Norih American Cyperacea. 321 



Oes. This species was first -described by Pursh, but it is 

 undoubtedly the S. dehiUs (A MuHenberg, 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 contrih. p. 112) states that our ' <S. debilis, which he 

 received fromB. D. Greene, Esq. and myself, is identical with 

 the East India species ; but on comparing my specimen of <S, 

 junciformis given to me by Mr. Arnott, and named by Nees 

 himself, with our S. debilis, 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. Wallichii, 

 N. ab E. (1. c), of which I also liave a specimen from Mr. 

 Arnott, seems to be scarcely distinct from S. junciformis. 



In my southern specimens of S. debilis 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, Liun. 



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 bristles. 



S. lacustris, Linn. ; Willd. sp. 1. p. 296 ; R. Broivn, prodr. 1. p. 223; 

 Smith, Eng.fl. 1. p. 56; Ram. SfSchult. syst. 2. p. ]38; Michx.Ifl. 1. 

 p. 31; Pursh, Jl. 1. p. 55; Elliott, sk. 1. p . 31; Muhl.! gram. p. 32; 

 Torr. ! fl. 1. p. 48 ; Beck, hot. p. 425; Gray! Gram. Sf- Cyp. part 2. 

 no. 136; Darlingt.! jl. Cest. ed. 2. p. 21. 



S. acutus, Muhl. ! gram. p. 33; Blg.fl. Bost. ed.2. p. 31; Torr.! Jl. 

 1. p. 49; Beck, hot. p. 425. 



S. validus, Vahl, enum, 2. p. 268 ; Pursh ! Jl. 1. p. 56 ; Ram. Sf Schult. 

 syst. 2. p. 138 ; Spreng. syst. 1. p. 209, 



Cuhn 3 — 8 feet high, gradually tapering upward, smooth, tough, filled 

 with a spongy pith, sometimes marked with oblong dark brown spots ; 



