North American Cyycracea-. 321 
Obs. This species was first described by Pursh, but it is 
undoubtedly the S. dchilis of Muhlenberg, and was so named 
by him many years before Pursh's Flora was published. Mr. 
Arnott in a note under S. junciformis of N. ab Esenbeck, (in 
Wight'' s conirib, p. 112) states that our S. dehilis, which he 
received from B. D. Greene, Esq. and myself, is identical with 
the East India species ; but on comparing my specimen of S. 
jicnciformis given to me by Mr. Arnott, and named by Nees 
himself, with our S. dchilis, I observed sufficient differences to 
induce me to think them distinct. The former has a much 
larger, pale (not blackish brown) nut, and the bristles are much 
more slender and scarcely as long as the nut. The S. Wullichiiy 
N. ah E. (1. c), of which I also have a specimen from Mr. 
Arnott, seems to be scarcely distinct from S. junciformis. 
In my southern specimens of S. dehilis from Dr. Baldwin's 
herbarium, there are sometimes seven spikes in a cluster upon 
one culm. The spikes are longer, and the nut also blacker 
and with deeper punctures than in the northern plant. 
6. SCIRPUS LACUSTRIS, LhllU 
Culm terete, leafless ; umbel compound, growing from the 
side of the culm near its summit ; spikes ovate or ovate-oblong; 
scales ovate, mucronulate, ciliate ; style bifid ; nut obovate, 
plano-convex, shorter than the bvisdes. 
S. lacustris, Linn. ; Willd. sp. 1. p. 296 ; R. Brown, prodr. 1. p. 223; 
Smith, Eng.fl. 1. p. 56; Ram. &; Schutt. syst. 2. p. ]38; Michx.! fl. 1. 
p. 31; Pursh, fl. 1. p. 5o; Elliott, sk. 1. p . 31; Muhl. ! gram. p. 32; 
Torr.Ifl. 1. p. 48; Beck, hot. p. 425; Gray! Gram. ^ Q/p. part 2. 
no. 136; Darlingt.! fl. Cest. ed. 2. p. 21. 
S. acutus, Muhl. ! gram. p. 33; Big.fl. Bosl. ed.2. p. 31; Torr.! fl. 
1. p. 49; Beck, bat. p. 425. 
S. validus, Vdhl, enum, 2. p. 268 ; Pursh ! fl. 1. p. 56 ; Rcem. Sf Schult. 
syst. 2. p. 138 ; Spreng. syst. 1. p. 209. 
Culm 3 — 8 feet high, gradually tapering upward, smooth, tough, filled 
■with a spongy pith, sometimes marked with oblong dark brown spots ; 
