100 



THE WALNUT FAMILY— JUGLANDACEAE. 



This family comprises about 6 genera with 35 species of trees am 

 shrubs found chiefly in the warmer portion of the north temperate 

 zone. Two genera with about 19 species are native to North Amer 

 ica. Both of these genera, Juglans and Oarya, have representativej 

 in Pennsylvania. The former genus has 2 species and the latter 

 species native to the State. In addition to the existing species 

 great number of fpssil species have been referred to this family 

 Thirty fossil species belonging to the genus Juglans and 10 species 

 belonging to the genus Carya have been described. 



This is one of the most important families of trees native to Penn 

 sylvania. Both the Hickories and the Walnuts yield very valuabli 

 wood. The wood of the Walnuts is esteemed especially for cabine 

 work and that of the Hickories on account of its strength and flexi 

 bility. The bark and husks of the Walnuts are used sometimes as 

 dyestuff. The fruit of both genera is edible. 



The staminate and pistillate flowers are separate but borne oi 

 the same tree and usually in the same branch. The staminate flow 

 ers are in long drooping aments while the pistillate appear as bud 

 and occur in small few-flowered clusters. The leaves of both generi 

 are compound and alternate. The fruit is a nut. The nut of th 

 Walnuts is sculptured and covered with a fleshy, indehiscent, pulp; 

 husk while the nut of the Hickories is not sculptured but covere 

 with a dehiscent husk. 



KEY TO THE GENERA. 



1. Pith of twigs chambered; nuts sculptured or rugose with indehiscent husk; staminate 



catkins thick, compact, usually sessile and solitary; wood diffuse-porous, Juglans 1^ 



1. Pith of twigs continuous; nuts smooth or ridged with dehiscent husk; staminate 

 catkins slender, loose, long-stalked, in 3s; wood ring-porous Carya 



