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Flora of the Carolinas, Virginia, and Georgia
by Alan S. Weakley
The concept that floras should be "conservative"
(i.e. should take a "lumping" approach) strikes me as
dangerous. Horton (1972), for instance, states "manual treatments
in general should be conservative, leaving the fine points of distinction
among taxa, especially infraspecific ones, to the monographer."
Floras become the standard used by the great majority of users in
an area, and taxa that are "lumped" are lost to the conciousness
of all botanists other than a few specialists. Thus, two parallel
taxonomies are established, one in common use and one (based on
the best judgments of experts in the groups) not used, except by
a few, interested in (and able to) seek out the papers of specialists.
Ecological studies, species lists for parks or natural areas, rare
species surveys, and assessments of the ecological significance
of potential conservation areas are all flawed if not based on the
best current information available. Moreover, from the standpoint
of information theory and information management, a species list
using a "lumped" taxonomy has lost information; if a
"split" taxonomy has been used, the information is retained.
Even a casual perusal of the synonymy listed under the species of
nearly any substantial genus in our flora will reveal taxa that
have been variously treated as species, infraspecific taxa (variety
or subspecies), and included within another taxon. Further studies,
sometimes based on different techniques, sometimes simply by a different
taxonomist with a different taxonomic philosophy, often result in
the overturning of a previous taxonomic judgment. The basic categories
of our taxonomy still do not have generally accepted, consensus
definitions and criteria. W ith the taxonomy of our area still in
such flux, I am inclined to provisionally accept some infraspecific
taxa (or at least mention their alleged characters in the discussion
under a species) so that they are not "lost in the shuffle."
The problem of the infraspecific categories variety and subspecies
is a vexing one. A recent study of current practice in the use of
various infraspecific categories showed that the usage of variety
and subspecies was profoundly muddled, with regional traditions
as important as taxonomic philosophy in determining usage (Hamilton
& Reichard 1992). Anderson, Crum, & Buck (1990), in a recent
checklist of North American mosses, concluded "we have been
unwilling to list both subspecies and varieties because the differences
between them are not clear to us. As far as we can judge, a subspecies
and a variety are the same thing. The varietal designation has long
been used in botany, more specifically in bryology, and we see no
particular gain, at least at this stage of our knowledge, in attempting
to erect more than the single infraspecific category, variety".
Holmgren (1994) has also presented a strong argument for use of
the varietal rank. The International Code of Botanical Nomenclature
provides a strong basis for the use of “variety” as
the primary taxonomic level below species, and “subspecies”
only when an additional intervening level is desired. “4.1.
The secondary ranks of taxa in descending sequence are tribe (tribus)
between family and genus, section (sectio) and series (series) between
genus and species, and variety (varietas) and form (forma) below
species. 4.2. If a greater number of ranks of taxa is desired, the
terms for these are made by adding the prefix "sub-" to
the terms denoting the principal or secondary ranks. A plant may
thus be assigned to taxa of the following ranks (in descending sequence):
regnum, subregnum, divisio or phylum, subdivisio or subphylum, classis,
subclassis, ordo, subordo, familia, subfamilia, tribus, subtribus,
genus, subgenus, sectio, subsectio, series, subseries, species,
subspecies, varietas, subvarietas, forma, subforma” (Greuter
et al. 2000).
While I strongly agree with this sentiment, standardizing all infraspecific
taxa recognized in our area to either variety or subspecies would
involve hundreds of new combinations; such proliferation of combinations
(not based on new knowledge of the taxa) seems undesirable, though
such an approach was taken by Dorn (1988) in the considerably smaller
flora of W yoming. For now, I am primarily using variety where choices
exist, but accepting subspecies where an equivalent varietal name
does not exist. Occasionally (following recent monographers), I
have accepted subspecies as an infraspecific category indicating
a more distinctive taxon than variety. This is not a happy solution,
since it means that the categories of subspecies and variety are
not used consistently to indicate a different level of taxonomic
distinction. I have been disinclined to use quadrinomials, as, for
instance, Chamaecrista nictitans (Linnaeus) Moench ssp. nictitans
var. aspera (Muhlenberg ex Elliott) Irwin & Barneby, because
they generally strike me as unwieldy, impractical, and
unnecessarily confusing, without providing sufficient compensating
benefits (our state of knowledge rarely warranting or supporting
such finely distinguished classifications of relationships).
In general, the user or reader will find the following general differences
in taxonomic treatment, as compared to other floristic treatments
of the area, such as Radford, Ahles, & Bell (RAB), Fernald (F),
Gleason and Cronquist, 1st and 2nd editions (G, C), Small (S), Godfrey
& Wooten (GW), the treatments so far published as part of the
vascular flora of the southeastern states (SE), Kartesz (K), W offord
(W ), and Harvill et al. (H). Family level taxonomy generally follows
Cronquist's recent work (reflected in C and K), with a few groups
split more finely; this represents a generally somewhat finer splitting
than RAB, F, G, GW, W , and H, substantially coarser than S. Generic
level 5 taxonomy has for the last several decades been generally
headed towards finer divisions; this treatment reflects that trend,
with genera split somewhat more than RAB, F, G, W , and H, about
the same as C, GW, K, and SE, and more coarsely than S. It is interesting
to note, though, that our generic concepts are now perhaps more
than halfway back to Small and Rrydberg! At the species level, the
treatment is about equivalent to C, K, and SE, slightly more finely
split than F and G, substantially more finely split than RAB, GW,
H, and W, and substantially coarser than S. Infraspecific taxa are
recognized much more frequently than RAB, H, and W , somewhat more
frequently than GW, about the same as C, G, K, SE, and much less
frequently than F (probably less than half of Fernaldian varieties
are recognized at any level). S did not use varieties (except very
exceptionally); many taxa recognized by S as species are here regarded
as varieties, or not recognized at all. Overall and on average,
substantially more taxa are recognized than are by RAB and H, slightly
more than by C, G, GW, W , about the same as K and SE, and substantially
fewer than by F or S.
The Flora is being prepared as time allows. Drafts
of family and genus treatments are being made available to interested
botanists for use and field-testing. Some treatments must be considered
tentative until further testing in the field and herbarium can be
accomplished. All treatments should be considered as works in progress
at this time, likely to change slightly or greatly before publication.
For some species, determination of the distributions, habitats,
and phenology requires additional herbarium and field work, not
yet completed. I welcome suggestions on format and content.
  
Curriculum North Carolina UNC
In Ecology Botanical Garden Biology Department
University of North Carolina
Herbarium
CB# 3280, Coker Hall
University of North Carolina
Chapel Hill, NC 27599-3280
phone: (919) 962-6931
fax: (919) 962-6930
email: herbarium@bio.unc.edu
Last Updated: 4 March
2005
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