EHAMNACEAE 239 



RHAMNACEAE 



Trees or shrubs, rarely herbs, sometimes climbing and spiny. 

 Leaves simple, alternate, rarely opposite. Flowers perfect or polygamous, 

 regular, perigynous, small, greenish or yellow, mostly in cymes. Sepals 

 5, rarely 4; petals 5 (4) alternate with the sepals; stamens opposite, and 

 the same number as the petals. Disk lining the calyx tube. Ovary 

 superior or inferior, 2-4 celled, usually 1 ovule in each cell; styles 2-4, 

 more or less connate. Fruit a drupe or a capsule or a winged nut. 



About 46 genera and 350 species widely distributed throughout the 

 world. The simple, 3 nerved leaves, perigynous flowers with the stamens 

 opposite the petals, are characteristic of this family. The genera treated 

 in this work are the only arborescent ones in China. 



KEY TO GENERA 



I. Leaves pinnately veined; ovary superior, 3-4 celled ; style 3-4 cleft; 

 fruit a drupe, free from the calyx, enclosing 3-4 stones. .Rhamnus. 

 II. Leaves 3 nerved at the base. 



A. Ovary free from the disk lining the calyx tubes. 



1. Fruit winged, dry and leatliery Palivrus. 



2. Fruit a fleshy, usually edible drupe Ziziphiw. 



B. Ovary adherent to tlie disk lining the calyx tube; fruit the size 



of a pea, 3-eelled,i 3-seoded, on a fleshy edible peduncle 



Hoxenia. 



RHAMNUS 



Shrubs or trees. Leaves serrate, alternate or subopposite, pinnately 

 veined, stipules mostly deciduous. Flowers small, perfect or dioecious in 

 racemes, cymes or panicles. Calyx 4-5 toothed; petals 4-5, clawed, 

 emarginate, or absent ; petals and stamens inserted on the edge of the disk 

 lining the receptacle. Ovary superior, 3-4 celled ; style 3-4 cleft. Fruit 

 a drupe, berry-like, enclosing 3-4 nutlet-like stones. 



About 90 species in the temperate nnd warm regions of the world. 

 The fruits and bark of several species, particularly that of Rhawnus 

 cathartica, widely distributed over Europe & N. Asia, contain a bitter, 



