310 ERICACEAE 



name Uva-ursi, Latin, also meaning- bear and berry, was the original generic name, but 

 the International Rules do not permit the use of two separate words for generic names.] 



A genus of about 40 species; one of these, A. Uva-ursi (L.) Spreng., is circumboreal, the others inhabit west- 

 ern North America, Mexico and Central America, with the great majority in the Pacific States. Type species, 

 Arbutus Uva-ursi L. 



Fruit laterally compressed, small, with scanty glandular pulp, splitting open and falling early, nutlets thin- 

 walled; corolla 3-5 mm. long; leaves less than 25 mm. long. {Schisococcus) 

 Flowers 4-merous; leaves thin, cartilaginous, revolute on the margins. 1. A. Nummularia. 



Flowers 5-merous. 



Leaves bright green; older branches smooth and polished. 2. A. myrtifolia. 



Leaves pale green; older branches with shreddy bark. 3. A. nissenana. 



Fruit globose or depressed, rarely ellipsoid, not falling early and splitting. 



Pericarp with granular pulp; nutlets all separable or irregularly coalescent, or rarely (,A. Parryana) united 

 into a solid stone. 

 Leaves rounded at apex, not mucronate, bright green; fruit bright red, insipid; prostrate shrub. 



4. A. Uva-ursi. 



Leaves acute to rounded and mucronate or mucronulate at apex; fruit brown, acid. 



Low procumbent or prostrate shrubs, the lower branches rooting; corolla 4-5 mm. long. 

 Leaves broadest toward the apex. 



Prostrate glabrous montane species. S. A. nevadensis. 



Low coastal shrub with tomentose foliage and branches. 6. A. fumila. 



Leaves mostly broadest toward the base; coastal species. 

 Racemes few, generally simple. 



Shrub forming a mound-like mass S-10 dm. high; fruit shining, 4 mm. broad. 



7. A. Hookert. 



Shrub procumbent; fruit dull, 8 mm. broad. 8. A. franciscana. 



Racemes many, the terminal ones compound. 9. A. densiflora. 



Erect shrubs (sometimes the lower branches spreading and rooting in A. patula). 



Bracts shorter than the pedicels, mostly triangular or triangular-subulate, not foliaceous. 

 Pedicels glabrous or rarely puberulent. 



Branches of the racemes very slender, the flower-bearing portion not thickened; 

 corolla 5 mm. long (rarely 6 mm. in A. Stanfordiana) ; leaves bright shiny 

 green. 

 Branchlets glabrous. 10. A. Stanfordiana. 



Branchlets glandular-hispidulous. 11. A. hispidula. 



Branches of the racemes stoutish, the flower-bearing portion usually thickened; corolla 

 6-8 mm. long. 

 Leaves bright green. 



Young twigs and branches of the inflorescence glabrous or glandular not 

 tomentulose. 

 Ovary and fruit glabrous; twigs and branches of inflorescence resinous- 

 glandular or sparsely glandular-pubescent. 



12. A. patula. 



Ovary and fruit glandular; twigs and branches of inflorescence glabrous. 



14. A. elegans. 



Young twigs and branches of the inflorescence cinereous-tomentulose. 



Fruit ellipsoid-globose; nutlets united into a solid stone, prominently 

 ribbed and rugose. 13. A. Parryana. 



Fruit depressed-globose; nutlets irregularly separable. 



Leaves mostly over 20 mm. or more wide. 



15. A. Mamanita. 



Leaves seldom over 15 mm. wide; inflorescence short, usually of a 

 single raceme or rarely two. 

 Plants not sprouting from the base and therefore fire-killed; 

 bark exfoliating, smooth. 16. A. pungens. 



Plants sprouting from the root crown, not fire-killed; pedicels 

 puberulent; bark persisting and becoming shreddy. 



17. A. rudis. 



Leaves pale green; twigs and inflorescence glabrous or obscurely puberulent; 

 fruit 12-13 mm. broad. I?. A. mcwukka. 



Pedicels villous, usually glandular. 



Leaves bright shiny green, glabrous or nearly so; pedicels sparingly long-hairy. 



19. A. tnsularis. 



Leaves very pale ashy-green, glabrous or glandular-pubescent; pedicels densely glandu- 

 lar-pubescent. 

 Bracts short, triangular, persistent; fruit depressed-globose; nutlets separating. 



Herbage glabrous except for the glandular-puberulent pedicels. 



20. A. viscid a. 



Herbage at least the branchlets and inflorescence glandular-puberulent as 

 well as the pedicels. 21. A. mariposa. 



Bracts linear-lanceolate, about half as long as the pedicels, thin and mostly early 

 deciduous; fruit ovoid, pubescent; nutlets coalescing. 



22. A. drupacea. 



Bracts of the inflorescence usually foliaceous, about as long or longer than the pedicels, the 

 upper ones sometimes reduced and lanceolate-subulate. 

 Plants not stump-sprouting, and therefore fire-killed. 

 Leaves distinctly petiolate. 



Bark not exfoliating, but persistent and becoming shreddy. 



23. A. morroensts. 



