RYDBERG: PHYTOGEOGRAPHICAL NOTES 325 
K. HOG-BACKS AND DRY RIDGES 
The flora of the hog backs in the Montane Zone, especially in 
its upper part, resembles that of the Subalpine Zone; in the lower 
regions there are many of the species of the dry plains added. Be- 
sides these there are a few restricted to the Montane Zone; nearly 
all of these are endemics. The flora consist of the following: 
I. EASTERN OR TRANSCONTINENTAL 
Juniperus sibirica Bouteloua gracilis 
Carex praticola Koeleria gracilis 
Carex stenophylla Poa crocata 
Calamagrostis purpurascens 
2. WESTERN 
Lewisia rediviva Sedum stenosepalum 
Oreobroma pygmaea Petrophytum caespitosum 
Oreobroma nevadensis Leptodactylon purgens 
Draba lutea 
3. ENDEMIC 
Lesquerella alpina Chrysopsis pumila 
Eriogonum (6 species) f Townsendia strigosat 
Physaria vitulifera _ Townsendia montanat 
Physaria acutifolia Erigeron ursinus 
Trifolium nanum Antennaria rosulatat 
Trifolium dasyphyllumt Tetraneuris lanigerat 
Kentrophyta aculeata Tetraneuris brevifolia 
Kentrophyta Wolfiit Senecio Purshianus 
Aragallus minor Senecio Fendlertt 
Phlox depressa Senecio werneriaefoliust 
Phlox Kelseyi 
SAND HILLS AND SAND-HILL DRAWS 
While the best developed sand and sand-hill draws are found 
in the region of the Great Plains east of the Rockies, and in the 
desert plains of the Great Basin west of the same; they are found 
also in the Submontane and Montane Zones. In the latter the 
sand-draws are found mostly in the bottoms of the canyons and the 
