510 TREES OF NORTH AMERICA 



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 Havor cor- 

 dials. '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. 



1. Flowers in sessile axillary umbels ; fruit often slightly 2-lobed by a ventral groove. 

 Plums. 



Leaves conduplicate in the bud. 



Fruit red or orange-colored, usually destitute of bloom, i'-l' in diameter. 

 Leaves oblong to obovate, broad, thick, and dull. 



Calyx-lobes glandular, glabrous on the inner surface ; stone compressed ; 

 petioles biglandular. 1. P. nigra (A). 



Calyx-lobes entire, pubescent on the inner surface ; stone turgid ; petioles usu- 

 ally without glands. 2. P. Americana (A, C, F). 

 Leaves ovate-lanceolate to lanceolate, narrow, thin, and lustrous ; petioles glandu- 

 lar ; stone turgid. 



Calyx-lobes pubescent ; leaves ovate-lanceolate. 3. P. hortulana (A, C). 

 Calyx-lobes glabrous ; leaves lanceolate to oblong-lanceolate. 



4. P. angustifolia (C). 

 Fruit blue, covered with a glaucous bloom, l'-^' in diameter ; leaves lanceolate to 

 oblong-ovate; petioles usually without glands. 5. P. Alleghaniensis (A). 



Leaves convolute in the bud. 



Fruit often 1' or more in diameter, red or yellow, nearly destitute of bloom; leaves 

 broadly ovate to orbicular ; petioles mostly without glands. 



6. P. subcordata (G). 

 Fniit i;' in diameter or less. 



Fruit dark blue or black, covered with a glaucous bloom ; leaves ovate-lanceolate 



to oblong ; petioles mostly without glands. 7. P. umbellata (C). 



Fruit yellow, red, blue, or black, covered with a glaucous bloom ; leaves oblong 



to obovate ; petioles conspicuously biglandular. 8. P. tarda (C). 



2. Flowers in axillary umbels or corymbs ; fruit globose, ^' in diameter or less, bright 

 red and lustrous ; leaves conduplicate in the bud. Bird Cherries. 



Leaves usually oblong-lanceolate, acuminate or rarely acute. 



9. P. Pennsylvanica (A, B, F). 

 Leaves usually oblong-obovate and obtuse. 10. P. emarginata (B, F, G). 



3. Flowers in terminal racemes on leafy branches of the year ; fruit globose ; leaves con- 

 duplicate in the bud. Wild Cherries. 



Calyx-lobes deciduous from the fruit ; leaves broadly oval or oblong-obovate, usually 

 abruptly acuminate. 11. P. demissa (B, F, G). 



Calyx-lobes persistent on the fruit. 



Leaves oblong or lanceolate-oblong, usually narrowly cuneate. 



12. P. serotina (A, C, E, H). 

 Leaves ovate-oblong or elliptic. 13. P. Alabamensis (C). 



Leaves obovate, oval or elliptic, clothed below with pale or rufous matted hairs. 



14. P. australis (C). 



4. Flowers racemose in the axils of persistent leaves of the previous year ; fruit globose or 

 slightly 2-lobed ; leaves conduplicate in the bud. Cherry Laurels. 



Calyx-lobes rounded, with undulate margins ; stone broadly ovate, cylindrical ; leaves 

 entire or rarely remotely spinulose-serrate. 15. P. Caroliniana (C). 



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