JVolJ GRAY AND HOOKER ON THE ROCKY MOUNTAIN FLORA. 23 



dance along the dry valleys, often accompanied by Tetradymia canescens ; 

 but upon tlie gravelly foot-liills the smaller Bigelovia Douglasii is much 

 more frequent." 



One or two names are changed in copying so' as to conform to the 

 more recent nomenclature. Eurotia lanata, though it happens not to 

 come into the above extract, is among the commonest of these plants, 

 and is one of the widest in range. Some Astragali, various JEriogona and 

 Gilice, also several FhaceUw and (Enotliercv, would be next in promi- 

 nence, the Eriogona much the most so. But the peculiarity of the 

 basin flora lies as much in the absence of other genera which charac- 

 terize adjacent districts as in the ubiquity of those which have been 

 mentioned. 



The genera peculiar, or nearly so, to the Great Basin proper and its 

 borders are chiefly — 



Physaria, a genus which was confounded on mere habit with Vesicaria, 

 belonging to the foot-hills rather than to the valleys, the principal species 

 extending around the whole limits of the region, a peculiar one at the 

 north and another at the south. 



Flatyspermiim, Hook., a little Cruciferous • annual of the western 

 border. 



Purshia, DC, a Eosaceous shrub, already mentioned. 



Tricardia and Conanthus, of S. Watson, Hydrophyllaceous herbs, the 

 latter close to Narna, the former a peculiar genus. 



Oryctes, Watson, a rather obscure Solanaceous herb of Western 

 ]!^evada. 



Nitrophila, Watson, an Amarantaceous herb of alkaline soil. 



Grayia, Hook., a Chenopodiaceous undershrub, already enumerated as 

 one of the most characteristic of the desert plants. {Sarcotatus would 

 go with it, except that it crosses the Eocky Mountains and abounds on 

 the upper waters of the Missouri, where it was first known, being the 

 Pulpy Thorn of Lewis and Clark.) 



Sermidium, Watson, a Nyctagineous perennial of the western edge of 

 the basin, intermediate between Bovgainmllea and Mirahilift. 



Oxytheca, Nutt., an offshoot of the great genus Eriogonmn. 



Tetradymia, DC, characteristic shrubbj' Senecioneous Compositoe of 

 two or three species, which slightly overpass the borders of the basin. 



Glyptopleura, Eaton, of two species, and Anisocoma, Gray, of one, de- 

 pressed Cichoraceous annuals or biennials. 



Chcctadelpha, Blcpharipappus, ixwiV lUgiopappus, each of a single species, 

 dkU^Psathyroteso^tv^o, southern in range, also Composite. 



There is, besides, Caulanthus of S. Watson, of two or three very char- 

 acteristic desert species, but some Califoruian, and the genus is (inly 

 artificially distinguished from Streptanthus, species of which rcarh tlie 

 Pacific coast on the one hand and IMissouri to Texas on the other. 



EremocJdoc, S. Watson, is a ])c'culiar genus of grasses, one six^cies pe- 

 culiar to the basin, another to the southeastern part of New i\Iexico. 



