Trees of New lurk ><t(i{c 2U.j 



ULMACEAE 



Ulinus raeemosa Thomas [Ulnuis Thomasi Sarg.j 



Rock Elm, Cork Elm 



Habit — A tree usually oO-SU feet in height witii a trunk diameter of 2-3 

 feet, occasionally under optimum conditions 100 feet tall with a trunk 4-5 

 feet through. In the open the crown is narrowly oblong and round-topped, 

 consisting of numerous short, slender branches, those near the base droop- 

 ing and extending to within 6-8 feet of the ground. Bole continuous into 

 the crowni, under forest conditions sometimes free of branches for 40-60 

 feet. 



I<eaves — Alternate, oblong-oval to obovate, 2-2% inches long, %-l inch wide, 

 abruptly acuminate at the apex, rounded and inequilateral at the base, 

 coarsely doubly serrate, at maturity thick, firm, smooth, dark green and 

 lustrous above wiith prominent midrib and secondary veins, palo pubescent 

 beneath, borne on stout petioles about Vi of an inch long. 



Flowers — Perfect, long-pedicellate, appearing before the leaves during April 

 and early May in long-pedunculate, j)uberulous, 2-4-flowered racemose 

 cymes from separate flower-buds. Calyx campanulate, green, divided 

 nearly to the middle into 7-8 rounded, dark red lobes. Stamens as many 

 as the corolla lobes, exserted, with slender, pale gi-een filaments and purj)le 

 anthers. Pistil consisting of a compressed, pale-hairy, 2-celled ovary sur- 

 mounted by 2 green styles stigmatie along their inner margin. 



Fruit — A 1-seeded, oval to obovate-oblong, long-stalked, pale green samara, 

 about % of an inch long, pubescent, ciliate on the margin, ripening when 

 the leaves are about half grown. Wing broad, shallowly notched at the 

 apex of the fruit, obscurely veined, somewhat thickened and ciliate at the 

 border. 



"Winter characters — Twigs slender, lenticellate, glabrous and lustrous or 

 ])uberulous, light reddish brown, at length dark brown or ashy-gray and 

 often corky-ridged. Terminal bud absent. Leaf-buds inserted near the 

 end of the twig, ovate, sharply acute, about V^ of an inch long, the scales 

 chestnut-brown with ciliate margins. Flower-buds occasionally bearing 

 1-2 small leaves, similar but slightly larger than the leaf-buds, borne 

 below the leaf -buds on the twig. Mature bark thick, rough, grayish brown, 

 divided by deep fissures into broad, flat ridges, scaly at the surface. 



Habitat — Prefers dry stony uplands, especially limestone outcrops, but 

 thrives on heavier, poorly drained clay soils. 



Bange — Southern Quebec westward through southern Ontario, central Michi- 

 gan and Wisconsin, to Nebraska, southward to Tennessee and Missouri. 

 Zones B and C. 



Uses — Wood hard, heavy, strong, coarse-grained, tough, difficult to split, light 

 brown with wide, paler sapwood. Considered superior to that of the 

 other American elms. Used for planks, bridge construction, cheese boxes, 

 wheel hubs, agricultural implements, and railroad ties. 



