FLOWERING PLANTS AND FERNS OF ARIZONA L63 



4. Scirpus americanus Pers., Syn. PL 1: 68. 1805. 



Apache, Navajo, and Coconino Counties, southward to Cochise 

 and Maricopa Counties, 1,000 to 5,000 feet. Throughout the temper- 

 ate part of North America; South America. 



This wiry-stemmed plant occurs often in saline marshes. 



5. Scirpus olneyi A. Gray, Bost. Jour. Nat. Hist. 5: 238. 1845. 

 Apache and Coconino Counties southward to Cochise and Pima 



Counties, 1,000 to 7,000 feet. New Hampshire to Florida, westward 

 to Oregon, California, and Mexico. 



6. Scirpus microcarpus Presl, Keliq. Haenk. 1: 195. 1828. 



Oak Creek, Coconino County (Fulton 9680), Chiricahua Mountains, 

 Cochise Countv {Blumer 1552), Rincon Mountains, Pima County 

 [NeaMey 162), 4,000 to 6,000 feet. _ Nova Scotia to Alaska, southward 

 to New Mexico, Arizona, and California. 



7. Scirpus pallidus (Britton) Fernald, Rhodora 8: 163. 1906. 



Scirpus atroiirens Muhl., var. pallidus Britton, N. Y. Acad. Sci. 

 Trans. 9: 14. 1889. 



White Mountains, Apache County (Griffiths 5422). Manitoba to 

 Kansas, Colorado, and Arizona. 



4. ELEOCHARIS. « Spikerush 

 Contributed by H. K. Svenson. 



Plants leafless, glabrous throughout ; inflorescence a single spikelet, 

 bractless, with spiral to distichous scales, the lowermost frequently 

 sterile; stamens 3 or 2; style with 3 or 2 branches, fimbriate; achenes, 

 trigonous to biconvex, usually with a prominent style base (tubercle), 

 this articulated or constricted at base; surface of the achene smooth to 

 reticulate. 



This genus differs from Fimbristylis in the glabrous, always single- 

 headed inflorescence; and from single-headed species of Scirpus in 

 the fimbriate style, bractless inflorescence, and firm (not spongy) 

 achene surface. The plants grow mostly in wet soil, in marshes, 

 springy places, and along streams. 



Key to the species 



1. Achenes biconvex (lenticular) ; styles normally bifid but frequently trifid in 



E. engelmanni and E. nodulosa (2). 



2. Plants annual; style base (tubercle) much less than one-third as high as the 



achene (3). 



3. Spikelets ovate to lanceolate; mature achene brown; style base very low, 



about as wide as the truncate achene and not differentiated in color. 



1. E. ENGELMANNI. 



3. Spikelets globose; mature achene black; style base whitened, usually 



pointed, less than one-third as wide as the achene 2. E. genictjlata. 



2. Plants perennial, with creeping rootstocks, often stoloniferous; style base 



much narrower than the achene, deltoid to elongate: species difficult to 



distinguish (4). 



16 References: Fernald, M. L.; and Braceett, a. E. the representatives of ej kovu leus paj ostbis, 

 IN NORTH AMERICA. Rhodora 31 : 57 77. 1929. 

 Svenson, h. K. monographic studies in the genus eleocharts. Rhodora 31: 121-135, 

 152-163. 167-191, 199-219, 224-242. 1929. Ibid. 34: 192-203, 215 227. 1932. [bid. 36: 



377-389. 1934. Ibid .39: 210-231, 236-273. 1937. Ibid. 41: 1-19, 43-77, 90-110. 1939. 



