234 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 



e. Annual with tufted roots, plant low, not exceeding .4 dm. 



S. Smiihii, var. setosus. 

 e'. Perennial with running rootstocks; culms sharply trigonous. 

 Scales reddish-brown, ciliate, awn-tipped; achene planoconvex, 



broadly obovoid, short-mucronate *S. americanus. 



Scales yellowish-brown, entire, mucronate; achene trigonous, oblong- 



obovoid, long-mucronate S. Torreyi. 



c". Spikelets more or less loosely umbellulate, or paniculate. 



Achenes 2 mm. long, nearly equalling the scales S. validus. 



Achenes 2.5 to 3 mm. long, much exceeded by the scales. 



S. occidentalis. 

 b'. Involucral bracts 2 or more, leaf -like; culms leafy. 



(From this point use the key in Gray's Manual, ed. 7, beginning at 1.) 



S. acutus Muhl. — (S. occidentalis Man. ed. 7 and 111. Fl. ed. 2; 

 vid. Rhodora, 22: 56, 1920.) 



Borders of lakes and marshes, in shallow water; occasional. Three 

 Mile Pond, Sheffield; Lake Buell, New Marlboro; Marsh Pond, 

 Egremont OYalters). 



S. americanus Pers. — Sandy shores; occasional. Big Pond, 

 Otis; Stockbridge Bowl, Stockbridge. 



S. atrocinctus Fernald. — Wet meadows, borders of streams and 

 ponds, marshes; common, especially on the upland. A form with a 

 pale involucre from Washington. 



forma brachypodus (Fernald) Blake. — Vid. Rhodora, 15: 161 

 (1913). 



Occasional with the type on the plateau. Savoy; Washington; 

 Becket. 



S. atrovirens Muhl. — Low ground; common. 



var. georgianus (Harper) Fernald. — {S. gcorgianvs Man. ed. 7; 

 8. atrovirens 111. Fl. ed. 2 in part. Vid. Rhodora, 23: 134, 1921.) 



Low ground; occasional. Greylock (Winslow^; Lanesboro (Chur- 

 chill); Sheffield. Not noted on the plateau. 



forma sychnocephalus (Cowles) Blake. — Vid. Rhodora, 16: 

 161 (1913). 



Roadside ditch, New Marlboro; Egremont. 



S. cyperinus (L.) Kunth. — Wet meadows and marshes, river 

 swales; frequent. 



var. pelius Fernald. — Wet meadows, borders of rivers and lakes, 

 marshes; common. 



var. pelius, forma condensatus (Fernald) Blake. — Vid. Rhodora, 

 15: 162 (1913). 



