North Amcriain Cijjjeraccce. 243 
111 airangiiig the Cypeiaceai described in the luliuu ing pages, 
I have adopted the classification of Nees ab Escnbeck, as given 
in the 9th volume of the Linnsea already quoted, without, 
however, agreeing with the learned author in all his views, par- 
ticularly in the extent to which he has divided some of the older 
genera. The characters of his tribes and genera are so brief, 
that I have thought it expedient to enlarge, and in many cases 
to modify them materially. In framing the diagnoses of the 
species, it may be thought by some botanists that I have employ- 
ed characters which are too microscopic, but this course was 
absolutely necessary, since the most certain marks of discrimina- 
tion in this family exist in the minute and highly organized parts 
of fructification, which until lately have been very little regarded 
by botanical writers. The form, texture, relative size, posi- 
tion, &c.*of the scales, perianth, nut, and style, afibrd charac- 
ters on which we can place the most reliance in the Cyperaceae. 
The accompanying table exhibits a view of the North Ameri- 
can genera of this family, arranged according to the Synopsis of 
Nees ab Esenbeck, with the number of species belonging to each 
genus, and the proportion which the endemic species bear to 
those which also inhabit Europe, or other parts of the world. 
Of the Tribe Cyperefe the greatest proportion belong to the 
Southern States. The genus Cyperus itself scarcely extends 
into Canada, and in all New England not more than 7 or 8 species 
have been found. Proceeding south they become more frequent, 
and the maximum is attained in the regions bordering the Gulf 
of Mexico. Kyllingia does not occur north of Pennsylvania. 
Mariscus is found throughout the United States, andDulichiura, 
a doubtful member of this tribe, has an equally extensive range. 
Hypolytreae constitute a small tribe. Lipocarpha is pecu- 
liarly southern, and Fuirena is rarely found as far north as Bos- 
ton ; and, in the northern and middle states, only in the vicinity 
of the ocean. 
Scirpeae are widely distributed, but at least two thirds of the 
species occur south of Virginia. Abildgaardia and Elytrosper- 
mum have only been observed on the Pacific coast of America. 
The genuine species of Scirpus range from the Arctic regions 
to Florida, and from the Atlantic to the Pacific ; and Eleocharis 
