34 Flora of the Palousc Region 



Flowers of the spikeletall,or atleastone ofthem perfect: spikelets all similar. 

 Spikelets flattened: scales 2-ranked. 54. cyperus. 



Spikelets not flattened: scales in a spiral. 



Base of style swollen, persistent as a tubercle on the akene. 



55. ELEOCHARis. 

 Base of style not swollen, deciduous or persistent as a subulate tip. 

 Bristles present; hyaline scales none. 56. scirpus. 



Bristles none; perianth of a single minute posterior scale. 



57. HEMICARPHA. 



Flowers monoecious or dioecious, usually borne in separate spikes. 



58. CAREX. 



54. CYPERUS. 



Annual or perennial: stems simple, triangular, leafy near the 

 base, and with one or more leaves at the summit which form an 

 involucre for the simple or compound umbellate or capitate inflor- 

 escence: rays of the umbel sheathed at the base, usually very un- 

 equal, one or more of the heads or spikes commonly sessile: spike- 

 lets flat or roundish: scales concave, 2-ranked, all flower-bearing 

 or the lower ones empty: flowers perfect: perianth none: stamens 

 1-3: akene 3-angled. 



Rachis naked. 



Scales tipped with recurved awns. C. ixflexus. 



Scales acuminate, not awned. C. acuminaTus. 

 Rachis winged. 



Wing of rachis persistent, continuous. C. esculentus. 



Wing of rachis separating from it as small scales. C. eryThrorhizo.S 



C. inflexilS Muhl. Annual: stems 1-15 cm. tall, ascending: leaves flat, 

 about 1 mm. wide, often curved, about equalling the stems: bracts much ex- 

 ceeding the inflorescence: spikelets ovate-lanceolate, 3-5 mm. long, in dense 

 heads, terminating the branches of an unequally rayed umbel, or rarely all 

 aggregated into a single compound head: scales green, becoming brown, all 

 with strongly recurved awn-like tips. Stream banks, common. 



C. acuminatus Torrey. Much like the preceding, usually taller: 

 spikelets pale green, oblong-lanceolate, the scales merely acuminate, the 

 tips slightly recurved. Banks of Snake River at Almota, rare. 



C. esCUlentUS L. Perennial, with horizontal tuber-bearing rootstocks: 

 stems 30-60 cm. tall: leaves flat, 4-5 mm. long, exceeding the stem: invol- 

 ucral leaves as long as the others, far exceeding the inflorescence: umbel 

 usually simple or nearly so, the rays very unequal, the spikelets arranged in 

 loose spikes; spikelets linear, diverging, mostly two-ranked, 8-12 mm. long; 

 scales yellowish or rusty, strongly-nerved, scarious-margined, the green mid- 

 ribs ending in very short points: wing of the rachis narrow, not becoming 

 divided into scale-like parts. Banks of Snake River, rare. 



C. erythrorhizOS Muhl. Annual: stems usually 15-60 cm. tall, sometimes 

 much smaller: leaves flat, commonly 2-4 mm. broad, shorter than the stem; 

 involucral leaves 4-S, broad at base, far exceeding the inflorescence: spike- 

 lets bright chestnut, linear, 5-6 mm. long, densely crowded into flattened 

 spikes, 1-3 cm. long, the latter umbelled on the unequal branches of the 

 primary umbel: scales oblong, keeled, the green midrib prolonged into a 



