4. Juncus mexicanus R. & S. 



Almost identical to /. balticus but culms compressed and usually twisted, and 

 averaging thicker; bract only 2 to 3 times as long as the panicle. /. balticus var. 

 mexicanus (R. & S.) O. Ktze. 



In wet sandy soil on edge of ponds and lakes, infrequent to rare in buffalo- 

 wallow lakes in the High Plains Country and formerly near springs in the Trans- 

 Pecos of Tex., in N. M. (San Miguel, Sandoval, Grant, Lincoln and Otero cos.) 

 and Ariz. (Apache, Navajo, Coconino, Yavapai, Cochise and Santa Cruz cos.), 

 early summer; Tex. to Calif, and s. to cen. Mex. In Mexico and elsewhere the 

 populations of this species usually show a few blades on the upper sheaths, but 

 our populations do not. 



5. Juncus effusus L. var. solutus Fern. & Wieg. Soft rush. Fig. 311. 

 Rhizomes very short, thick, chestnut-color; aerial culms (plus bract) 6-12 dm. 



long, 2-4 mm. thick, strictly erect, very crowded in thick stands, essentially terete; 

 basal sheaths chestnut-brown, bladeless, 5-15 cm. long, apically rounded; panicles 

 30 to 1 00-flowered, appearing as if emerging subterminally from the side of the 

 culm (actually terminal, far-overtopped by the terete pungent bract which is 5 to 

 10 times as long as the panicle and which appears as a continuation of the culm), 

 of a few densely-flowered much-branched unequal branches; bracteoles 3 beneath 

 each flower; perianth parts 2.7-3.3 mm. long, usually brownish; stamens 3, the 

 anthers about equaling the filaments; capsule obovoid, apically obtuse, truncate 

 or even depressed, about equaling or slightly exceeding the perianth. 



Moist sandy soil or shallow fresh water, about ponds and lakes, along streams, 

 sloughs and in marshes and wet depressions, in Okla. (Atoka, Adair, McCurtain, 

 Haskell, Ottawa and Bryan cos.), e. and s.e. Tex., locally abundant, N.M. (San 

 Miguel, Eddy and Taos cos.) and Ariz. (Navajo, Coconino, Gila and Pima cos.), 

 spring. 



This European species is represented in America by several varieties, the com- 

 monest of which is considered to be var. solutus in the eastern states. 



Var. brunneus Engelm. is characterized by having a dark-brown perianth which 

 is firm to almost rigid in texture, appressed to and from slightly shorter than to 

 slightly exceeding the capsule; its segments with narrow scarious scarcely or not 

 at all involute margins. 



Var. exiguus Fern. & Wieg. has a pale-brown perianth that is thin in texture, 

 spreading and about one and one half times as long as the capsule; the segments 

 with broadly scarious more or less involute margins. 



6. Juncus coriaceus Mack. Fig. 312. 



Culms essentially tufted from dark knotty bases, (with bracts) 3-10 dm. long. 

 1-1.5 mm. thick, often arcuate, crowded or not, essentially terete; sheaths buffy 

 or tawny, the lower bladeless or with setaceous rudiments a few mm. long, the 

 upper with long weak curving blades 1-2 mm. broad and strongly involute, ter- 

 minally pungent; panicle 2- to 25-flowered, appearing as if emerging from the 

 side of the culm (actually terminal, far-overtopped by the terete or slightly com- 

 pressed bract which is 3 to 20 times as long as the panicle and which appears as 

 a continuation of the culm), of a few laxly flowered unequal branches; bracteoles 

 3 beneath each flower; perianth parts 3-4 mm. long, brownish, firm, ascending 

 (fl.) or spreading (fr.); stamens 3, the anthers about equaling the filaments; cap- 

 sule nearly spherical or ovoid-spherical, about equaling or slightly exceeding the 

 perianth. 



Moist sand on edge of streams, in water and along edge of lakes and ponds, 

 and in marshes, in Okla. (McCurtain, Pushmataha and Choctaw cos.) and e. Tex., 

 summer; Coastal States, N.J. to Tex. and inland to Ky., Ark. and Okla. 



612 



