238 TREES OF NORTH AMERICA 



petioles in falling leaving slightly elevated semiorbicular more or less obcordate leaf-scars 

 broader than high, marked by the ends of numerous scattered fibro-vascular bundles; 

 stipules obovate to lanceolate, scarious, caducous, or those of upper leaves occasionally 

 persistent through the season. Flowers vernal with or after the unfolding of the leaves: 

 staminate solitary in the axils of lanceolate acute caducous bracts, or without bracts, in 

 graceful pendulous clustered aments, from separate or leaf -buds in the axils of leaves of the 

 previous year, or from the axils of the inner scales of the terminal bud or from those of the 

 leaves of the year; calyx carnpanulate, lobed or divided to the base into 4-7, usually 6, 

 membranaceous lobes; stamens 4-6, rarely 2, or 10-12, inserted on the slightly thickened 

 torus, with free filiform exserted filaments and ovate-oblong or subglobose glabrous or rarely 

 hairy 2-celled usually yellow anthers; pistillate solitary, subtended by a caducous bract 

 and 2 bractlets, in short or elongated few-flowered spikes from the axils of leaves of the year; 

 calyx urn-shaped, with a short campanulate 6-lobed limb, the tube adnate to the incom- 

 pletely 3 or rarely 4 or 5-celled ovary inclosed more or less completely by an accrescent in- 

 volucre of imbricated scales, becoming the cup of the fruit; styles as many as the cells of 

 the ovary, short or elongated, erect or incurved, dilated above, stigmatic on the inner face or 

 at apex only, generally persistent on the fruit; ovules anatropous or semianatropous, 2 in each 

 cell. Fruit a nut (acorn) maturing in one or in two years, ovoid, subglobose, or turbinate, 

 short-pointed at apex, 1-seeded by abortion, marked at base by a large conspicuous cir- 

 cular scar, with a thick shell, glabrous or coated on the inner surface with pale tomentum, 

 more or less surrounded or inclosed in the accrescent cupular involucre of the flower (cup), 

 its scales thin or thickened, loosely or closely imbricated. Seed marked at base or at 

 apex or rarely on the side by the abortive ovules; cotyledons thick and fleshy, usually 

 plano-convex and entire. 



Quercus inhabits the temperate regions of the northern hemisphere and high altitudes 

 within the tropics, ranging in the New World southward to the mountains of Colombia 

 and in the Old World to the Indian Archipelago. Two hundred and seventy-five species 

 have been described; of the North American species fifty-four are large or small trees. 

 Of exotic species, the European Quercus Robur L., and Quercus sessiliflora Salisb., have been 

 frequently cultivated as ornamental trees in the eastern United States, where, however, 

 they are usually short-lived and unsatisfactory. Many of the species are important 

 timber-trees; their bark is often rich in tannin and is used for tanning leather, and all pro- 

 duce wood valuable for fuel and in the manufacture of charcoal. 



Quercus is the classical name of the Oak-tree. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 



Fruit maturing at the end of the second season (except 22); shell of the nut silky to- 



mentose on the inner surface; leaves or their lobes bristle-tipped. BLACK OAKS. 

 Stamens usually 4-6; styles elongated, finally recurved; abortive ovules apical. 

 Leaves deciduous in their first autumn or winter. 

 Leaves pinnately lobed, convolute in the bud. 

 Leaves green on both surfaces. 



Scales of the cup of the fruit closely appressed. 



Leaves usually dull on the upper surface, 7-11-lobed; cup of the fruit cup- 

 shaped or in one variety broad and saucer-shaped, its scales thin. 



1. Q. borealis (A). 

 Leaves lustrous. 



Leaves dimorphous, 5-7-lobed, axillary clusters of hairs large and promi- 

 nent; cup of the fruit saucer-shaped or in one form deep cup-shaped. 



2. Q. Shumardii (A, C). 

 Leaves similar on upper and lower branches. 

 Cup of the fruit turbinate or deep cup-shaped. 



Leaves 5-lobed, the lobes usually entire, rarely furnished with tufts of 

 axillary hairs below. 3. Q. texana (C). 



