l-iii.h Mam \i 



1. Ptelea trifoliata 1>. Hoptrcc. A >linil) or small 

 tree with sunken superposed axillary buds covered by the 

 petiole base. Bark and flowers with a disagreeable odor. 

 Wood light brown, heavy, and hard. In woods. Conn, to 

 Fla., Ont., Minn., Kan., and Mexico. 



Siiiiontbaccar. Ailanthus Family. 



19. Ailanthus Desf. Ailanthus. 



Large trees with alternate, pinnately compound, large 

 leaves having green glands on the under side of the teeth at 

 the base of the leaflets. 



Branches robust with large brow^n pith; flowers diecious; 

 the 5 samaras linear or oblong, usually twisted. 



1. Ailanthus glandulosa Uesf. Tfee-of-heaven. A 

 large tree of rapid growth with thick branches and smooth 

 bark. Leaves ill-scented; leaflets with green glands under 

 the lobes or teeth. Autumn leaves pure yellow. Wood hard 

 and useful. Sprouts freely from the roots and is easily 

 propagated from root cuttings. A pest in pastures in some 

 states ; cows will not eat grass near the young shoots. Water 

 contaminated by the leaves is poisonous. Naturalized from 

 China. Ont. to Mass., Va., and Kan. 



Order, Malvales. 

 Tiliaceae. Linden Family. 



20. Tilia (Tourn.) L. Linden. 



Trees with 2-ranked, simple palmatcly veined, ino(|ui- 

 lateral, serrate or dentate leaves and solid pith. 



Flow^ers bisporangiate, pentamerous, stamens numerous : 

 dry drupaceous fruit in cymose clusters, the peduncle sub- 

 tended by a broad membranous bract. 



L Leaves glabrous or nearly so on both sides, except on 



the veins and in their axils. 2. 

 1. Leaves glabrous above, pubescent beneath. T. 



pubescens. 



1. Leaves glabrous above, silvery-white lieneath. T. 



hetcrophylla. 



2. Petals with scales at the base; inflorescence without 



bracts ; leaves comparatively large ; native. T. 

 aniericana. 



