ROSACES 509 



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 on the dry ridges of the mountains 

 of southern Arizona and New Mexico, and of western Texas, usually at elevations of 

 about 5000 above the sea, and southward over the mountains of northern Mexico. 



9. 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 conduplicate or convolute in the bud, alter- 

 nate, 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, adnate to the calyx-tube, gland- 

 ular, 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 with them and witli 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 the 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 pitted, compressed, indehiscent. Seed filling the cavity 

 of the nut, suspended; seed-coat thin, meinbranaceous, pale brown; cotyledons thick 

 and fleshy; radicle superior. 



Prunus with about one hundred and twenty species is generally distributed over 

 the temperate region of the northern hemisphere, and is abundant in North Amer- 

 ica, eastern Asia, western and central Asia and central Europe, ranging southward 

 in the New World into tropical America, and to southern Asia in the Old World. 

 Of the twenty-five or thirty species which occur in the United States, eighteen are 



