12 CHARACEA AMERICAN. 
PLATE V. B. 
NITELLA FLEXILIS, Ac. 
Var. Crassa A. Br. Characez Europ. exsic. lol. 
This variety may be distinguished by the large size of the stem as compared 
with its length. The plants are short and stout, generally quite dark green: the leaves are 
not long and the leaflets of the fork are short and thick, nearly always two, very 
rarely three. Fruit is not as commonly found.as in other varieties. 
We have received no specimens south of New York, but many north; from 
Prof. Macoun of Canada, Prof. Bessey of Lowa, Mr. Frost of Vermont, etc. 
Prof. Nordstedt distributes specimens from Sweden, with sporangium and antheridium 
in nearly every fork. The European specimens, like ours, have very short leaflets, beyond 
the fork of the leaf ; and in Europe as in America it is found in more northern regions. 
Explanation of plate V. 
A. WV. flexilis Ag. var. nidifica Wallm. 1, plant natural size. 2, a verticill magnified 
20 diameters. 3, a young branch early transformed into fruit, the young sporangia just 
ready for fertilization. 
B. var. crassa A. Br., natural size. 
