ROSACEAE 163 



ROSACEAE 



Leaves usually alternate, dentate, lobed or divided, usually with 

 iistipules. Flowers generally regular. Stamens distinct, indefinite.' Car- 

 pels one to many, distinct or united with the calyx tube. Ovules usually 

 2 in each cell. Seeds exalbuminous. 



A family consisting of 90 genera and about 1,500 species, most 

 abundant in the temperate region, but widely distributed throughout the 

 world. Many genera are cultivated for ornament and for their edible 

 fruits. 



In a work of limited scope only the more important arborescent 

 genera can be dealt with. 



KEY TO GENERA 



A. Fruit a pome inclosing bony or papery carpels. 



I. Carpels bony at maturity, flowers in cymose-corymbs ; ovary 

 1-5 celled; ovules 1 in each cell or if 2, 1 sessile and fertile, 

 the other Stalked and sterile; deciduous, usually thorny shrubs 

 or trees; fruit with 1-5 bony seeds Crataegus. 



IT. Carpels with leathery or papery walls at maturity. 



a. Carpels as many as the styles. 



(a) Carpels partly free. 



1. Flowers in simple cymes on short lateral spurs; 

 ovary 3-5 celled, styles more or less connate 

 below ; winter buds small Malus. 



2. Flowers in compound cymes ; ovary usually 3 

 (2-4) celled; style distinct; leaves mostly pin- 

 nately compound ; winter buds large Sorbus. 



_(b) Carpels wholly connate ; styles 5, distinct; fruit large, 

 pear shaped, yellow; evergreen tree Eriobotrya. 



■ b. Cells of the ovary twice as many as the styles, flowers in 

 racemes; ovary inferior or partly so; styles 2-5; more or 

 less connate below; fruit subglobose; leaves simple de- 

 ciduous Amelanchier. 



B. Fruit a 1-seeded drupe ,* ovary superior, not inclosed in calyx tube at 

 maturity, 1 celled; style terminal; leaves simple, deciduous . .Primus. 



