UOSACEAEl (ROSE FAMILY) 497 



// i4. R. virginiana Mill. Steins often tall and stout (2-20 dm. high), loith at 

 hngth stout and usually more 07' less hooked prickles ; s^ipu?es usually naked. 

 more or less dilated; leajlets (mostly 7) dark green, rather tliick, smooth and 

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



1 or 2 small lobes. {B. lucida Elirh.)^ Margins of swamps and rocky shores, 

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



lo. R. h^milis Marsh. Stems usually low (3-9 dm. high), slender, with 

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

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

 flowers very often solitary ; outer sepals always more or less lohed. — 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. 

 Amygdalus L. 



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



h. Flowers racemose ; pedicels mach shorter than the flonferous part 

 of the rhachis. 

 Leaves oblong, thickish, crenate-serrulate, the teeth incurved . 1. /*. seroiina. 

 Leaves mostly obovate, thin, sharply serrate; teeth somewhat 



spreading 2. P. mrginiana. 



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

 riferous part of the rhachis c. 

 V. Flowers small ; petals mostly 4-6 mm. long d. 

 d. Leaves broad or, if narrow, serrulate practically to the base 6. 

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

 /. Petioles tomentose at least on the upper side. 

 Leaves lanceolate, attenuate. 

 Petioles 15-33 mm. long . ... 15. P. hortula^ia. 



Petioles 5-8 mm. long .... . 4. i*. allegkanienHW. 



Leaves ovate- or obovate-oblong to elliptical. 

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

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



in a fascicle 5. P. inaUiiiia. 



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

 mostly obtuse at base, usually 8-4 cm. broad, sim- 

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

 f. Petioles essentially glabrous. 



Teeth of the ovate-lanceolate mostly falcate-acuminate 



leaves unequal S. P. pennsylvaiiica 



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

 1 e. Leaves suborbicular, rounded or subcordateat 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, subenth-e 

 at the cuneate base. 



Erect shrub ; leaves spatulate-oblong 10. P. cv/neata. 



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 bo. 

 Inner scales of the flowering buds subherbaceous, ligulate, 



spreading 12. P. avium. 



Inner scales not very unlike the outer, Bubappressed . . 13. P. C&raaua. 

 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. Persica. 



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

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

 therefore appearing after the leaves, late inspring. Padus MoeiTch. 



[^ 1. P. ser6tina Ehrh. (Wtlo Black or Rcm C.) A large tree, with reddish- 

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



gbay's manual — 32 



