8. GLEDITSIA L.
Trees, with furrowed bark, slender terete slightly zigzag branchlets thickened at the apex and prolonged by axillary buds, thick fibrous roots, the trunk and branches often armed with stout simple or branched spines or abortive branchlets developed from supra-axillary or adventitious buds imbedded in the bark. Winter-buds minute, 3 or 4 together, superposed, the 2 or 3 lower without scales and covered by the scar left by the falling of the petiole, the upper larger, nearly surrounded by the base of the petiole and covered by small scurfy scales. Leaves long-petiolate, often fascicled in earlier axils, abruptly pinnate or bipinnate, the pinnæ increasing in length from the base to the apex of the leaf, the lowest sometimes reduced to single leaflets; deciduous; leaflets thin, their margins irregularly crenate, without stipels; stipules minute, caducous. Flowers regular, polygamous, minute, green or white on short pedicels, in axillary or lateral simple or fascicled racemes, with minute scale-like caducous bracts; calyx campanulate, lined with the disk, 3—5-lobed, the narrow lobes nearly equal; petals as many as the lobes of the calyx, nearly equal; stamens 6—10, inserted with the petals on the margin of the disk, exserted; filaments free, filiform, erect; anthers uniform, much smaller and abortive in the pistillate flower; ovary subsessile, rarely bicarpellary, rudimentary or 0 in the staminate flower; styles short; stigma terminal, more or less dilated, often oblique; ovules 2 or many, suspended from the angle opposite the posterior petal. Legume compressed, many-seeded, elongated, straight and indehiscent, or 1—3-seeded, ovoid and tardily dehiscent. Seeds transverse, ovoid to suborbicular, flattened, attached by a long slender funicle; seed-coat thin, crustaceous, light brown; embryo surrounded by a layer of horny orange-colored albumen; cotyledons subfoliaceous, compressed; radicle short, erect, slightly exserted.
Gleditsia is confined to eastern North America, where three species occur, southwestern Asia, China, Formosa, Japan, and west tropical Africa. It produces strong, durable, coarse-grained wood. In Japan the pods are used as a substitute for soap.
The generic name is in honor of Johann Gottlieb Gleditsch (1714—1786), professor of botany at Berlin.
CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES.
Legume linear-oblong, elongated, many-seeded, indehiscent. Legume 12′—18′ long, with pulp between the seeds; ovary hoary-tomentose.1. [G. triacanthos] (A, C). Legume 4′—5′ long, without pulp between the seeds.2. [G. texana] (C). Legume oval, oblique, 1—3-seeded, without pulp, tardily dehiscent; ovary glabrous.3. [G. aquatica] (A, C).
1. [Gleditsia triacanthos] L. Honey Locust.
Leaves 7′—8′ long, 18—28-foliolulate or sometimes bipinnate, with 4—7 pairs of pinnæ, those of the upper pair 4′—5′ long, when they unfold hoary-tomentose, and at maturity pubescent on the petiole and rachis, the short stout petiolules, and the under surface of the midrib of the oblong-lanceolate leaflets, unequal at base, acute or slightly rounded at apex, remotely crenulate-serrate, dark green and lustrous above, dull yellow-green below, 1′—1½′ long and ½′ wide; turning in the autumn pale clear yellow. Flowers appearing in June when the leaves are nearly fully grown from the axils of leaves of previous years; the staminate in short many-flowered pubescent racemes 2′—2½′ long and often clustered; the pistillate in slender graceful few-flowered usually solitary racemes 2½′—3½′ long; calyx campanulate, narrowed at base, the acute lobes thickened, revolute and ciliate on the margins, villose with pale hairs, rather shorter than and half as wide as the erect acute petals; filaments pilose toward the base; anthers green; pistil rarely of 2 carpels, hoary-tomentose. Fruit 12′—18′ long, dark brown, pilose and slightly falcate, with straight thickened margins, 2 or 3 together in short racemes on stalks 1′—1½′ long, their walls thin and tough, contracting in drying by a number of corkscrew twists, and falling late in the autumn or early in winter; seeds oval, ⅓′ long, separated by thick succulent pulp.
A tree, 75°—140° high, with a trunk 2°—3° or occasionally 5°—6° in diameter, slender spreading somewhat pendulous branches forming a broad open rather flat-topped head, and branchlets marked by minute lenticels, at first light reddish brown and slightly puberulous, soon becoming lustrous and red tinged with green, and in their second year greenish brown and armed with stout rigid long-pointed simple or 3-forked spines at first red, and bright chestnut-brown when fully grown, or rarely unarmed (var. inermis Pursh.). Bark of the trunk ½′—¾′ thick, divided by deep fissures into long narrow longitudinal ridges and roughened on the surface by small persistent scales. Wood hard, strong, coarse-grained, very durable in contact with the ground, red or bright red-brown, with thin pale sapwood of 10—12 layers of annual growth; largely used for fence-posts and rails, for the hubs of wheels, and in construction.