ABSTRACT. Dot maps are provided to depict the distribution
at the county level of the pteridophytes (Lycopodiophyta, Equisetophyta,
Polypodiophyta) and gymnosperms (Coniferophyta) growing outside
of cultivation in the six New England states of the northeastern
United States. The 174 taxa (species, subspecies, varieties and
hybrids, but not forms) are mapped at the county level based on
specimens in the major herbaria of Maine, New Hampshire, Vermont,
Massachusetts, Rhode Island and Connecticut, with primary emphasis
on the holdings of the New England Botanical Club Herbarium (NEBC).
Brief synonymy to account for names used in recent manuals and
floras for the area, habitat and chromosome information and common
names also are provided.
Key words: Flora, New England, atlas, distribution,
This article is the first in a series that will
present the distributions of the vascular flora of New England
in the form of dot distribution maps at the county level. New
England comprises the six northeastern states of the United States:
Maine, New Hampshire, Vermont, Massachusetts, Rhode Island and
Connecticut. These states range in latitude from 41°N to
47°28'N and in longitude from 67°W to 73°45'W.
The elevation of the region extends from sea level to 1,898 m
(6,228 ft) at the summit of Mt. Washington, New Hampshire, the
highest mountain in eastern North America outside of North Carolina.
The total area of the region is 172,515 km2 (66,608
miles2) including bodies of water; the total land area
is 163,157 km2 (62,995 miles2). The effects
of continental glaciers, which covered the entire region several
times during the Pleistocene, and the last of which did not retreat
until about 15,000 years ago, are still clearly evident throughout
the area. The state by state statistics on size and elevation
are shown in Table 1 (Merriam-Webster, Inc. 1984).
The more southerly states of Massachusetts, Rhode Island, and
Connecticut are densely populated (the least densely populated
of these three states, Connecticut, had an average of 262 persons
per km2 in 1990; Hoffman 1992). The northern states
of Maine, New Hampshire, and Vermont are mostly rural (the most
densely populated of these three states, New Hampshire, had an
average of 48 persons per km2 in 1990; Hoffman 1992).
This work encompasses all vascular plants (pteridophytes and
spermatophytes) at the rank of species, subspecies, and variety
growing outside of cultivation in the New England states. Hybrids
also will be included, but forms and other ranks below the level
of variety will not. The dots are based primarily on voucher
specimens in the herbaria of New England representing reproducing
populations, or plants persisting after cultivation when it is
uncertain that they are actually naturalized. This first installment
includes the pteridophytes (Lycopodiophyta, Equisetophyta, Polypodiophyta)
and gymnosperms (Coniferophyta). Future accounts will treat the
distribution of angiosperms.
We intend to gather this series of articles, together with additional
background material, into a separate volume upon completion of
all the maps, and to make it available on the Internet as
various parts are finished. It is our hope that, in the meantime,
these articles will stimulate additional field work to supplement
the distributions portrayed in the maps. The New England Botanical
Club herbarium, which has proven to be the most important resource
for this project, is especially eager to receive specimens documenting
range extensions. We also would like to be informed of such specimens
in other herbaria. Similarly, because the atlas of the New England
flora will be updated continuously as new information becomes
available, we are eager to receive notification of published corrections
of cytological information and new, documented chromosome counts
for taxa in the New England flora.
This atlas grew out of an inventory of the New England Botanical
Club vascular plant herbarium. The purpose of the inventory,
conducted at the county level, was to serve as a filter for the
processing of a large number of unmounted specimens being considered
for accession. Consequently, the core of the database for this
atlas consists of specimens in the herbarium of vascular plants
of the New England Botanical Club (NEBC). The NEBC herbarium,
which limits its geographical scope to the New England states,
presently comprises more than 253,000 specimens and is the largest
collection of plants for the New England region.
In the mid 1980s the herbarium inventory was expanded into an
atlas project, since data from the NEBC herbarium essentially
depict the distributions of the vascular plants of New England.
Additional data from specimens in other major herbaria with large
holdings of New England plants have allowed us to portray the
distributions more completely.
The data represented currently by specimens in New England herbaria
best depict vascular plant distributions when displayed at the
county level. Attempting to display such data by the exact geographical
coordinates of each collection locality, or even at the township
level, distorts the actual distributions. By such detailed mapping,
patterns tend to reflect concentrated collecting along major highways
and clustering near popular resort areas or botanical hot spots.
This was evident from some of the detailed distribution maps
produced about 15 years ago by the plant distribution committee
(now defunct) of the New England Botanical Club. The distortions
portrayed by such detailed mapping are resolved by using data
only at the county level.
The counties of New England range in size from Bristol County,
Rhode Island (65 km2, or 25 mi.2), to Aroostook
County, Maine (17,666 km2, or 6,821 mi.2
- land only). The great majority of counties, however, are between
1,300 km2 (500 mi.2) and 3900 km2
(1,500 mi.2). To reduce the size disparity at the
large end, and to depict distributions more evenly, the largest
Maine counties are subdivided. Penobscot, Piscataquis, Somerset,
and Oxford counties are divided arbitrarily into roughly equal-sized,
north and south sectors along township boundaries. Aroostook County,
the largest county, is divided into three sectors. Coös
County, New Hampshire, is divided into north and south sectors.
The division of Coös County isolates the White Mountains,
which harbor an alpine flora associated mostly with New England's
highest peak, Mount Washington. Figure 1
shows the location of states and counties of New England and the
subdivisions of the largest counties.
