742 



TREES OF NORTH AMERICA 



loose dull usually pale tomentum, 1'--^' long and ^'-f ' wide, falling irregularly dur- 

 ing the winter; their petioles short, slender, and hairy. FloTvers opening in summer 

 on hairy pedicels ^' in length, in 16-18-llowered fascicles; calyx ovate, with ovate 

 rounded lobes coated on the outer surface with pale or ferrugineous tomentum and 

 rather shorter than the tube of the corolla; staminodia ovate, acute, remotely and 

 slightly denticulate, as long as the corolla-lobes furnished with small ovate acute 

 appendages; ovary hirsute, abruptly contracted into a slender elongated style. Fruit 

 on slender drooping stalks ripening and falling in the autumn, oblong or slightly 

 obovate, ^' long; with thick flesh; seed oblong, rounded at the apex, about ^' in 

 length. 



A tree, sometimes 50-60 high, with a tall straight trunk occasionally 3 in diam- 

 eter, short thick tough rigid branches forming a narrow oblong round-topped head, 

 unarmed, or armed with stout rigid straight slightly curved spines frequently devel- 

 oping into spinescent leafy lateral branchlets, and slender often somewhat zigzag 

 branchlets coated with thick rufous or pale tomentum when they first appear, be- 

 coming in their first winter red-brown to ashy gray and glabrous or nearly so and 



marked by occasional minute lenticels and by small semiorbicular leaf-scars dis- 

 playing 2 clusters of fibro-vascular bundle-scars; much smaller in the region east of 

 the Mississippi River, and there rarely more than 20 tall. Winter-buds obtuse, |' 

 long, covered with broadly obovate rusty tomentose scales. Bark of the trunk ^' 

 thick, dark gray-brown and usually divided into narrow ridges broken into thick 

 appressed scales. Wood heavy, rather soft, not strong, close-grained, light brown 

 or yellow, with thick lighter colored sapwood; producing in Texas considerable 

 quantities of clear viscid gum from the freshly cut wood. 



Distribution. Southern Georgia and northern Florida to the shores of Mobile 

 Bay, Alabama, and southern Illinois and southern Missouri through Arkansas and 

 Texas to the mountain slopes of Nuevo Leon; east of the Mississippi River usually 

 in dry rather sandy soil and nowhere common; abundant and of its largest size in 

 the river-bottoms of eastern Texas. In the region adjacent to the southern boundary 

 of the United States from western Texas and Nuevo Leon to Arizona a form (var. 

 rigida, Gray) occurs, with more rigid spinescent branches and with thick coriaceous 

 obovate to cuneate-oblanceolate leaves rather more than 1' long and ^' wide, and 

 covered at maturity on the lower surface with sparse pale tomentum, or nearly gla- 



