530 CYPEEACE^E. (SEDGE FAMILY.) 



orbicular, strongly wrinkled ; tubercle compressed, very short, sessile, but not 

 decurrent on the edges of the nut. (Scirpus nitens, Vahl.) Shallow pine- 

 barren ponds, Florida to North Carolina. July. Culms commonly root- 

 ing at the lower joints. 



P. SCIRPOIDES, Torr., if within our limits, may be known by its nearly smooth 

 nut, and slender beak-like decurrent tubercle. 



18. DICHBOMENA, Eichard. 



Spikes compressed, few-flowered, aggregated in a terminal head, and sur- 

 rounded by an involucre of several leaves, which are commonly white at the 

 base. Scales imbricated in few rows, most of them bearing abortive flowers. 

 Stamens 3. Style 2-cleft. Nut lenticular, crowned with the broad and persist- 

 ent base of the style. Perianth none. Perennials. Culms jointless, leafy at 

 the base. Scales white, membranaceous. 



1. D. leucocephala, Michx. Culms (l-l high) slender, 3-angled ; 

 leaves narrowly linear ; involucre of 4 - 7 narrow leaves ; nut orbicular, wrinkled ; 

 tubercle flat, broadly conical, sessile, but not decurrent. Damp soil, Florida to 

 North Carolina. Aug. and Sept. Involucre unchanged in drying. 



2. D. latifolia, Baldw. Culms stout (2 -3 high), nearly terete; leaves 

 broadly linear, elongated ; leaves of the involucre 8-9, tapering from the broad 

 (3" -4" wide) base to the slender summit, becoming reddish ; nut round-obovate, 

 faintly wrinkled ; tubercle flat, conical, obtuse, the sides decurrent on the edges 

 of the nut. Low pine barrens, Florida to North Carolina. May - July. 

 Heads larger than those of the preceding. 



19. CLADIUM, Browne. 



Spikes ovate, 1 - 2-flowered. Scales loosely imbricated, the lower ones empty. 

 Perianth none. Stamens 2. Style 2 - 3-cleft, the divisions often 2 - 3-cleft, de- 

 ciduous. Nut globose-ovate, the pericarp thickened and corky near the apex. 

 Tubercle none. Culms tall. Spikes disposed in axillary and terminal cyme- 

 like panicles. 



1. C. efifusum, Torr. (SAW-GRASS.) Culms (4- 8 high) nearly terete; 

 leaves linear, elongated, saw-edged ; panicles numerous, diffuse ; spikes small, 

 3 - 4 in a cluster, deep brown ; scales about 6, the uppermost bearing a perfect 

 flower, the next below staminiferous, the others empty ; nut ovate, pointed, 

 wrinkled. (Schoenus effusus, Swartz.) Fresh or brackish marshes along the 

 coast, Florida to North Carolina, and westward. July and Aug. 



20. SCLERIA, L. NUT-RUSH. 



Flowers monoecious. Sterile spike few - many-flowered.^ Scales loosely im- 

 bricated in 2 - 3 rows. Fertile flowers solitary, separate or at the base of the 

 sterile spike. Stamens 1-3. Style 3-cleft. Nut globose or ovate, stony or 

 bony. Chiefly perennials, with creeping rootstocks, and triangular leafy culms. 

 Spikes clustered, lateral and terminal. 



