290 GENUS ATRIPLEX. 



with a broad base and widest below the middle (exclusive of the stalk when this is pres- 

 ent). The bracts in both are slightly broader than long. Differences in habit are of 

 assistance at times. A. coronata, as far as known, never assumes the rigid, erect habit 

 of cordulata, but this latter also has branched and spreading forms. 



The type specimens of A. coronata are unsatisfactory in that they are both immature 

 and incomplete. At this stage they display very clearly the subelliptic shape of the 

 leaves, with the bases much narrowed. Some of the bracts are smooth on the sides, and 

 some have low crests. The herbage is well developed and perhaps somewhat flaccid as 

 compared with recent collections, but these latter are all from much overgrazed areas 

 where they have suffered from trampling and hard soil as well as from grazing. 



ECOLOGY AND USES. 



Atriplex coronata behaves much like argentea, though it grows as a halophyte in more 

 alkaline places, and it is not so strongly ruderal. In the original habitat it forms a pioneer 

 consocies in soil containing 2 per cent or more of salt, even being found in the Spiro- 

 stachys zone. The plants bloom from May to July. 



This species is one of the important host-plants of Eutettix. It is grazed to some extent 

 by cattle and sheep in the San Joaquin Valley of California. 



23. ATRIPLEX POWELLI Watson, Proc. Am. Acad. 9:114, 1874. Plate 45. Ribscale. 



Strictly erect annual herb, 1 to 10 dm. high, sparingly branched from the base to form 

 an open pyramidal or columnar plant; branches ascending or erect, slender or moderately 

 stout, somewhat woody and brittle in age, obtusely angled, whitish furfuraceous, gla- 

 brate, the old bark exfoliating in dull white patches; leaves all or mostly alternate, the 

 lower on petioles often as long as the blades, the upper sessile, broadly ovate or rhombic- 

 ovate, rounded or abruptly cuneate at base, acute at apex, 1 to 3.5 cm. long exclusive of 

 petiole, 0.8 to 3 cm. wide, entire, firm, not fleshy, gray especially beneath with a fine 

 scurf, prominently 3-nerved from the base; flowers imperfectly dioecious, some plants 

 purely pistillate, some chiefly staminate, but with a few pistillate flowers in the lower 

 axils, others chiefly pistillate below and staminate above, the flowers all in axillary glom- 

 erules which are exceeded by their subtending leaves; perianth of staminate flowers 4- or 

 5-cleft, wanting in the pistillate flowers; fruiting bracts sessile, thick, united to the sum- 

 mit, broadly spatulate or broadly oblong, ending above in a broad flattened usually 

 truncate green terminal lobe, 3 to 4 mm. long and broad, the faces covered with promi- 

 nent thickened ascending processes, or these sometimes nearly wanting; seed 2 mm. long, 

 greenish-yellow ; radicle superior. 



Alkaline plains from Alberta to eastern Colorado, New Mexico, Arizona, and Utah. 

 Type locality, Arizona. Collections: Rosedale, Alberta, Moodie 4 (US); vicinity of 

 Rosedale, Alberta, Moodie 1182 (DS, NY); near Glendive, Montana, 1883 Ward (US); 

 Shelby, Montana, September 11, 1909, Jones (Herb. Jones); Carson County, South 

 Dakota, Over 3425 (US) ; Wamsutter, Wyoming, Nelson 3673 (R, UC, US) ; Howell Lake, 

 Wyoming, Nelson 5311 (Herb. Jones, type of A. nelsoni Jones, minor variation 1); Lara- 

 mie River, Huttons Grove, Albany County, Wyoming, Nelson 8171 (Or, NY, R, US, 

 type collection of A. philonitra Nelson, minor variation 2); Colorado: Montrose, iS/ieor 

 4929 (NY, US) ; Hotchkiss, Cowen 2185 (Gr, NY, R, US) ; east of Canon City, Hall 11082 

 (UC); Mancos Plains, Brandegee 1277 (UC); Gunnison River, Purpus 212 (UC); Grand 

 Junction, Baker 930 (UC, US); near Dulce, New Mexico, Standley 8149 (US); south of 

 Shiprock, northwestern New Mexico, Hall 11146 (UC); type collection, cultivated from 

 Arizona seed (Gr) ; Holbrook, Arizona. Rushy 796 (US) ; 4 km. south of Adamana, Arizona, 

 Hall 11161 (CI) ; near Green River, Utah, Hall 11037, 11039 (UC) ; 5 km. north of Emery, 

 Utah, Jones 5456 (UC). Other localities represented by collections in the M. E. Jones 



