524 FLORA. 



Flowers 15-30 mm. broad ; trees. 



Leaves glabrous ; pedicels short ; fruit sour. 14. p. Cerasus. 



Leaves pubescent beneath, at least on veins; pedicels long; fruit sweet. 



15. P. Avium. 

 1 1 Inflorescence more or less corymbose : leaves shining. 



1 6. P. Pennsylvania^, 

 * * Flowers corymbose, terminating twigs of the season. 17. P. Mahaleb. 



* * * Flowers racemed, terminating branches of the season. 



Fruit red to purple, astringent ; leaves obovate or oval. 18. P. Virginiana. 



Fruit purple or purplish-black, sweet or bitter. 



Leaves oval or obovate ; shrub or small tree. 19. P, demissa. 



Leaves oval-lanceolate to ovate ; large tree. 20. P. serotina. 



1. Prunus Americana Marsh. WILD YELLOW OR RED PLUM. d. F. f. 2007.) 

 A shrub or small tree; branches more or less thorny; bark thick. Leaves ovate or 

 obovate, nearly or quite glabrous when mature, usually pubescent when young, 

 sharply and often doubly serrate, rounded at the base, slender-petioled; petioles 

 usually glandless; flowers 'white, 1.5-2.5 cm. broad; pedicels 1-2 cm. long; drupe 

 1.8-2.5 cm. in diameter, the skin tough, bloom little or none, t the stone somewhat 

 flattened, its ventral edge acute or margined, the dorsal faintly grooved. N. Y. to 

 Mont., Fla. and Colo. April-May. Fruit ripe Aug. -Oct. 



2. Prunus nigra Ait. CANADA PLUM. HORSE PLUM. (I. F. f. 2008.) A 

 tree, 6-10 m. high ; bark thin. Leaves oval, ovate or obovate, long- acuminate, 

 pubescent when young, crenulate- serrate ; petioles stout, 1-2.5 cm - l n g> bearing 

 I or 2 red glands near the blade ; flowers 2.5-3 cm - broad; pedicels 1-2 cm. long, 

 glabrous; calyx-lobes glandular-serrate; drupe oval, 2.5-3 cm. long, orange-red, 

 thick-skinned, bloom little or none, the flesh adherent to the oval compressed stone, 

 which is sharply ridged on the ventral edge, somewhat grooved on the dorsal. 

 Newf. to Man., Mass, and Wis. May. Fruit Aug. Petals pink in age. 



3. Prunus hortulana Bailey. WILD GOOSE PLUM. (I. F. f. 2009.) A small 

 tree, similar to the two preceding; branches spreading ; bark thin. Leaves ovate- 

 lanceolate to ovate, long-acuminate, closely glandular- serrate, 10-15 cm - l n g; 

 petioles not 2. 5 cm. long, usually bearing two glands near the blade; pedicels 1-2 

 cm, long ; calyx-lobes glandular-serrate; drupe subglobose or short-oval, bright 

 red, thin-skinned, bloom little or none, stone swollen, roughish, not margined. 111. 

 to Tenn., Kans. and Tex. April-May. 



Prunus hortul^na Mineri Bailey. Leaves dull, thick, irregularly coarsely serrulate, 

 conspicuously veiny beneath ; stone nearly smooth ; leaves varying to oblanceolate. 111. 

 to Tenn. and Mo. 



4. Prunus angustifolia Michx. CHICK AS AW PLUM. HOG PLUM. (I. F. f. 

 2010.) A small tree, the branches somewhat thorny. Leaves acute, serrulate, 

 often rounded at the base, 7-13 cm. long; flowers smaller than those of the preceding, 

 in lateral umbels, expanding before the leaves; drupe red, globose, 12-18 mm. in 

 diameter, nearly destitute of bloom, its stone ovoid, hardly flattened, both edges 

 rounded, one of them slightly grooved. In dry soil, N. J. to Fla., west to the 

 Rocky Mts. April. Fruit ripe May-July. 



5. Prunus Watsoni Sargent. WATSON'S PLUM. SAND PLUM. (I. F. f. 

 2011.) A shrub, 2-3.5 m - high' somewhat spiny. Leaves firm, acute or acumi- 

 nate at the apex, finely crenulate-serrulate, 2-5 cm. long, shining above, the peti- 

 oles about i cm. long; flowers 10-12 mm. broad; pedicels 8-12 mm. long, red, 

 glabrous; fruit globose or somewhat elongated, about 18 mm. in diameter, orange- 

 red, without a bloom, the flesh yellow ; stone oval, pitted, mostly rounded on both 

 margins, abruptly flattened at the summit. Sandy soil, Neb. to Ark. April-May. 



6. Prunus Alleghaniensis Porter. PORTER'S PLUM. (I. F. f. 2012.) A 

 low, straggling shrub or small tree; seldom thorny. Leaves acute or acuminate, 

 finely serrate, rounded at the base, pubescent when young; flowers about 14 mm. 

 broad; drupe globose-ovoid, about i cm. in greatest diameter, with a conspicuous 

 bloom; pulp pleasantly acid; stone slightly flattened, a shallow groove on one 

 margin, a slight expansion on the other. E. Conn.; Huntingdon Co., across the 

 Allegheny Mts. to Clearfield Co., Pa. April. 



7. Prunus raaritima Wang. BEACH PLUM. (I. F. f. 2013.) A much- 

 branched shrub, 0.3-2 m. high, not thorny. Leaves oval, ovate or obovate, finely 



