SHRUBS NOT BECOMING ARBORESCENT. 
As far as known, the following list of shrubs comprises those that 
rarely, if ever, become arborescent; and the chief object in introducing 
them here is to complete, as far as possible, a full enumeration of the 
woody plants of the region. Plants woody only at the base have been 
mostly excluded. The annotations added may in some cases assist th< 
reader in recognizing the species. 
BERBERIDACEZ: Barberries. 
BERBERIS REPENS, Lindl. One foot or less in height: found throughout the Rocky 
Mountains, also on the Pacific coast; wood yellow. 
BERBERIS FENDLERI, Gray. Three to 6 feet: southern Colorado and southward ~ 
(westward to southern California). 
ZYGOPHYLLACE. 
CREOSOTE-BUSH, Larrea Mexicana, Moric.. Four to 10 feet: southern Colorado (to 
California; also in Texas): strang-scented ; foliage evergreen, dense; flowers 
yeilow ; fruit beaked. 
CELASTRACEZ: Staff-tree Family. 
PACHYSTIMA MyrsINITeEs, Raf. Low; Rocky Mountain region (northward and west- 
ward); foliage evergreen, forming dense clumps on timbered slopes. 
RHAMNACE.E: Buckthorn Family.* - 
BUCKTHORNS: 
Rhamnus alnifolia, L’Her. Two to4 feet: Wyoming (westward and eastward). 
Fruit black, berry-like; 2 to 4 seeds (nwtlets). 
Rhamnus Californica, Esch. Southwestern Colorado and New Mexico (to Cali- 
fornia and northward to the valley of the upper Sacramento River). As 
it oceurs in the Rocky Mountain region it is a low, spreading shrub (with 
young branches and under surface of the leaves white-woolly), but in Cali- 
fornia becoming a small tree 20 to 30 feet high: foliage evergreen; fruit 
black-purple, with scanty flesh and 2 to 3seeds. (Introduced among the 
shrubs, because the Rocky Mountain form is never arborescent. ) 
NEW JERSEY TEA: 
Ceanothus velutinus, Dougl. Two to 3 feet: Colorado, Utah (and northwest- 
ward): leaves thick, entire, resinous above; often velvety below. Var. 
levigatus, (Torr. & Gray) with leaves mostly smooth below, is commoner 
than the species. 
Ceanothus ovatus, Desf. Two to 3 feet: Colorado and Wyoming: leaves with 
small glandular teeth. 

a *Sce arboresceut species, page 168. 
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