Leaves narrowly lanceolate, acuminate or rarely rounded at apex, abruptly cuneate or slightly rounded at base, and remotely serrate with minute glandular teeth, when they unfold puberulous above and densely tomentose below, and at maturity coriaceous, bright yellow-green and glabrous on the upper and tomentose on the lower surface, 1½′—3′ long, ¼′—½′ wide, with a thick conspicuous midrib grooved on the upper side, and numerous thin primary veins connected by reticulate veinlets; deciduous in spring or early summer; petioles thick, ⅓′—½′ in length. Flowers appearing in June, ¼′ in diameter, in hoary-tomentose panicles 2′—3′ across; petals oblong; inner surface of the disk pilose. Fruit fully grown by the end of August, ¼′ long, persistent on the branches after opening until the spring of the following year; conspicuous from the contrast of the bright red faded petals and the white silky pubescence of the calyx and carpels; seed 1/12′ long, and one third as long as its wing.
A tree, 18°—20° high, with a slender often hollow trunk 5′—6′ in diameter, rigid upright contorted branches, and slender branchlets at first bright reddish brown and more or less thickly covered with hoary tomentum, becoming light brown or gray in their second year and marked by large elevated leaf-scars; or more often a low shrub. Winter-buds: axillary minute, acuminate, reddish brown, pubescent. Bark about 1/16′ thick, dark red-brown, and broken on the surface into small square persistent plate-like scales. Wood very heavy, hard, close-grained, dark rich brown streaked with red, with 14 or 15 layers of annual growth.
Distribution. Bottoms and rocky sides of gulches, or on grassy slopes; mountain ranges of extreme southwestern New Mexico (Guadalupe Cañon, teste E. A. Means), southern Arizona, Sonora, and Lower California; arborescent and of its largest size in Arizona on the Santa Catalina Mountains at altitudes of about 5000° above the sea.
2. LYONOTHAMNUS A. Gray.
A tree or shrub, with scaly bark exfoliating in long strips, stout terrete pubescent ultimately glabrous branchlets, and scaly, acuminate buds. Leaves opposite, long-petiolate, lanceolate, acuminate, rounded or cuneate at base, entire, finely crenulate-serrate or serrulate lobulate below the middle, or sometimes irregularly pinnately parted into 3—8 linear-lanceolate remote lobulate segments, coriaceous, transversely many-veined, dark green above, paler and more or less pubescent below, persistent; stipules lanceolate, acute, minute, caducous. Flowers on slender pedicels, in broad compound terminal pubescent cymose corymbs, with minute acute persistent bracts and bractlets; calyx-tube hemispheric, with 1—3 bractlets, tomentose on the outer surface, the lobes nearly triangular, slightly keeled, apiculate, persistent; disk 10-lobed, with a slightly thickened margin; petals 5, orbicular, sessile, white; stamens 15, inserted in pairs opposite the petals and singly opposite the sepals; filaments subulate, incurved, as long as the petals; anthers oblong, 2-celled, the cells opening longitudinally; carpels 2, inserted in the bottom of the calyx-tube, forming a superior glandular, hairy ovary; styles 2, spreading; stigmas capitate, truncate; ovules 4 in each cell, suspended; micropyle superior; raphe ventral. Fruit of 2 woody ovoid glandular-setulose carpels, dehiscent on the ventral and partly dehiscent on the dorsal suture. Seeds ovate-oblong, pointed at the ends; seed-coat light brown, thin and membranaceous; hilum orbicular, apical; raphe broad and wing-like; cotyledons oblong, acuminate, twice as long as the straight radicle directed toward the hilum.
Lyonothamnus is represented by a single species found only on the islands off the coast of southern California.
Lyonothamnus, in honor of its discoverer, William S. Lyon.
1. [Lyonothamnus floribundus] A. Gray. Ironwood.
