II. Tidal marsh 



Scirpus americanus, Three-Square Rush 



Rhizomes stout and hard, dark brown; upper sheath concave, but not 

 notched, bearing an elongate, linear, sharp, pointed blade; spikelets 

 many in sessile clusters, reddish-brown; involucre appears to be con- 

 tinuation of stem, long to 15 cm, acute ; plants of brackish to fresh- 

 water borders of marshes, usually in almost pure stands. 



Flgfure 102. — Stem, flower cluster 

 and involucre X2. 



Scirpus paludosus var. atlanticus, Bayonet Grass 



Growing from a cormlike enlargement of the rhizome; stems 

 three-angled; leaves boi'ne chiefly or wholly below the middle of 

 the stem; two or three involucral bracts; in borders of brackish 

 ponds and on tidal marshes. 



Figure 103.— Habit sketch X '/lo. 



Scirpus torreyi, Torrey's Rush 



Rhizome flaccid, brownish; upper sheath readily splitting, leaves triangular chan- 

 neled with obliquely rounded tips; spikelets in sessile clusters, oblong-lanceolate, 

 reddish-brown; involucre appears to be continuation of stem; 3-5 cm long; plants 

 along brackish to freshwater margins of ponds and marshes. 



41 



