﻿Trees of New York State 179 



FAGACEAE 



Quercus macrocarpa Michx. 



Bur Oak, Mossy-cup Oak, Over-cup Oak 



Habit — Oue of the largest of American oaks, under optimum eonditiona 

 sometimes 170 feet in height Avith a trunk 4-7 feet in diameter which is 

 free of branches for 50 feet or more. Usually smaller, becoming shrubby 

 at the northern limits of its range. CrowTi in the open broad and round- 

 topped, AA-ith massive, spreading limbs and drooping, bushy branchlets. 



Leaves — ^ Alternate, obovate or oblong, G-12 inches long, 3-6 inches wide, 

 cuneate at the base, sinuately cut or nearly divided into 5-7 lobes, the 

 terminal lobe the larger and crenately lobed. At maturity leaves thick, 

 firm, lustrous and usually smooth above, greenish or silvery pubescent 

 below. Petioles stout, %-l inch long. 



Flowers — ■ In our range appearing in late May or early June Avhen the 

 leaves are about one-fourth grown, monoecious. Staminate flowers in 

 interrupted, hairy, filiform, pendulous, deciduous anients, 4-6 inches long 

 which are borne on the grow^th of the preceding season or from the axils 

 of the inner scales of the terminal bud. Calj^ hemi-spherieal, yellowish 

 green, pubescent vath 4-6 laciniate lobes. Stamens ^Q, with short fila- 

 ments and yellow, glabrous anthers. Pistillate flowei's sessile or pedun- 

 culate, solitary or paired, borne in the axils of the leaves of the season, 

 each subtended by broadly ovate, pubescent involucral scales. Calyx 

 eampanulate, shallowly lobed, adnate to the ovary. Pistil enclosed aside 

 from the 3 spreading styles Avhicli are reddish and stigma tie on their 

 inner surface. 



Fnxit — A sessile or short-pedunculate acorn ripening the first season. Nut 

 chestnut-broAni, oval or broadly ovate, rounded and finely pubescent at 

 the apex, from +,,-,-2 inches long, enclosed from one-half to its whole 

 length in the cup. Cup bowl-shaped, pale brown and pubescent within, 

 hoary-tomentose without, with pointed, imbricated scales, the upper pro- 

 longed to form a fringe. 



Winter characters — Twigs stout, pale-lenticellate, glabrous, j)ale orange- 

 yellow, at length dark browni. Older twigs often develop corky wings. 

 Buds alternate, those near the branch-tip clustered about the terminal 

 bud, broadly ovate, obtuse, pubescent, pale reddish brown, Vs-Vi of an 

 iiu-h long. Mature bark pale bvowu. medium thick, divided by deep fur- 

 rows into irregular, scaly plates. 



Habitat — A bottom-land species preferring rich, deep, moist soils, more 

 rarely on drier, upland sites. 



Range — Nova Scotia to Manitoba and IMontana. south to Pennsylvania. Ten- 

 nessee and Texas. Zones A, B, and ('. 



Uses — A valua1)le timber species jiroducing lumber equivalent in ((iiality to 

 that of Wliite Oak. AVood hard, heavy, strong, durable, rich brown with 

 paler sapwood. Prized for fuiiiiture, cooperage, interior finish, railroad 

 ties, etc. 



