Queracus valuti'na (coccin'ea var. tincto'ria), Black (Scarlet) Oak (Quercitron). -- The (inner) bark, U.S.P. 1820-1870. Trees 24-30 M. (80-100 degrees) high, 1-1.2 M. 3-4 degrees) thick, leaves oblong, lobed, 15-20 Cm. (6-8') long, mucronate; fruit, acorns, 12-18 Mm. (1/2-3/4') long, 12 Mm. (1/2') thick, cupule thick, shallow; bark resembles the preceding, only reddish-brown, gives saliva brownish-yellow color; contains tannin 6-12 p.c., quercitrin (red-bown coloring matter, dyeing yellow wool, silks, etc.), CHO, with diluted acids yields isodulcite, CHO, and yellow quercetin, CHO. In the South barks of Q. nigra and Q. digitata (falcata), used for this, although these have a much coarser texture and a deep reddish-brown color.
Queracus Ro'bur, Common European or English Oak. -- Tall tree, 24-30 M. (80-100 degrees) high, having 3 forms: (a) Q. pubes'cens (old leaves hairy); (b) Q. peduncula'ta (leaves smooth, pistillate flowers, and fruit on peduncles; (c) A. sessiliflo'ra (leaves smooth, flowers and fruit sessile, petioles long). These have many varieties, all resembling Q. alba.
Quercus digita'ta (falca'ta, L. falcatus -- i.e., leaf-lobes scythe-shaped), Spanish or Red Spanish Oak. -- Maryland-Florida. Tree 18-21 M. (60-70 degrees) high, leaves grayish, 3-5-lobed, finger- or scythe-shaped. Bark rich in tannin, wood reddish, coarse-grained; used in tanning, sometimes called quercitron.
Quercus marylan'dica (ni'gra, ferrugin'ea), Black, Barren, or Iron Oak (Black Jack). Southern States. Tree 9-12 M. (30-40 degrees) high, leaves cuneate, 3-5-lobed, rusty, pubescent beneath, shining above. Of little value.
Quercus virginia'na (virens, L. vireo, green, fresh, flourishing), Live Oak. -- Maryland-Florida. Tree 12-18 M. (40-60 degrees) high. Bark rich in tannin, wood fine-grained; used in shipbuilding.
Queracus su'ber, Cork Oak, Alcornoque (Savanna Bark). -- Mediterranean Basin, S. United States. Small tree, 9-15 M. (30-50 degrees) high, leaves toothed, ovate; bark with an elastic suberous layer 2.5-5 Cm. (1-2') thick, collected every 8-10 years, and constitutes our cork of commerce. When finely powdered, sold as suberin for absorbent purposes, which name is applied to one of its constituents (fat). There are about 80 species of Quercus, ranging from shrubs to trees; one-half of these grow in the United States, and may, with their acorns, be used similarly. Acorns sometimes are roasted--semen quercus tostum, and used as a substitute for coffee; contain fixed oil, starch, citric acid, uncrystallized and quercite sugars.