274 GENUS ATRIPLEX. 



of the plant, the staminate confined to a few of the upper axils; perianth 5-cleft in the 

 staminate flowers, wanting in the pistillate; fruiting bracts sessile, thick, united nearly 

 to apex, ovate, acute, 2 to 3 mm. long, 1.5 to 2.2 mm. broad, not margined, sparsely and 

 minutely toothed along the edges, the faces bearing a few short acute tubercles, especially 

 across the middle; seed, 1 to 1.2 mm. long, yellowish-brown; radicle superior. 



Known only from southwestern Wyoming and eastern Utah. Type locality, Gunnison, 

 Utah, altitude about 1,600 m. Collections: Type collection, September 15, 1900, Jones 

 6525 (Herb. Jones, NY, St. Louis, UC) ; Rock Springs, Wyoming, August 9, 1896, Greene 

 (R, NY, UC, type collection of A. greenei Nelson, minor variation 1). 



MINOR VARIATION. 



1. Atriplex greenei Nelson, Bot. Gaz. 56: 65, 1913. — Differs in having narrowly linear leaves, the larger of 

 which are 1 to 1.5 cm. long by only 1.5 mm. wide, and in the bracts, which are described as appendaged at the 

 middle or above. The leaves in the type of tenuissima are described as oblong to lance-ovate or broader, 1 to 7 

 mm. long; in the only material now at hand (duplicates of the type) they are mostly ovate to linear-oblong, the 

 widest 5 mm. long by 2.5 mm. wide. But proceeding down the stem, the leaves progressively approach the 

 linear shape of greenei, one measuring 6.6 mm. long by 2 mm. wide. The bract differences are as described as 

 far as the general tendency is concerned. That the difference in the distribution of the appendages is not so 

 sharp as supposed is indicated by the accompanying text-figures. The single collection thus far made of each 

 of these forms does not furnish sufficient evidence for the final disposal of A. greenei, either as a distinct species 

 or as a minor variation of A. tenuissima, but from the nature of the differentiating characters it is predicted 

 that intermediate forms will be found, in which case the latter will be the preferred course. 



Fio. 34. — Fruiting bracts of Atriplex tenuissima to illustrate the distribution of appendages in the type and in a minor varia- 

 tion: a, b, c, d, bracts from the type specimen (Missouri Botanical Garden Herbarium); e, /, g, bracts from the 

 type specimen of minor variation 1, A. greenei Nelson (Rocky Mountain Herbarium); h, bract from a duplicate 

 of A. greenei (New York Botanical Garden Herbarium). All X 6. 



RELATIONSHIPS. 



Atriplex tenuissima is most closely related to A. pusilla, but is sharply set off by its 

 more numerous flowers in each of the glomerules and especially by its larger and con- 

 stantly tuberculate fruiting bracts and larger seeds. The relationship to this species and 

 the probable origin of the group are discussed under A. pusilla. In describing the type, 

 which is at the herbarium of the Missouri Botanical Gardens, Nelson says that only the 

 pistillate plant was seen. However, the species is not dioecious, for duplicates of the 

 type collection bear both kinds of flowers. It is probable that the staminate flowers 

 had all matured and dropped from the plant examined by Nelson. In the only other col- 

 lection (Rock Springs, Wyoming, Greene) the plants are also monoecious. 



ECOLOGY AND USES. 



Nothing is known concerning the ecologic relations of this species, but probably they 

 are similar to those of A. pusilla. It has no uses. 



16. ATRIPLEX PARISH] Watson, Proc. Am. Acad. 17:377, 1882. Plate 41. Brittlescale. 

 Erect but often seemingly prostrate rigid annual herb, 0.5 to 2 dm. high, widely 

 branched throughout; branches numerous, rather stout, brittle, often horizontally spread- 

 ing, coarsely white-scurfy, the scurf sometimes so long as to simulate a true pubescence, 

 tardily glabrate, faintly tinged with red; leaves varying from all opposite to mainly alter- 

 nate, numerous, the upper ones imbricate, closely sessile, ovate, the lower lanceolate, 



