FLOWERING PLANTS AND FERNS OF ARIZONA 411 



2. Flowers numerous, in elongate racemes; pedicels glabrous or puberulent; 

 leaf blades serrate or serrulate, the teeth not conspicuously glandular, 

 commonly appressed or incurved : Subgenus Padus (3) . 

 3. Calyx deciduous long before maturity of the fruit; leaf blades mostly 

 rounded or subcordate at base; petals about 5 mm. long. 



3. P. VIRGINIANA. 



3. Calyx persistent until maturity of the fruit; leaf blades mostly acute or 

 acutish at base; petals about 3 mm. long 4. P. virexs. 



1. Primus fasciculata (Torr.) A. Gray, Amer. Acad. Arts and Sci. 



Proc. 10: 70. 1874. 



Emplectocladus Jasciculatus Torr., PL Fremont. 10. 1853. 



Coconino County (bottom of the Grand Canyon), Mohave County 

 (many localities) and near Wickenburg (Maricopa County), 4,500 

 feet or lower, dry plains and slopes, often forming thickets, March. 

 Southern Utah, Arizona, and southern California. 



Desert-almond. Browsed by sheep and goats. 



2. Primus emarginata (Dougl.) Walp., Repert. Bot. 2: 9. 1843. 



Cerasus emarginata Dougl. ex Hook., Fl. Bor. Amer. 1: 169. 

 1830. 



Coconino County and Hualpai Mountain (Mohave County) to 

 Cochise and Pima Counties, 5,000 to 9,000 feet, mostly in pine forests, 

 April to June. Idaho to British Columbia, south to New Mexico, 

 Arizona, and California. 



Bitter cherry. In Arizona there occur both the typical form, with 

 leaf blades oval or obovate, mostly obtuse or rounded at apex, some- 

 times sparsely pubescent beneath; andvar. crenulata (Greene) Kearney 

 and Peebles {Cerasus crenulata Greene) with leaf blades elliptic or 

 oblanceolate, mostly acute or acutish at apex, commonly glabrous 

 beneath. The variety has been collected on the San Francisco Peaks 

 and Bill Williams Mountain (Coconino County) and in the Pinaleno 

 Mountains (Graham County). 



3. Prunus virginiana L., Sp. PI. 473. 1753. 



Apache, Navajo, and Coconino Counties, south to Greenlee and Gila 

 Counties, 4,500 to 8,000 feet, coniferous forests, April and May. 

 Canada to Georgia, New Mexico, Arizona, and California. 



Common chokecherry. The tree reaches a height of 7.5 m. (25 

 feet) and a trunk diameter of 20 cm. Represented in Arizona by var. 

 demissa (Nutt.) Torr. (Prunus demissa D. Dietr.), the western choke- 

 cherry, with the twigs and the lower surface of the leaves pubescent 

 when young, the mature fruit dark red; and by var. melanocarpa (A. 

 Nels.) Sarg. (Prunus melanocarpa Rydb.), the black western choke- 

 cherry, with the twigs and the lower surface of the leaves glabrous 

 or nearly so, the mature fruit nearly black. 



4. Prunus virens (Woot. and Standi.) Shreve, Carnegie Inst. Wash. 



Pub. 217: 43. 1915. 



Padus virens Woot. and Standi., Contrib. U. S. Natl. Her- 

 barium 16: 132. 1913. 



Apache County to Mohave County, south to Cochise, Santa Cruz, 

 and Pima Counties, 4,500 to 6,000 feet, common, usually along 

 streams, April and May. Western Texas to Arizona and northern 

 Mexico. 



