a mighty
horde of conservatives? Sometimes they perish miserably as the little
twin-flower has long since done on southern Long Island, miles from
its mountain home. Of the number of such tragedies no man can even
guess, still less speculate as to their causes, but speculation could weave
about such occurrences, and they are very numerous even in such a
limited area as this, a story the significance of which has breath-taking
possibilities. For with these outcasts, whether living or dead, is bound
up a whole history of changing climates and shifting levels- of our con-
tinent— ^mighty forces which have scattered here and there mute little
relics of their sport.

The real potency of these geological forces, or historical factors of
distribution, is so great and its appeal to the imagination can be made
so alluring, that we are in danger of attributing the general complexion
of our vegetation almost solely to them. Nothing could give us such a

FLORA OF VICINITY OF NEW YORK

552

one-sided, wholly erroneous conception. Our present climate, particu-
larly temperature, seems quite certainly to be the controlling factor in
the present distribution of many of our native species. As to rainfall
and the winds, their variation seems almost negligible in so small a
region, but temperature is a much more serious matter. There seems
to be a rather well-defined temperature barrier through which some
plants have never been known to go.

For a variety of reasons that need not detain us here, the particular
criterion of temperature response that has been studied in connection
with our native flora is that of the length of the growing season. This
is determined by figuring the number of frostless days in different parts
of the area. The accompanying map illustrates the method better than
a page of explanation could do. The arbitrarily drawn black line
through the map indicates the dividing line between colder and warmer
regions of our area. It marks, with occasional exceptions, the southerly
limit in our area of many cold-country plants. North of it occur most
of our higher elevations where the mountain species are found. The
difference of three months in the growing season as between the
Catskills and Cape May is very nearly as impressive as the conspicu-
ously different vegetation of these widely separated localities.

The mental convenience of considering separately the effects of

Fig. 1. Map Illustrating the Length of the Growing Season within 100
Miles of New York, The figures represent the number of days between the last
killing frost in spring and the first of autumn. The dark line separates the warmer
from the colder parts of the area, and Indicates generally speaking a climatic barrier
through which certain of our native plants have never been known to go.

553 TEE SCIENTIFIC MONTHLY

geology and climate on the distribution of our flora must not blind us
to the fact that these agencies do not work independently. The inter-
action of these, the further complication of the personal "aggressive-
ness" of certain species, if that term can be applied to plants, and
many other minor factors, make the problem most complex. In any
particular case it may be practically impossible to say whether a given
plant exhibits response to climatic or geological factors, or to both,
least of all as to what possible combination of both. All that can be
done is to set down the facts of distribution, both with relation to
geology and to climate, and to estimate the relative proportion of the
potency of each. That such a study must spell a large measure of
failure should deter no one. For by it is acquired an outlook upon the
vegetation of an area that no preparation of lists of species can pos-
sibly confer. Upon such a conception a flora ceases to be a catalogue,
mere scaffolding for the structure that is to follow, as necessary and
as uninteresting as the telephone directory. Upon such a conception
a flora need not concern itself with the latest hair-splitting refine-
ments of the ever-present species-monger. All of these things are sub-
sidiary to the larger problems that come from what may be called a
causative study of a flora. By it each of our native plants takes on an
added interest, to many there may be attached a history that fascinates
the most unimaginative, to the whole is given a new impetus and a
broader vision, which can make of any landscape something very like
a dramatic spectacle.

Troublesome persons with a practical bent will want to know of
what use such a study of any flora can be, least of all of the region near
New York. Apart from its consideration as a great out-door experi-
ment or laboratory where all sorts of principles of distribution can be
studied at first hand, there are purely local problems that are commer-
cially important. The draining and reclamation of our great salt-
marsh areas on Long Island and in New Jersey, which is bound up with
mosquito extermination, offers an attractive field of work where such
knowledge will have a direct bearing. The profitable utilization of the
southern part of Long Island, now a dreary waste of scrub-oak and
pitch-pine, and of the pine-barrens of New Jersey, must involve the
utilization of such studies to insure a full measure of success. The
timber and crop possibilities of some parts of the area are well indi-
cated by the wild vegetation, and the vegetational history of many parts
of the region must serve as a clue to its most profitable future utiliza-
tion. Thus a study of a flora from the standpoint of its fitness for its
environment, and the intimately related study of the environment as
fitted to the existing flora, must bulk large in any rational scheme for
the agricultural or horticultural development of the region near the
city, many parts of which are still wholly undeveloped, or, worse still,
have been recklessly exploited.

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