Bulletin - United States National Museum - Smithsonian Institution

34 FLORA OF WASHINGTON AND VICINITY.
IX. STATISTICAL VIEW OF THE FLORA.
In order to present a clear view of the general character of the vege-
tation of the District of Golnmbia and the adjacent country, I have
made a somewhat careful analysis of the larger groups and families, and
comparison of them not o nly with each other but with the same groups
and families in larger areas and other local floras. The general results
are presented below.
It is important to remark that in all enumerations it is not simply the
number of species as at present recognized, but the number of different
plants (species and varieties) that is employed. The reason for doing
this is, that in very many cases well-marked varieties are eventually
made species, and if two plants really differ there is little probability
that they will ever be merged into one species without that difference
being indicated by some difference of name. The aim has therefore
been to take account of the number of plants without regard, to the
manner in which they are named.
The whole number of vascular plants now known to this flora, as cat-
alogued in the list appended to this paper, is 1,249, and these belong
to 527 different genera, or about 2^ species to each genus. These are
distributed among the several systematic groups as follows:
Polypetalae .
GamopetaliB
. .
Total DicblaraydesB...
Monochlamydeai (Apetalse)
Total Dicotyledons .
Monocotyledons
Gymnospermaj (Coniferae)
Total Phanogamia..
Cryptogamia
Total Vascular Plants
Series, Classes, and Divisions.
The pevccntages of the total are as follows
Polypetalaj
Gamopetalaj
Total DichlamydeiB...
Monocblaniydeai (Apetala))
Total Dicotyledons
Monocotyledons
Gymnospcrmae (Coniferae) ..
Total Ph:enogamia
Crj-ptogamia
-^Y f.f\
C
:
Genera.
Species and
varieties.