76 KOSACE^E. (ROSE FAMILY.) 



18. Ivesia. Petals yellow, with claws, or spatulate. Stamens 20; filaments filiform. 



Carpels 1 to 15, on a dry villous receptacle. Leaves pinnate ; leaflets cleft or parted, 

 often small and very numerous and closely imbricated. 



19. Chamserhodos. Petals white, obovate. Stamens 5 ; filaments short, subulate. 



Carpels 5 to 10, on a dry villous receptacle. Leaves many-cleft ; the segments 

 linear. 



Tribe IV. POTERIE.^2. Carpels 1 to 3, in fruit akenes, completely enclosed in the 

 dry and firm calyx-tube, the throat of which is constricted or sometimes nearly closed. 

 Seed suspended. Ours are herbs with pinnate leaves and solitary ovule. 



20. Agrimoiiia. Calyx turbinate, surrounded by a margin of hooked prickles. Petals 



yellow. Stamens 5 to 12. Flowers in long racemes. 



21. Poterium. Calyx-lobes 4, imbricate, deciduous, petaloid ; the tube 4-angled, naked. 



Petals none. Flowers in dense heads. 



Tribe V. ROSE^E. Carpels many, in fruit bony akenes, enclosed and concealed in the 

 globose or urn-shaped fleshy calyx-tube, which resembles a pome. Petals conspicuous. 

 Stamens numerous. 



22. Rosa. Erect shrubs, with pinnate leaves. 



SUBORDER III. POITIE^E. 



Carpels 2 to 5, enclosed in and mostly adnate to the fleshy calyx-tube, 

 in fruit becoming a pome. A pair of ovules in each carpel. Styles 

 often united below. Trees or shrubs, with stipules free from the petiole 

 or nearly so. 



23. Cratsegus. Ovary 2 to 5-celled ; the fruit drupaceous, of 2 to 5 bony 1-seeded stones, 



either separable or united into one. Branches usually thorny. 



24. Pyrus. Ovary 2 to 5-celled ; the fruit a proper pome, with papery or cartilaginous and 



undivided 2-seeded cells or carpels. 



25. Amelanchier. Ovary 5-celled ; the cells 2-ovuled and 2-seeded, but in fruit each 



divided into two by a partition from the back. Styles 3 to 5. Otherwise like Pyrus. 



26. Peraphyllum. Ovary usually 2- (incompletely 4-) celled. Styles 2. Otherwise like 



Amelanchier. 



1. P RUN US, Tourn. PLUM, CHERRY, &c. 



Calyx 5-cleft. Petals 5, spreading. Stamens 15 to 25, inserted with the 

 petals. Leaves simple, usually serrulate: flowers white, fascicled in the 

 axils, or in terminal racemes. 



* Flowers in umbel- or corymb-like dusters from lateral scaly buds in early spring, 

 preceding or coe'taneous with the leaves. 



1. P. Americana, Marshall. (WILD YELLOW or RED PLUM). Tree 

 thorny, 8 to 20 feet high : leaves ovate, or somewhat ohovate, conspicuously 

 pointed, coarsely or doubly serrate, very veiny, glabrous when mature : fruit nearly 

 destitute of bloom, roundish ovnl, yellow, orange, or red; the stone turgid, more 

 or less acute on both margins , pleasant-tasted, but with a tough and sour skin. 

 Colorado. Very common throughout the East. 



2. P. Chicasa, Michx. (CHICKASAW PLUM.) Stem scarcely thorny: 

 leaves nearly lanceolate, finely serrulate, glabrous: fruit nearly destitute of 

 bloom, globular, red ; the stone ovoid, almost as thick as wide, rounded at both 

 sutures^ one of them minutely grooved. Perhaps native only west of the Mis- 

 sissippi from Arkansas southward, but introduced eastward, and westward to 

 Colorado. 



