A. TULARENSIS 271 



well developed the outline sometimes approaches obovate, the bracts then simulating 

 those of the argentea group, even though the body itself is broadest at or below the mid- 

 dle. The bracts most closely resemble those of A. coronata, under which species the 

 differentiating characters will be discussed. 



The phylogenetic position of cordulata at the beginning of the Pusillae seems to be well 

 established. It is less highly specialized than any of the others, each of which has under- 

 gone considerable reduction in the size of the foliage, flowers, fruiting bracts, and seeds. 

 The development of certain other features will be pointed out later. 



There has been no notable development of important variations within A. cordulata. 

 This condition is associated with its restricted distribution. Two habit forms may be 

 recognized, however. These are very unlike in their extreme development, yet all inter- 

 vening stages are known and sometimes both are found at the same locality. They are 

 illustrated even in the type material, which consists of three sheets with identical labels, 

 except that one sheet is noted as the "small, strict form." This holds 2 plants, only 1.5 

 and 2 dm. high, respectively. One is simple-stemmed, the other has one very short 

 branch. The other sheets have much taller and stouter plants, one with 5 branches from 

 the base, each again forked, another with trunk-like leader and several strong lateral 

 branches. Robust and much-branched bushy plants might easily be taken for a distinct 

 species were it not for the close similarity to the simple-stemmed dwarfs in all essential 

 characters and the presence of intermediate forms. Branching from the base is undoubt- 

 edly due to injury to the main shoot, most commonly as the result of grazing. The 

 remarkably strict habit has been noted by Jepson (1. c), who writes: 



"The leaves on the virgate branches are much alike in size and form; they are triple-nerved and almost as 

 broad as long; the lowest are rarely five lines long. The stem is sometimes absolutely strict, but usually the 

 species is distinguished by its virgate branches. Sometimes the stems bear numerous very short branches 

 which, however, rob the plant of nothing of its virgate aspect." 



ECOLOGY AND USES. 



Atriplex cordulata grows in hard, trampled soil that is only moderately alkaline. It 

 may form pure stands in open spots in Salicornia, Frankenia, etc., or occur scattered in 

 Distichlis turf with Heliotropium curassavicum, Hemizonia pungens, or Helianthus annuus. 

 The flowers open from April to September. 



This is a host-plant of Eulettix, the relations of which are described under A. bracteosa. 



13. ATRIPLEX TULARENSIS Coville, Contr. U. S. Nat. Herb. 4:182, plate 19, 1893. 

 Plate 41. 



Erect rigid but slender annual herb, 2 to 10 dm. high, either simple or with strict ascend- 

 ing or erect stems, these sometimes from the base; branches rigid, brittle, terete or very 

 obscurely angled, coarsely white-scurfy, early turning red, glabrate only near the root, 

 many lateral branches of the upper parts arrested in their growth and forming very short 

 imbricate-leaf y shoots in the leaf-axils ; leaves alternate except 2 or 3 lower pairs, sessile 

 or subsessile, ovate to lanceolate, rounded to the base, acute or acuminate at apex, 1 to 2 

 cm. long, 0.4 to 0.8 cm. wide, entire, thin but firm, gray with a dense scurf, l-nerved, 

 sometimes with 2 additional faint nerves from the base; flowers monoecious, in small 

 dense axillary glomerules, the lower of which are purely pistillate, the upper purely stam- 

 inate, the sexes mixing in some of the intermediate axils; perianth 4-cleft in the staminate 

 flowers, wanting in the pistillate, fruiting bracts sessile, lightly compressed, united nearly 

 to summit, ovate in outline or some with narrowed base and then rhomboid and broadest 

 at about the middle, 2.5 to 3.5 mm. long, 2.2 to 3 mm. broad, the thin margins few- to 

 many-toothed, or only erose, the apex usually ending in a prominent ovate acute tooth, 

 the faces neither tubercled nor appendaged but covered with a dense gray scurf; seed 1 

 to 1.2 mm. long, dark brown, shining; radicle superior. 



