Page:EB1911 - Volume 19.djvu/972

 the English oak, and covered with a whitish bark that gives a marked character to the tree. The leaves are large, often irregular in form, usually with a few deep lobes dilated at the end; they are of a bright light green on the upper surface, but whitish beneath; they turn to a violet tint in autumn. The egg-shaped acorns are placed singly or two together on short stalks; they are in most years sparingly produced, but are occasionally borne in some abundance. On rich loams and the alluvial soils of river-valleys, when well drained, the tree attains a large size, often rivalling the giant oaks of Europe; trunks of 3 or 4 ft. in diameter are frequently found, and sometimes these dimensions are greatly exceeded. The wood is variable in quality and, though hard in texture, is less durable than the best oak of British growth; the heart-wood is of a light reddish brown varying to an olive tint; a Canadian specimen weighs the cubic foot.

Q. obtusiloba, the post oak of the backwoodsman, a smaller tree with rough leaves and notched upper lobes, produces an abundance of acorns and good timber, said to be more durable than that of the white oak.

The pin oak, sometimes called the “burr-oak,” Q. macrocarpa, is remarkable for its large acorns, the cups bordered on the edge by a fringe of long narrow scales; the leaves are very large, sometimes from 10 in. to 1 ft. in length, with very deep lobes at the lower part, but dilated widely at the apex, and there notched. The tree is described by Prof. C. S. Sargent (Silva of North America) as one of the most valuable timber trees of North America, its wood being, superior in strength even to that of Q. alba, with which it is commercially confounded. The over-cup oak, Q. lyrata, is a large tree, chiefly found on swampy land in the southern states; the lyrate leaves are dilated at the end; the globose acorns are nearly covered by the tuberculated cups. In the woods of Oregon, from the Columbia river southwards, an oak is found bearing some resemblance to the British oak in foliage and in its thick trunk and widely-spreading boughs, but the bark is white as in Q. alba; it is Q. Garryana, the western oak of T. Nuttall. This tree acquires large dimensions, the trunk being often from 4 to 6 ft. in diameter; the wood is strong, hard and close-grained; the acorns are produced in great quantity, and are used by the Indians as food.

The red oak, Q. rubra, has thin large leaves on long petioles, the lobes very long and acute, the points almost bristly; they are pink when they first expand in spring, but become of a bright glossy green when full-grown; in autumn they change to the deep purple-red which gives the tree its name. Common throughout the northern and middle states and Canada, the red oak attains a large size only on good soils; the wood is of little value, being coarse and porous, but it is largely used for cask-staves; the bark is a valuable tanning material.

A species nearly allied is the scarlet oak, Q. coccinea, often confounded with the red oak, but with larger leaves, with long lobes ending in several acute points; they change to a brilliant scarlet with the first October frosts, giving one of the most striking of the various glowing tints that render the American forests so beautiful in autumn. The trunk, though often of considerable size, yields but an indifferent wood, employed for similar purposes to that of Q. rubra; the bark is one of the best tanning materials of the country. Both these oaks grow well in British plantations, where their bright autumn foliage, though seldom so decided in tint as in their native woods, gives them a certain picturesque value.

Nearly akin to these are several other forms of little but botanical interest; not far removed is the black or dyer’s oak, Q. tinctoria, a large and handsome species, with a trunk sometimes 4 ft. in diameter, not uncommon in most forests east of the Mississippi, especially in somewhat upland districts. The leaves are frequently irregular in outline, the lobes rather short and blunt, widening towards the end, but with setaceous points; the acorns are nearly globular. The wood is coarsely grained, as in all the red-oak group, but harder and more durable than that of Q. rubra, and is often employed for building and for flour-barrels and cask-staves. The bark, very dark externally, is an excellent tanning substance; the inner layers form the quercitron of commerce, used by dyers for communicating to fabrics various tints of yellow, and, with iron salts, yielding a series of brown and drab hues; the colouring property depends on a crystalline principle called quercitrin, of which it should contain about 8%. The cut-leaved oaks are represented in eastern Asia by several species, of which Q. mongolica is widely spread over Dahuria, north China and the adjacent countries; one of the Chinese silkworms is said to feed on the leaves.

The chestnut oaks of America represent a section distinguished by the merely serrated leaves, with parallel veins running to the end of the serratures. Q. Prinus, a beautiful tree of large growth, and its subspecies castanea and montana, yield good timber. Q. Chinquapin or prinoides, a dwarf species, often only 1 ft. in height, forms dense miniature thickets on the barren uplands of Kansas and Missouri, and affords abundant sweet acorns; the tree is called by the hunters of the plains the “shin-oak.” Q. castaneaefolia, represented in fig. 6,