2. [Bursera microphylla] A. Gray.
Leaves glabrous, deciduous, 1′—1¼′ long, with a slender narrowly winged rachis and petiole and usually 10—20 oblong or oblong-obovate leaflets rounded at apex, obliquely cuneate at base, sessile, about ¼′ long and 1/12′ wide. Flowers appearing in June before the leaves, ⅙′ long on slender pedicels from the axils of minute acuminate caducous bracts, in mostly 3-flowered clusters ¼′ in length; staminate, calyx-lobes ovate, acute; petals 5, lanceolate, acuminate, revolute on the margins, 3 or 4 times longer than the calyx-lobes, white; stamens shorter than the petals; pistillate flower not seen. Fruit ripening in October, ellipsoid or slightly obovoid, solitary, drooping on the thickened pedicel ⅕′ in length, 3-angled, ¼′ long, red, glabrous, splitting into three valves; nutlets usually ovoid, acute, narrow at base, thin walled, 3-angled, gray with a deep depression at base.
A tree, rarely 10°—12° high, with a short trunk 2½′—3′ in diameter, stout erect and spreading branches, forming a wide round-topped head, and slender glabrous red branchlets, roughened during their first year by the crowded scars of fallen leaves; more often a low shrub. Bark of the trunk pale yellow, separating into membranaceous scales, the outer layer thin and firm, the inner layer corky, reddish brown, ½′ thick. Wood hard, close-grained, pale yellow.
Distribution. Colorado Desert, between Fish Creek and Carriso Creek about twenty-five miles from the Mexican Boundary, on “banks of dry washes, in hard sterile soil covered with boulders” (E. H. Davis), Imperial County, California; near Maricopa, Pinal County, Arizona, and in Lower California and Sonora; reported as a tree only from California.
XXIX. MELIACEÆ.
Trees or shrubs, with hard wood and alternate pinnate leaves, without stipules. Flowers in panicles, perfect, regular; calyx 5-lobed, the lobes contorted (in Swietenia) in the bud, persistent; petals 5, convolute in the bud; stamens inserted at the base of the disk; filaments united into a tube; anthers introrse, 2-celled, the cells opening longitudinally; ovary 3—5-celled, free, surrounded at base by an annular or cup-shaped disk; styles united, dilated into a 5-lobed stigma; ovules numerous in each cell, suspended, semianatropous; raphe ventral; micropyle superior. Fruit a capsule (in Swietenia) or drupe. Seeds often winged; embryo with leafy cotyledons.
A family with about forty genera chiefly confined to the tropics, with a single representative, Swietenia, in southern Florida. Melia Azedarach L., of this family, the China-tree or Pride of India, with drupaceous fruits, has long been cultivated in the southern states, where it now often grows spontaneously.
1. SWIETENIA Jacq.
Trees, with heavy dark red wood. Leaves abruptly pinnate, glabrous, long-petiolate, persistent; leaflets opposite, petiolulate, usually oblique at base. Flowers small, in axillary or subterminal panicles produced near the end of the branches; calyx minute; petals spreading; staminal tube urn-shaped, connate with the petals, 10-lobed, the lobes convolute in the bud; anthers 10, fixed by the back below the sinuses of the staminal tube, included; ovary ovoid, 5-celled, the cells opposite the petals; style erect, longer than the tube of the stamens; stigma discoid, 5-rayed. Fruit a 5-celled 5-valved capsule septicidally dehiscent from the base, the valves separating from a persistent 5-angled axis thickened toward the apex and 5-winged toward the base. Seeds suspended from near the summit of the axis, imbricated in 2 ranks, compressed, emarginate, produced above into a long membranaceous wing with the hilum at its apex and transversed by the raphe; embryo transverse; cotyledons conferruminate with each other and with the thin fleshy albumen; radicle short, papillæform.