FLOWERING PLANTS AND FERNS OF ARIZONA 155 



1. Tripsacum lanceolatum Rupr. in Fourn., Mex. PL 2: 68. 1886. 



Tripsacum lemmoni Vasev, Contrib. U. S. Natl. Herbarium 

 3:6. 1892. 



Mule Mountains and Huaebuca Mountains (Cochise County), 15 

 miles from Patagonia (Santa Cruz County), rocky hills, type of T. 

 lemmoni from the Huachuca Mountains (Lemmon 2932). Southern 

 Arizona to Guatemala. 



9. CYPERACEAE. Sedge family 



Plants herbaceous, grasslike or rushlike; flowering stems often 

 triangular, usually solid, from fibrous roots or from rootstocks, these 

 sometimes bulblike or bearing tubers; leaves with narrow sometimes 

 terete blades, the sheaths closed, the blades sometimes wanting; 

 flowers subtended by 2-ranked or spirally imbricate scales (some of 

 these often empty), arranged in spikelets; stamens 1 to 3; ovary 

 1 -celled; ovule 1; fruit an achene. 



A family of large size but very little economic importance, the com- 

 monly tough and wiry herbage giving the plants small forage value as 

 compared with that of the grasses. The fact that most of the gre- 

 garious species occur in marshes makes their value as soil binders 

 negligible. 



Key to the genera 



1. Achene enclosed in a perigynium (saclike, often beaked envelope with an 

 apical opening through which the styles protrude); flowers none of them 

 perfect, the staminate and pistillate ones in separate spikes or in the 



same spike 8. Carex. 



1. Achene not enclosed in a perigynium; flowers all perfect or, if some of them 

 imperfect, then the staminate and pistillate ones not sharply segregated as 

 above (2). 

 2. Spikelets with scales in 2 rows, the spikelets often strongly flattened; empty 



basal scales not more than 2; perianth bristles none 2. Cyperus. 



2. Spikelets with scales mostly spirally imbricate around the axis in several 

 rows, the spikelets terete or not strongly flattened (3). 

 3. Base of the style noticeably enlarged (4). 



4. Thickened base deciduous with the rest of the style; spikelets several, 

 in capitate or umbellate clusters; perianth bristles none; achenes 



biconvex or lenticular 5. Fimbristylis. 



4. Thickened base persistent after the rest of the style has fallen (5). 

 5. Steins leafless or their leaves reduced to sheaths; spikelet solitary; 

 perianth bristles usually present; style base conic or bulbous, 

 large; achenes biconvex, lenticular, or triangular. 



4. Eleocharis. 



5. Stems usually bearing one or more leaves with filiform blades; spikelets 



solitary or several in cymose clusters; perianth bristles none; 



style base apiculate, small; achenes triangular. 6. Bulbostylis. 



3. Base of the style not noticeably enlarged (6). 



6. Stamen 1; bristles none; achene nearly cylindric; plant dwarf, with 

 filiform stems and leaves; spikelets not more than 3 mm. long. 



1. Hemicarpha. 



6. Stamens 2 or 3; perianth, if any, represented by 1 or more bristles (7). 



7. Flowers all perfect; spikelets with not more than 2 empty basal scales; 



perianth bristles usually present; achene triangular, lens-shaped, 



or plano-convex; leaf margins not spin ulose _ 3. Scirpus. 



7. Flowers often partly staminate, only the one or two uppermost ones 

 perfect; spikelets with 3 or more empty basal scales; perianth 

 bristles none; achene ovoid or globose; leaf margins spinulose- 

 serrate 7. Cladiu.m. 



