64 FLOEA OF PHILADELPHIA. 



Bristles downwardly barbed, about equalling the achene. 



4. S. debilis. 

 Bristles minute or wanting. 5. S. Smithii. 



Culms sharply 3-angled; plants perennial by rootstocks. 



Achene plano-convex, bristles shorter than or equalling the 

 achene. 

 Spikelets acute, much overtopped by the slender involucral 



leaf; scales awned. 6. S. Americanus. 



Spikelets obtuse ; involucral leaf short, stout ; scales 

 mucronulate. 7. S. Olneyi. 



Achene 3-angled, ridged on the back. 8. S. mucronatus. 



Spikelets several or numerous, umbelled; tall sedges. 



9. S. lacustris. 

 Spikelets several, capitate or umbellate, large ; involucral leaves 2 or more. 

 Achene lenticular or plano-convex; spikelets capitate. 



10. S. robustus. 

 Achene sharply 3-angled; spikelets umbellate. 11. S. fluviatilis. 



Spikelets very numerous in compound umbels or umbelled heads, small; in- 

 volucral leaves several; tall sedges. 

 Bristles downwardly barbed; spikelets in umbelled heads. 



Bristles equalling or slightly exceeding the achene ; leaves 6-16 mm. 

 wide. 

 Style 3-cleft; achene 3-angled; bristles 6. 



Spikelets 3-8 in each head; bristles barbed throughout; 



scales obtuse. 12. S. sylvaticus. 



Spikelets 8-20 in each head; bristles not barbed below; 

 scales acute. 13. S. atrovirens. 



Style 2-clef t ; achene plano-convex ; bristles 4. 



14. S. microcarpus. 

 Bristles flexuous, twice as long as the achene ; leaves 4-6 mm. 

 wide. 15. S. polyphyllus. 



Bristles smooth or slightly pubescent ; umbel mostly decompound. 



16. S. cyperinus. 



1. SciRPUS NANUS Spreng. M. p. 176. Brackish marshes. Summer. 



New Jersey/— Frequent. 



2. SciRPUS PLANiFOLius Muhl. M. p. 176. Woods and thickets. Summer. 



Philadelphia— BjhevTj, Mart. (B. C), Old York Eoad (Te.), Wissa- 

 hickon (VP.). Bmc/c-s — Eock Hill (Fr,), Montgomery — Green Jjane 

 (VP.). Delaicare—lthan's Bridge, Dr. Geo. Smith (Fu.) (B. Sm.), Ead- 

 nor, Castle Eock (VP.). Chester— (P.). Lancaster— Lancaster (Kr.), 

 BerAs— (P.). Northampton — Easton, Porter (B. C). 



Gloucester — MnWica Hill (C), Miekleton (He.), Swedesboro (Li.). 

 Mercer— Princeton (C). 



New Castle — General and frequent. 



3. SciRPUS suBTERMiNALis Torr. M. p. 176. Slort- streams and ponds. 



Summer. 

 Burlington — Batsto, Quaker Bridge (C), Brown Mills, West Creek 

 (Te.). Caif/fZe)!— Longacoming (C), near Cedar Brook (VP.). Glouces- 

 ter — Swedesboro, Eepaupo (Li.). Atlantic — Hammont on (Fr.), Mill 

 Pond near Atlantic City (He.), Bakers ville (Li.). Ocean — Toms Eiver 

 (C), Forked Eiver (He.). 



4. SciRPUS DEBILIS Pursh. M. p. 177. Swamps. Summer. 



Philadelphia — Bjherry, Mart. (B. C). Bucl's — Boek Hill (Fr.). 

 Montgomery— (P.). Delaware— Bhoads' Swamp (Fu.), Eidley Creek near 

 Media (B. Sm.). Chester— (P.). Lancaster— (P.). Lehigh— (P.). 

 Nortliampt on — Easton, Porter (B. C). 



