The Buckthorns 



675 



IV. NORTHERN KARWINSKIA 



GENUS KARWINSKIA ZUCCARINI 



Species Karwinskia glandulosa Zuccarini 



SUALLY a shrub, this relative of the Buckthorns, which inhabits dry 

 soil from Texas to New Mexico, Lower CaHfomia, and northern 

 Mexico, sometimes forms a small tree about 7 meters high. It has 

 been confused with Karwinskia Humholdtiana Zuccarini, the type of 

 the genus, which occurs from southern Mexico to northern South America. The 

 generic name is in honor of the Ba- 

 varian Baron Karwinski von Kar- 

 win, who traveled in Brazil, and 

 died in 1855. 



The young twigs are finely and 

 sparingly hair}-, becoming smooth 

 and light brown, or sometimes per- 

 sistently hair}^ The leaves are op- 

 posite, rather short-stalked, oval or 

 oblong, entire-margined, strongly 

 pinnately veined, blunt or bluntish, 

 firm in texture, rounded at the 

 base, 3 to 7 cm. long, smooth on 

 both sides, dull, paler green on the 

 under than on the upper surface; 

 the leaf -stalks are 3 to 10 mm. 

 long. The small green perfect 

 flowers are in smooth axillary 

 stalked clusters, longer than the 

 leaf-stalks; the calyx is about 3 mm. broad, the 5 triangular pointed calyx-lobes 

 about as long as the calyx-tube; there are 5 small hooded petals; the 5 stamens are 

 a little longer than the petals; the ovar)^ is 2-celled with 2 ovules in each cavity; 

 the slender style is 2-lobed. The fruit is a nearly black round drupe, 10 to 12 

 mm. in diameter. 



Fig. 626. Northern Kanvinskia. 



V. THE BUCKTHORNS 



GENUS RHAMNUS [TOURNEFORT] LINN.^XTS 



OINIE 60 or 70 species of Rhamnus are known, widely distributed in 

 America, Europe, Asia, and Africa. Most of them are shrubs, but 

 a few form small trees. In North America, besides the 15 species 

 recognized as natives of the United States and Canada, and the 2 

 European ones that have become naturaUzed with us {Rhamnus cathartica and 



