HICKORY, a shortened form of the American Indian name pohickery. Hickory trees are natives of eastern North America, and belong to the genus Carya (or Hicoria of many Ameri can botanists) of the family Juglandaceae. They are closely allied to the walnuts (Juglans), the chief or at least one very obvious difference being that, whilst in the hickory the husk which covers the shell of the nut separates into four valves, in the walnut it consists of but one piece, which bursts irregu larly. The timber is both strong and heavy, and remarkable for its extreme elasticity. It is very extensively employed in manu facturing axle-trees, chair-backs, axe-handles, whip-handles and other articles requiring great strength and elasticity. The spe cies which furnish the best wood are Carya ovata (shellbark hickory), C. alba (mocker-nut), C. Pecan (pecan or pacane nut), and C. glabra (pig-nut), that of the last named, on account of its extreme tenacity, being preferred for axle-trees and axe-handles. The wood of C. ovata splits very easily and is very elastic, so that it is much used for making whip-handles and baskets.
Most of the hickories form fine trees of from 6o to 90 ft. in height, with straight, symmetrical trunks, well-balanced ample heads, and bold, handsome, pinnated foliage. When confined in the forest they shoot up so to 6o ft. without branches, but when standing alone they expand into a fine head, and produce a lofty round-headed pyramid of foliage. They have all the qualities necessary to constitute fine grace ful park trees. The most orna mental of the species are pecan, the mocker-nut or big-bud hick ory, and the pig-nut, all produc ing delicious nuts.
The husk of the hickory nut, as already stated, breaks up into four equal valves or sep arates into four equal por tions in the upper part, while the nut itself is tolerably even on the surface, but has four or more blunt angles in its transverse outline. The wild hickory nuts of the American markets are chiefly the produce of C. ovate, called the shell-bark or shag-bark hickory because of the roughness of its bark, which becomes loosened from the trunk in long scales. The pecan-nuts, which come from the Southern States, are from 1 in. to 1 2 in. long, smooth, cylin drical, pointed at the ends and thin-shelled, with the kernels full, not like those of most of the hickories divided by partitions, and of delicate and agreeable flavour. The thick-shelled fruits of the pig-nut (C. glabra) are generally left on the ground for swine, squirrels, etc., to devour. In C. cordiformis, the bitter-nut hick ory, the kernel is so very bitter that even the squirrels refuse to eat it.
Since 190o pecan culture has become widely established in the Southern States; in 1926 the total commercial crop was estimated by the U.S. Department of Agriculture at 64,o46,000 lb., valued at $9, 7 7 2,000, of which the states of Oklahoma and Texas pro duced about one-half. In 1925 the total cut of hickory lumber, principally shag-bark, pig-nut, mocker-nut and bitter-nut, amounted to 79,293,00o bd.ft. Its value per thousand at the mill was exceeded only by that of the black walnut and the white ash.
The hickory genus has an interesting geological history, some 20 or more ancestral fossil species being known, ranging from early Eocene to late Pliocene times. In the Miocene these were wide spread across the continents of North America and Europe and in parts of Asia. None, however, survived the Ice Age in Europe, only one (C. cathayensis) remains in Asia, and those in North America became restricted chiefly to the eastern half of the United States, none occurring in or west of the Rocky Mountains, and but a single species (C. mexicana) in Mexico, where it is not widely distributed.