234 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
e. Annual with tufted roots, i)lant low, not exceeding 4 dm. 
S. Smithii, var. setosus. 
e'. Perennial with runninp rootstocks; culms sharply trigonous. 
Scales reddish-bnnvn, oiliate, awn-tipped; achene planoconvex, 
broadly obovoid, short-mucronate S. americanus. 
Scales yellowish-brown, entire, mucronate; achene trigonous, oV:)long- 
obovoid, long-mufTonate S. Torreyi. 
c". Spikelets more or less loosely umbellulate, or paniculate. 
Achenes 2 mm. long, nearly equalling the scales S. validus. 
Achencs 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 (Walters). 
S. americanus Pers. — Sandy shores; occasional. Big Pond, 
Otis; Stockhridge 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. — T7f/. 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. gcorgianus Man. ed. 7; 
8. atrovireus 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, 15: 
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). 