Data were collected primarily from herbarium specimens of major
herbaria in New England. The herbaria used to compile data for
this work were those of the New England Botanical Club
(A, AMES, GH),
University of Maine (MAINE),
University of Massachusetts
University of New Hampshire (NHA),
University of Rhode Island
University of Vermont (VT)
and Brown University (BRU).
Records from the herbaria at
the University of Connecticut
Connecticut Botanical Society
(NCBS), and Yale University
(YU) were accessed from data
compiled by Leslie Mehrhoff. Lastly, the notebooks of Harry Ahles at the
University of Massachusetts were consulted. Ahles visited these
same herbaria, plus one or two others, in the 1960s and 1970s
to gather locality information at the county level. We obtained
some records from systematic treatments where the information
on voucher specimens was specific enough to provide county data
and the name of the herbarium where the specimens were deposited.
In recording the collection data no attempt was made to verify
the accuracy of the identification of every specimen, but obvious
misidentifications were annotated with corrections. Even though
the basis for a particular dot might be a misidentified specimen,
for plants common within New England, our view is that the taxon
most likely occurs within the county. Specimens documenting disjunct
or marginal occurrences (or otherwise rare, endangered or threatened
taxa) usually have received greater scrutiny, because of a heightened
interest in rare plants nationwide, and are less likely to be
The data were entered into a simple computer database using one
of several letters in the county field as a code to indicate the
herbarium in which the voucher specimen is deposited. The letter
code indicates the first herbarium where a voucher specimen was
seen. No letter codes were added for subsequent voucher specimens
at other herbaria, because our primary objective has been to plot
the distribution of the taxon, not to inventory the holdings of
any particular herbarium. While such information might be of
value for some purposes, we felt that our time at other herbaria
was best devoted to searching for data not found in the New England
Botanical Club herbarium, or in each subsequently searched herbarium,
to fill in gaps in distribution.
The data in the database were converted to dot distribution maps
using a method devised by Angelo (1994).
The taxonomy and nomenclature adopted for this work essentially
Flora of North
America (Flora of North America
Editorial Committee 1993). With the exception of the arrangement
for the major divisions within the pteridophytes (Lycopodiophyta,
Equisetophyta and Polypodiophyta), which follows the Flora
of North America (Flora of North America Editorial Committee
1993) sequence, the families are ordered alphabetically.
The genera are alphabetical within families, as are species within
genera. Named and unnamed hybrid taxa are placed alphabetically
at the end of the genus. Unnamed hybrids combine the names of
the parents alphabetically by epithet.
Species deemed to be introduced, that is, not native in New England
at the time of European contact with North America, are indicated
by the use of all upper case type for the scientific name. No
single source of information was used in determining introduced
species. For most taxa there is little dispute as to nativity.
Where differences of opinion exist in the literature, we have
used our own judgment based on the evidence available.
A common name is supplied when it appears to be a name in general
use. Names used in New England have been given preference.
Cited chromosome numbers are taken from indices prepared by Cave
(1958a, !958b, 1959a, 1959b, 1960, 1961, 1962, 1963, 1964, 1965),
Goldblatt (1981, 1984, 1985, 1988, ), Goldblatt and Johnson (1990,
1991, 1994), Moore (1973, 1974, 1977), Ornduff (1967, 1968, 1969),
and reports by Takamiya and Kurita (1983), Taylor (1970), Tryon
(1978), Tryon and Tryon (1982), and Wagner (1971). Very few of
the counts are based on material from New England, but instead
reflect counts made from throughout the range of the taxon.
The habitat data are distillations from a variety of sources
augmented by our own field observations. An attempt was made
to indicate habitat information as it applies to a particular
taxon in New England rather than to the entire range of the taxon.
Synonymy is provided primarily with respect to names used in
the standard manuals covering New England published from 1950
onward, including Fernald (1950), Gleason (1952), Gleason and
Cronquist (1963, 1991), and Seymour (1969a, 1982).
A selection of references, including many not cited above, is
provided. This list consists of the standard manuals published
from 1950 to date, regional and county floras and checklists produced
after 1950, and what we believe to be the key articles and books
on the pteridophytes and gymnosperms pertinent to New England.
We would appreciate being notified of papers we may have overlooked.
ACKNOWLEDGMENTS. We thank the curators and directors of the herbaria
of Brown University, Harvard University, the University of Maine,
University of Massachusetts, the University of New Hampshire,
the University of Rhode Island, and the University of Vermont
for allowing us access to their collections. We particularly
appreciate the kindness of David Barrington, Chris Campbell and
Karen Searcy for allowing use of the collections in their care
outside of normal hours of operation. We are grateful also to
Karen Searcy for allowing access to the notebooks of Harry E.
Ahles at the University of Massachusetts. Leslie J. Mehrhoff
was very generous in sharing data on pteridophytes and gymnosperms
that he has collected from the herbaria at the University of Connecticut
and Yale University. James Hinds assisted by checking the University
of Maine herbarium for some discrepancies in the Harry Ahles data.
Thomas Vining, at the University of Maine, checked additional
specimen data for us at that institution. David Barrington, David
S. Conant, and James Hickey made many helpful comments on various
versions of the manuscript and Warren H. "Herb" Wagner
was particularly helpful and encouraging. We thank Bruce
A. Sorrie for collecting data from the Harvard University herbaria
in the early stages of this project. Lastly we thank Arthur Haines for
providing updates after the print publication of this atlas.