322 GENUS ATRIPLEX. 



5, 1S58, Hayes (Gr); Aztec ruins, northwestern New Mexico, Hall 11126 (UC); near 

 Tiznitzin, northwestern New Mexico, Wooton 2775 (UC); southwestern Colorado, 1875, 

 Brandegee (UC) ; Tornillo Creek, western Texas, Havard 103 (Gr, type of variety tuberata 

 Macbride, minor variation 4); El Paso, Texas, Jones 4^83 (Gr, US); Comacho Plains, 

 Zacatecas, Lloyd 263 (US); type collection. Hacienda del Salad, San Luis Potosi, 1827, 

 Berlandier 1346 (Gr); Mexico, Gregg 462 (Gr, NY, type collection of A. greggi Watson, 

 minor variation 1). 



MINOR VARIATIONS AND SYNONYMS. 



1. Atriplex gregoi Watson, Proc. Am. Acad. 9:118, 1874. — Based upon Gregg's No. 462 from Mexico, 

 which is the typical small-leaved and small-bracted form of A. obovata Moquin, the type collection of which was 

 also cited by Watson as representing his species. Quite probably Moquin's name was overlooked by Watson. 



2. A. jONEsi Standley, N. Am. Fl. 21 :65, 1916. — Based upon A. sabulosa Jones, which see. 



3. A. SABULOSA Jones, Contr. West. Hot. 11:21, 1903.— When originally described this was not compared 

 with A. obomta, which doubtless was overlooked, but it is a northern large-leaved and large-bracted form of 

 this species. Genuine obovata has leaves only about 1 cm. long by 0.5 to 0.7 cm. wide and bracts correspondingly 

 small. In the type of sahdosa the leaves are about 2.5 cm. long by 1 cm. and more wide, the bracts 6 mm. 

 broad. The two forms are not entirely geographic, for in specimens from as far south as Zacatecas (Lloyd 253) 

 there are leaf -blades as large as 1.7 by 0.9 cm. and bracts 5 mm. broad; while in some from El Sauzal, Ari- 

 zona (September 5, 1858, Hayes) the largest blades are only 1.2 by 0.5 cm. and the bracts 5 mm. broad. As 

 intermediate in size of leaf and bracts may be cited: El Paso, Texas, Jones 4183 (Gr); western Texas, Wright 

 57S (Gr). After changing the name of sabulosa to jonesi (because of the earlier A. sabulosa Rouy), Standley 

 characterizes this as having bracts smooth or rarely slightly tuberculate on the sides, while obovata is described 

 as having crested, sparsely tuberculate, or rarely smooth bracts (Standley in N. Am. Fl. 21 :38 and 66, 1916). 

 The decidedly unreliable nature of this character is now well known (see under Criteria, p. 242, and compare 

 Macbride, Contr. Gray Herb. N. S. 53: 10, 1918). Moreover, the original description of obovata reads: "bracteis 

 * * * disco inappendiculatis." It is true that most of the large-leaved northern plants have broad fruiting 

 bracts which are smooth or with only 2 small thickenings on the side, but not infrequently there may be found 

 on single plants all variations from smooth to as strongly crested as in any yet collected in Mexico (e. g., Winslow, 

 Arizona, at the type locality of sabulosa, Hall 11174, UC). It seems, therefore, that sabulosa is, at the most, 

 only an ecologic form of obovata. This conclusion was predicted by Standley at the time he made the above- 

 mentioned transfer of names (see BuU. Torr. Club 44:425, 1917). 



4. A. OBOVATA var. tuberata Macbride, Contr. Gray Herb. 53:11, 1918. — Marked only by having some of 

 the fruiting bracts copiously tuberculate. Type locality, Tornillo Creek, Texas. The negative value of the 

 tubercle character as a taxonomic criterion is indicated under No. 3. 



RELATIONSHIPS. 



This species is most closely related to A. nuttalli. Both seem to have originated in 

 Mexico, where the present species still maintains a foothold. The fruiting bracts are 

 broader in proportion to their length than in any other Atriplex of this group and the 

 seeds are considerably larger. 



ECOLOGY AND USES. 



Atriplex obovata is similar to A. nuttalli in ecological behavior, but it is less adaptable, 

 and hence is more restricted in range and habitat. It is taller and looser in growth and 

 in consequence is usually not a mound-former. It sometimes makes a pure consocies on 

 alkaline flats, but is more often associated with Sarcobaius, Suaeda, or Sporobolus airoides, 

 and such annuals as A. powelli, A. argentea, and Salsola. 



This species has much the same grazing value as nuttalli, but is eaten less because it 

 grows in a region where grass is more abundant. 



38. ATRIPLEX NUTTALLI Watson, Proc. Am. Acad. 9:116, 1874.' Plate 51. 



MOUNDSCALE. 



Erect or slightly spreading subshrub, woody at the base, but the erect or ascending 

 stems mainly herbaceous, 2 to 5 dm. high; branches rigid, not angled, gray or whitish with 



' The reasons for retaining this name instead of A. gardneri, as called for by the botanical codes, are stated under minor 

 variation 18 (p. 327). 



