13. EYSENHARDTIA H. B. K.
Small glandular-punctate trees or shrubs, with slender terete branchlets. Leaves alternate, equally pinnate, petiolate; leaflets oblong, mucronate or emarginate at apex, short-petiolulate, numerous, stipellate; stipules subulate, caducous. Flowers short-pedicellate, in long spicate racemes, terminal or axillary, with subulate caducous bracts; calyx-tube campanulate, conspicuously glandular-punctate, 5-toothed, the acute teeth nearly equal, persistent; disk cupuliform, adnate to the base of the calyx-tube; corolla subpapilionaceous; petals erect, free, nearly equal, oblong-spatulate, rounded at apex, unguiculate, creamy white; standard concave, slightly broader than the wing and keel-petals; stamens 10, inserted with the petals, the superior stamen free, shorter than the others united to above the middle into a tube; anthers uniform, oblong; ovary subsessile, contracted into a long slender uncinate style geniculate and conspicuously glandular below the apex; stigma introrse, oblique; ovules 2 or 3, rarely 4, attached to the inner angle of the ovary, superposed. Legume small, oblong or linear-falcate, compressed, tipped with the remnants of the style, indehiscent, pendent. Seeds usually solitary, rarely 2, oblong-reniform, without albumen; seed-coat coriaceous; embryo filling the cavity of the seed; cotyledons flat, fleshy; radicle superior, short and erect.
Eysenhardtia is confined to the warmer parts of the New World, and is distributed from western Texas and southern New Mexico and Arizona to southern Mexico, Lower California, and Guatemala. Four species are distinguished; of these three species occur within the territory of the United States, and in northern Mexico, and one species is found only in Guatemala. Lignum nephriticum formerly celebrated in Europe for its reputed medical properties and for the fluorescence of its infusion in spring water is the wood of the shrubby Eysenhardtia polystachya Sarg. of western Texas and Mexico.
Of the North American species one is a small tree.
The generic name is in honor of Karl Wilhelm Eysenhardt (1794—1825), Professor of Botany in the University of Königsberg.
1. [Eysenhardtia orthocarpa] S. Wats.
Leaves 4′—5′ long, with a pubescent rachis grooved on the upper side, 10—23 pairs of leaflets, and small scarious deciduous stipules; leaflets oval, rounded or slightly emarginate at apex, with a stout petiolule and minute scarious deciduous stipels, pale gray-green, glabrous or slightly puberulous on the upper surface, conspicuously glandular, with chestnut-brown glands, and pubescent especially on the prominent midrib on the lower surface, reticulate-veined, ½′—⅔′ long, ⅛′—¼′ wide, with thickened slightly revolute margins. Flowers opening in May, nearly ½′ long, on slender pubescent pedicels, in axillary pubescent spikes 3′—4′ long; calyx many-ribbed, pubescent, conspicuously glandular, half as long as the white petals ciliate on the margins, and of nearly equal size and shape. Fruit ½′ long, pendent, nearly straight or slightly falcate, thickened on the edges, with usually a single seed near the apex; seed compressed, light reddish brown, ¼′ long.
A tree, occasionally 18°—20° high, with a trunk 6′—8′ in diameter, separating 3° or 4° above the ground into a number of slender branches, and branchlets coated when they first appear with ashy gray pubescence disappearing during the second year, and then reddish brown and roughened by numerous glandular excrescences; or more often a low rigid shrub. Bark of the trunk about 1/16′ thick, light gray, and broken into large plate-like scales, exfoliating on the surface into thin layers. Wood heavy, hard, close-grained, light reddish brown, with thin clear yellow sapwood of 7 or 8 layers of annual growth.
Distribution. Dry gravelly soil, on arid slopes and dry ridges; valley of the upper Guadalupe River, western Texas, to the Santa Catalina and Santa Rita Mountains, southern Arizona, and southward into northern Mexico; arborescent in the United States only near the summit of the Santa Catalina Mountains.