28 BOTANICAL INFORMATION. 



num 661, Arenaria 26, Anthemidea 6, Apargia ? 40, Cantua? 

 25 and 42, Pentstemon 154, Lircwm 169, (Enothera 175 and 

 176, Crepis 179, Diplopappus pinnatifidus, Erysimum asperum, 

 (Enothera coronopifolia, Plantago gnaphaloides, Solidago, 

 Stenactis, Antennaria and other more common plants. 

 Orobanche fasciculata, springing from the roots of Artemisia 

 frigida, is here very abundant. 



Of rare plants, growing in peculiar localities : Bartonia 

 365, from the arid slopes of the high plain to the Platte 

 Valley ; Aster ea 277, near Fort Laramie ; Cyperoidea 54, 

 with a Psoralea 169, which seems distinct from P. esculenta 

 and probably is P. hypogeea, Nuttall ; of which I only found 

 one specimen.* 



3rd. Sub-region. — The sandy deserts alternate with the 

 largest tracts of saline deserts, and are based on the same 

 whitish, firm clay, which forms the crested surface of the 

 latter. The moving beds of sand, however, have an undu- 

 lated and ever-changing surface, as every where else. 



The deeper these drifting sands, the higher are the Arte' 

 misia bushes, the chief character of this sombre vegetation ; 

 they consist of two species only, A. cana and tridentaia- 

 The largest and oldest shrubs assume the shape of a small 

 tree about 8 feet high, with a short twisted trunk 4 or 6 

 inches diameter and very broad crown. Dispersed among 

 these bushes are one or two species of Chrysocoma, corymb- 

 branched greyish shrubs, not exceeding 2 feet in height, 

 especially n. 63. The few scattered grass plants are either 

 Eriocoma, Kcelera, or species of Stipa \ towards the Oases 

 occurs the tall Elymus n. 541. On elevation s^ the shrubby 

 Composite make room for Opuntia Missurica, which occupies 

 immense ranges, to the no small annoyance of the traveller, 



• The distribution of plants over the whole of the plains east of the 

 Rocky Mountains is in a narrow, somewhat semi-circular belt, from north 

 to west south-west ; so that the traveller may pass in one day through 

 one or two of such belts, never to see the same plants again in his journey. 

 This is most observable in the case of the rarest species, as Bartonia 

 omnia, Stanleya pinnatifida, Schrankia and others. 



