A. MICROCARPA. 303 



ECOLOGY AND USES. 



Atriplex elegans typically forms pure or mixed socies in moderately saline areas in the 

 valleys of southern Arizona, where it is associated with A. canescens or A. polycarpa, or 

 both. Recently it has become a common weed in roadsides, fallow fields, and other dis- 

 turbed places, serving as a pioneer of a short secondary succession. Kearney and his 

 associates found as much as 1 per cent of salt in the first foot of soil, and 0.67 per cent 

 in the second. It flowers regularly after the summer rains, but it may also bloom in late 

 spring as a consequence of abundant rainfall. 



This species furnishes excellent grazing, but is limited in amount. According to 

 Thornber, it is used as greens by the Pima Indians, and it is probably a cause of hay- 

 fever to some extent. 



27. ATRIPLEX MICROCARPA (Benthain) Diotrich. Syn. PI. ,5: 536, 1852. Plate 48. 



DoTSCALK. 



Prostrate or procumbent annual herb, commonly much branched to form tangled 

 masses 2 to 10 dm. across and 1 to 4 dm. high, the ultimate branches ascending or erect; 

 sometimes less branched and all of the stems ascending; branches tough, flexuous, 

 obtusely angled or terete, lightly furfuraceous when young, very soon glabrate and then 

 stramineous, the bark persistent, breaking only on old stems; leaves alternate or a few 

 lower ones opposite, numerous, sessile or the lower short-petioled, oblanceolate or spatu- 

 late-elliptic, narrowed at base, acute or obtuse at apex, often mucronulate, 0.5 to 2 cm. 

 long, 0.3 to 0.6 cm. wide, entire, thin, sparsely scurfy and green above, more closely 

 scurfy and gray beneath, 1-nerved; flowers monoecious, the staminate glomerules in 

 the upper axils or rarely a few of the upper glomerules without subtending leaves and 

 thus short-spicate, the pistillate also in axillary glomerules, but these beneath the stam- 

 inate, many of the intermediate glomerules with both staminate and pistillate flowers; 

 perianth deeply 5-cleft in the staminate flowers, wanting in the pistillate; fruiting bracts 

 sessile or very shortly stalked, not compressed, united nearly to the summit, nearly orbic- 

 ular, but with narrowed base and broad summit, obtuse, 1 to 2 mm. long, 1 to 2.2 mm. 

 broad (larger in minor variation 3), entire, except for 1 to several minute teeth across the 

 summit, faces smooth or with a few minute tubercles, l-nerved, not obviously reticulated; 

 seed 0.8 mm. long, light brown; radicle superior. {Obione microcarpa Bentham, Bot. 

 Voy. Sulph. 48, 1844. Not A. microcarpa Waldstein and Kitaibel, 1812, nor A. micro- 

 carpa Bentham, 1870.) 



Near the coast from Los Angeles County, California, to middle western Lower Califor- 

 nia, including the adjacent islands. Type locality, San Diego, California. Collections, 

 all in California and Lower California: San Pedro Hills, near Rocky Point, Los Angeles 

 County, Abrams 3137 (DS, NY, UC, US); Redondo, Los Angeles County, October 15, 

 1903, Brandegee (UC); Avalon, Santa CataHna Island, March, 1901, Trask (NY, US); 

 San Clemente Island, April 26, 1912, Wooton (US); Laguna Beach, Orange County, 

 May 5, 1916, Crawford (UC); La Jolla, near San Diego, Clements 59 (Gr, UC); San 

 Diego, Pahner 330 (Gr, NY); San Quentin Bay, Palmer 717 (Gr, US); Cedros Island, 

 Palmer 755 (Gr, NY, US). Other stations for Lower Cahfornia are given under minor 

 variation 3. 



MINOR VARIATIONS AND SYNONYMS. 



The characters of this species are remarkably constant, there being but httle fluctuation, even in the vege- 

 tative features. This constancy is a common characteristic of sjjecies of limited distribution. The only 

 variation of note is the large-bracted form found near the southernmost limits of the area inhabited and 

 described under No. 3. 



1. Atriplex pacifica Nelson, Proc. Biol. Soc. Wash. 17:99, 1904.— The correct name for those who follow 

 the American rules. According to these rules the name A. microcarpa (Bentham) Dietrich can not be used 

 for this plant because of the earlier A. microcarpa Waldstein and Kitaibel (P. Rar. Hung. 3:278, 1812). This 

 latter, however, is generally considered as synonymous with .1. palula haxtnia, or at most only a minor variation 

 of this. 



