ROSACE AE (ROSK FAMILY) 497 



14. R. virginiana Mill. Stems often tall and stout (2-20 dm. high), with at 

 length stout and usually mure or less hooked prickles ; sltpuZes usually naked. 

 more or less dilated ; leaflets (mostly 7) dark green, rather thick, smooth and 

 often shining above ; flowers corymbose or solitary ; outer sepals frequently with 



1 or 2 small lobes. (R. lucida Ehrh.) Margins of swamps and rocky shores, 

 Nfd. and e. Que. to N. Y. and e. Pa. 



1;~>. R. humilis Marsh. Stems usually low (3-9 dm. high), slender, with 

 straight slender prickles (spreading or sometimes reflexed) ; stipules narrow, 

 rarely somewhat dilated ; leaflets as in the last, but usually thinner and duller; 

 flowers very often solitary ; outer sepals always more or less lobed. Mostly in 

 dry soil or on rocky slopes, N. S. to Fla., w. to Minn., Mo., Okla., and La. 



24. PRtTNUS [Tourn.] L. PLUM, CHERRY, ETC. 



Calyx 5-cleft ; the tube bell-shaped, urn-shaped, or tubular-obconical, decidu- 

 ous after flowering. Petals 5, spreading. Stamens 15-20. Pistil solitary, with 



2 pendulous ovules. Drupe fleshy, with a bony stone. Small trees or shrubs, 

 with mostly edible fruit. (The ancient Latin name.) CERASUS B. Juss. 

 AMVGDALDS L. 



a. Ovary glabrous ; stone smoothish or shallowly sculptured 5. 



b. Flowers racemose ; pedicels much shorter than the floriferous part 



of the rhachis. 



Leaves oblong, thlckish, crenate-serrulate, the teeth Incurved . 1. P. terotina. 

 Leaves mostly obovate, thin, sharply serrate ; teeth somewhat 



spreading 2. P. virginiana. 



b. Flowers umbellate or, if racemose, with pedicels exceeding the flo- 

 riferous part of the rhachis c. 

 c. Flowsrs small; petals mostly 4-6 mm. long d. 

 d. Leaves broad or, if narrow, serrulate practically to the base e. 

 e. Leaves lanceolate to oblong, ovate, or obovate f. 

 f. Petioles tomentose at least on the upper side. 

 Leaves lanceolate, attenuate. 



Petioles 15-33 mm. long 15. P. Jiortulana. 



Petioles 5-8 mm. long 4. P. alleyhanienitia. 



Leaves ovate- or obovate-oblong to elliptical. 

 Leaves obovate, thinnish, mostly cuneate at base, 1-2.5 

 cm. wide, somewhat doubly serrate ; pedicels 1-3 



in a fascicle 5. P. instititia. 



Leaves ovate- or obovate-oblong, thickish, rugose, 

 mostly obtuse at base, usually 3-4 cm. broad, sim- 

 ply serrate ; pedicels 2-6 in a "fascicle . . 6. P. maritima. 

 f. Petioles essentially glabrous. 



Teeth of the ovate-lanceolate mostly falcate-acuminate 



leaves unequal 8. P. pennsylranica. 



Teeth of the lance-elliptical acute or obtusish leaves equal 7. P. angutttifolia. 

 6. Leaves suborbicular, rounded or subcordate at base. 



Teeth of leaves fine, obtuse ; the sinuses glandular . . 8. P. Mahaleb. 

 Teeth of leaves coarser, bristle- tipped ; the sinuses not 



glandular 9. P. Gravesii. 



d. Leaves relatively narrow, spatulate-linear or -oblong, subentire 

 at the cuneate base. 



Erect shrub ; leaves spatnlate-oblong 10. P. euneata. 



Prostrate; leaves linear- or oblanceolate-spatulate . . .11. P.pumila. 

 C. Flowers large ; petals 8-16 mm. long. 



Teeth of leaves obtusish, some or all glandular. 

 Calyx-lobes entire or nearly so. 

 Inner scales of the flowering buds subherbaceous, ligulate, 



spreading 12. P. arium. 



Inner scales not very unlike the outer, subappressed . . 13. P. Cerasut. 

 Calyx-lobes conspicuously glandular-serrulate. 



Leaves thin, obovate ; petals 12-14 mm. long . . .14. P. nigra. 

 Leaves thickish, firm in texture ; petals about 8 mm. long . 15. P. hortulana. 

 Teeth of leaves acute or acuminate, bristle-tipped, not glandular 16. P. americana, 

 a. Ovary and fruit velvety-tomentose ; stone deeply sculptured and pitted 17. P. Pernica. 



1. PADUS [L.] Reichenb. Drupe small, globose, without bloom; the stone 

 turgid-ovate, marginless ; flowers in racemes terminating leafy branches, 

 therefore appearing after the leaves, late in spring. PADUS Moench. 



1. P. ser6tina Ehrh. (WILD BLACK or RDM C.) A large tree, with reddish- 

 brown branches, the inner bark aromatic; leaves oblong or lanceolate-oblong. 



GRAY'S MANUAL 32 



