Flora of the Paloasc Region 35 



short, mucronate tip: wings of the rachis separating to the hase, forming 

 pairs of small scales. Banks of Snake River, frequent. 



55. ELKOCHARIS. 

 Annual or perennial: steins simple, triangular, cpiiadrangular, 

 terete, flattened or grooved, the leaves reduced to sheaths or the 

 lowest very rarely blade-bearing: spikelets solitary, terminal, erect, 

 several many-flowered, not subtended by an involucre: scales con- 

 cave, in a spiral: perianth of 1-12 bristles usually barbed: stamens 

 2-3: akene 3-angled, but sometimes appearing turgid: base of the 

 style persistent on the summit of the akene forming a terminal 

 tubercle. 



Spike small, few- flowered: akene 3-angled. E. acicularis. 



Spike many-flowered: akene biconvex. E. palustris. 



E. acicularis R. & S. Perennial by creeping rootstocks, usually forming 

 extensive mats: stems very slender, 7-15 cm. tall, erect: spikes 3-10-flowered, 

 3-5 mm. long: bristles 3-4, shorter than the akene, or wanting: akene oblong 

 or obovoid, somewhat 3-angled, marked with 9-12 longitudinal ribs, with 

 very numerous cross-lines between them: tubercle broad, contracted at its 

 junction with the akene: style 3-cleft. Very abundant in wet places. 



var. bella Piper n. var. Rootstocks very short, so that the plant forms 

 dense round tufts 5-10 cm. in diameter: stems ascending or spreading, only 

 2-5 cm. long: otherwise as in the species. Rare on muddy banks of streams. 

 In habit very different from E. acicularis, but lacking good morphological 

 characters. In marked contrast to E. acicularis, the variety produces akenes 

 freely. The type is Piper No. 3055, Pullman, Aug. 1899. 



E. palustris R- & S. Rootstocks extensively creeping: stems 30-70 cm. 

 tall: spike lanceolate-oblong, 1-2 cm. long: bristles 4, usually exceeding the 

 obovate smooth biconvex akene: tubercle obtuse, contracted at its junction 

 with the akene: style 2-cleft. Abundant at the edges of ponds or in shallow 

 water. 



56. SCIRPUS. 

 Annual or perennial: stems leafy or the leaves reduced to basal 

 sheaths: spikelets terete (in ours), umbellate (in ours), subtended 

 by a i-several-leaved involucre, which is rarely wanting: scales in 

 a spiral, usually all fertile, the 1-3 lower sometimes empty: flowers 

 perfect: perianth usually of 1-6 bristles: stamens 2-3: style 2-3- 

 cleft, not swollen at the base: akene triangular, lenticular or plano- 

 convex. 



S. microcarpus Presl. Perennial, the stout stems about 1 m. tall: leaves 

 8-10 mm. broad, smooth beneath, rough on the margins and upper surface 

 of the midvein, the upper leaf usually exceeding the stem: inflorescence a 

 two to three times compound umbel, {he primary rays 3 -10 cm. long, unequal: 

 bracts leaf-like, about equallingthe inflorescence: spikelets ovoid, numerous, 

 dark green, 3-5 mm. long, in heads of 3-12 or more: scales broadlv ovate, 

 acute: stamens 2: styles bifid: bristles 4: nutlet white, oblong-lenticular, very 

 short-beaked. Common on the margins of ponds and streams. 



57. HEMICARPHA. 

 Mostly annual, low tufted plants: stems and leaves erect or spread- 



