ROSACE^E 555 



in pairs or rarely in 3-flowered clusters in the axils of the crowded leaves; calyx-tube slender, 

 '-j' long, thickly covered on the outer surface, like the short rounded lobes, with long 

 white hairs. Fruit: mature calyx-tube short-stalked, light red-brown, villose, 'deeply cleft 

 at apex, about |' long; akene nearly terete, covered with long white hairs; style I'-l^' in 

 length. 



A tree, 20-25 high, with a long straight trunk sometimes 6'-8' in diameter, erect rigid 

 branches forming a narrow open or irregular head, and slender bright red-brown lustrous 

 branchlets marked irregularly by large scattered pale lenticels, covered at first with a thick 

 coat of hoary tomentum, villose or pubescent for two or three years and ultimately ashy 



Fig. 511 



gray or gray tinged with red, the spur-like lateral branchlets much roughened by the ring- 

 like scars of fallen leaves. Bark about \' thick, divided by shallow fissures and broken 

 on the surface into small light red-brown scales. 



Distribution. In forests of Pines and Oaks usually at altitudes of about 5000, on the 

 dry ridges of the mountains of western Texas, and of southern New Mexico and Arizona; in 

 Arizona ranging northward to Oak Creek Canon, near Flagstaff, Coconino County (P. 

 Lowell); and southward over the mountains of northern Mexico. 



10. PRUNUS B. & H. Plum and Cherry 



Trees or shrubs, with bitter astringent properties, slender branchlets, marked by the 

 usually small elevated horizontal leaf-scars with 2 or 3 fibro-vascular bundle-scars, and 

 small scaly buds, their scales imbricated in many rows, those of the inner rows accrescent 

 and often colored. Leaves 'con volute or conduplicate in the bud, alternate, simple, usually 

 serrate, petiolate, deciduous or persistent; stipules free from the petiole, usually lanceolate 

 and glandular, often minute, early deciduous. Flowers in axillary umbels or corymbs, or 

 in terminal or axillary racemes, appearing from separate buds before, with, or later than the 

 leaves, or on leafy branches; calyx 5-lobed, the lobes imbricated in the bud; disk thin, ad- 

 nate to the calyx-tube, glandular, often colored; petals 5, white, deciduous; stamens usually 

 15-20, inserted with the petals in 3 rows, those of the outer row 10, opposite the petals, 

 those of the next row alternate w r ith them and with those of the inner row, sometimes 30 in 

 3 rows; filaments filiform, free, incurved in the bud; anthers oval, attached on the back; 

 ovary inserted in the bottom of the calyx-tube, 1-celled; style terminal, dilated at apex into 

 a truncate stigma; ovules 2, suspended; raphe ventral; the micropyle superior. Fruit a 1- 

 seeded drupe; flesh thick and pulpy or dry and coriaceous; stone bony, smooth, rugose, or 



