A. CORDULATA. 



269 



varying to a single minute scale and entirely disappearing in many cases. It possesses 

 no value in classification and its presence or absence can not be used as a taxonomic crite- 

 rion. Finally, many other features of this remarkable plant are also variable, giving to the 

 species a degree of plasticity which enables it readily to adapt itself to varying ecologic 

 conditions. Some of these additional variations were responsible for A. draconis Jones, 

 a proposed species reduced to A. phyllostegia on evidence supplied by the type specimens, 

 which were generously made available by Professor Jones. (See further under minor 

 variation 2 of the above Hst.) 



Table 25. — Variation in pistillate flowers of Atriplex phyllostegia. 



' Watson included two collections under his 986, either of which may be taken as the type. Both are from western 

 Nevada and no perianth has been found in either of them. 



> Type of A. draconis Jones, minor variation 2. 



•Ten flowers were examined of this collection; two of these were devoid of perianth, each of the others had 1 or 2 

 small scales. 



• Type of Endolepis covillei Standley, minor variation 3. 



« The result of 10 examinations. 



ECOLOGY AND USES. 



Atriplex phyllostegia may occur in clan-hke groups in strongly saline soil, where it is 

 associated with Sarcobatus, Chrysothamnus nauseosus consimilis, and Distichlis, or it may 

 form families of some size in depressions in fallow fields and alkaline plains, especially 

 where Distichlis has been plowed or otherwise disturbed. It is an indicator of strong 

 alkali, to an amount of 3 to 4 per cent in the first foot, where the roots occur. The plants 

 bloom for an unusually long period, namely, April to September, apparently in conse- 

 quence of the relatively constant water-content. 



This species is doubtless grazed, but it is too inconsiderable to be important. 



12. ATRIPLEX CORDULATA Jepson, Pittonia 2 : 304, 1892. Plate 43. Heartscale. 

 Erect rigid annual herb or spreading as the result of grazing, 1 to 5 dm. high, either sim- 

 ple or branched throughout; branches heavy, rigid, not angled, furfuraceous, glabrate in 

 age, the bark then stramineous and exfoliating; leaves alternate except the lower, closely 

 sessile, ovate, all cordate at base except the lowest which are merely rounded to a slightly 

 narrowed base, acute at apex, 0.5 to 1.5 cm. long, 0.3 to 1 cm. wide, entire, rather thick, 

 heavily coated with a furfuraceous tomentum which is only tardily deciduous, the veins 

 then conspicuous; flowers monoecious, in dense glomerules in the axils of all but the few 

 lowermost leaves, the staminate confined to the upper axils but not forming naked spikes; 

 perianth 4-cleft or 5-cleft in the staminate flowers, wanting in the pistillate ; fruiting bracts 

 sessile or subsessile, lightly compressed, united to about the middle, typically ovate from 

 a broad base, often slightly rounded to a very short stalk, usually broadest below but 



