556 TREES OF NORTH AMERICA 



pitted, compressed, indehiscent. Seed filling the cavity of the nut, suspended; seed-coat 

 thin, membranaceous, pale brown; cotyledons thick and fleshy; radicle superior. 



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

 temperate regions of the northern hemisphere, and is abundant in North America, 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, twenty-two are arborescent in habit. Several of 

 the species bear fruits which are important articles of human food; many contain in the 

 seeds and leaves hydrocyanic acid, to which is due their peculiar odor, and the fruit of some 

 of the species is used to flavor cordials. The wood of Prunus is close-grained, solid, and 

 durable, and a few of the species are important timber-trees. 



Prunus is the classical name of the Plum-tree. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 



Flowers in sessile axillary umbels; fruit usually slightly 2-lobed by a ventral groove, gener- 

 ally more than \' in diameter, red to nearly black or yellow, often covered with a glau- 

 cous bloom. PRUNOPHORA. PLUMS. 

 Leaves convolute in the bud, their petioles usually without glands. 



Leaves broad-ovate to orbicular; fruit often 1' or more in diameter, red or yellow, 



nearly destitute of bloom. 1. P. subcordata (G). 



Leaves ovate-lanceolate to oblong or obovate; fruit \' in diameter or less, blue, nearly 



black, red or yellow, covered with a glaucous bloom. 2. P. umbellata (C). 



Leaves conduplicate in the bud. 



Leaves dull dark green, usually abruptly pointed at apex. 



Fruit red, rarely yellow, or blue in one form of 2 and 5; leaves oblong to obovate; 



stone of the fruit compressed. 

 Leaves crennate-serrate, their petioles biglandular; calyx-lobes glandular. 



3. P. nigra (A). 



Leaves sharply serrate with slender often apiculate teeth. 

 Leaves narrowed and usually cuneate at base. 



Leaves glabrous or villose on the midrib below; petioles and calyx-lobes usu- 

 ally without glands. 4. P. americana (A, C, F). 

 Leaves pubescent below; fruit covered with a thick glaucous bloom. 



Petioles eglandular or with a single gland near the apex; pedicel of the 

 flower glabrous; calyx-tube puberulous; stone of the fruit rounded at 

 base. 5. P. lanata (A, C). 



Petioles glandular near the apex with 1-3 prominent glands; pedicel of 

 the flower furnished near the apex, like the glabrous calyx-tube, with 

 long white hairs; stone of the fruit pointed at base. 



6. P. tenuifolia (C). 



Leaves usually broad and rounded at base, ovate to elliptic or obovate, con- 

 spicuously reticulate- venulose; petioles glandular. 7. P. mexicana (C). 

 Fruit purple, covered with a glaucous bloom; leaves lanceolate to oblong-ovate; peti- 

 oles and calyx-lobes without glands; stone of the fruit turgid. 



8. P. alleghaniensis (A). 



Leaves thin and lustrous, acute or acuminate, narrowed at base; petioles usually glan- 

 dular; fruit red or yellow, the stone turgid. 

 Calyx-lobes glandular. 



Leaves oblong-obovate to oblong-oval or rarely oblong-lanceolate. 



9. P. hortulana (A). 



Leaves elliptic to lanceolate. 10. P. Munsoniana (A, C). 



Calyx-lobes without glands; leaves lanceolate to oblong-lanceolate. 



11. P. angustifolia (A, C). 



