17. Leaves narrower; native. 



18. Leaves oblong-obovate; Montana and British Colum- 



bis to Arizona and New Mexico 



P. emarginata Bitter Cherry, p. 263. 



18. Leaves oblong-lanceolate; Newfoundland to British 

 Columbia, south to Georgia, Iowa, and Colorado . . . 



P. pensylvanica Pin Cherry, p. 263. 



14. Flowers 12 or more in elongated racemes. 



19. Leaves deciduous; flowers in terminal, usually leafy racemes. 

 20. Calyx deciduous from fruit; leaves oblong-oval to obo- 



vate, with spreading teeth; entire area 



P. virginiana Common Chokecherry, p. 261. 



20. Calyx persistent on fruit; leaves with incurved teeth. . . . 

 P. serotina, Black Cherry, p. 261. 



19. Leaves persistent; flowers in axillary, leafless racemes. 



21. Southeast; leaves entire or rarely with few small spiny 

 teeth. 



22. Leaves elliptic to ovate; Southern Florida 



P. myrtifolia Urb., Myrtle Laurelcherry 



22. Leaves oblong-lanceolate : North Carolinia to Texas. . 

 P. caroliniana Ait., Carolina Laurelcherry 



21. California. 



23. Leaves spiny toothed 



P. ilicifolia Dietr, Hollyleaf Cherry 



23. Leaves entire or minutely toothed 



P. lyonii Sarg, Catalina Cherry 



* * * 



Christmasberry 



Photinia arbutifolia Lindl. {Heteromeles arbutifolia Roem.) 



An evergreen shrub or small tree native to lower mountain 

 slopes in California and Lower California which is widely planted 

 as an ornamental because of its lustrous evergreen leaves and 

 clusters of red fruits which resemble those of mountain-ash. 

 This tree is characterized by alternate, simple, thick, glossy, 

 serrate, persistent leaves; small, white, perfect flowers in terminal 

 corymbs; and fruit a red, ovoid, clustered pome about Yi inch 

 long. 



Cliffrose. Quininebush 

 Cowania mexicana D. Don 



This shrub or small tree rarely 25 feet high is found on dry 

 slopes from Nevada to Colorado and south into Mexico. It 

 is characterized by odd, simple, alternate leaves, which are 

 3-5 lobed, Vi—Vi inch long, thick, dark green above and woolly 

 below, and tardily deciduous to persistent; perfect, regular, 

 solitary, showy flowers, which are pale yellow to white and about 

 one inch across; from which develop 5-12 achenes, each about 

 V4 inch long and tipped with a 2 inch white, hairy style. 



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