Sonoran scrub oak, more...
[Quercus dumosa var. turbinella (Greene) Jepson]
Shrubs or small trees , evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly. Twigs brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate. Buds brown, round to ovoid, 1-2 mm, minutely pubescent. Leaves: petiole 1-4 mm. Leaf blade elliptic or ovate, (1.5-)20-30 × (5-)10-15(-20) mm, thick, leathery, base cordate or rounded, margins planar or slightly crisped-undulate, coarsely 3-5-toothed or very shallowly lobed on each side, teeth spinose with spines 1-1.5 mm, secondary veins 4-8 on each side, apex acute or obtuse; surfaces abaxially yellow or reddish, usually glaucous, minutely stellate-puberulent, adaxially grayish, glaucous, or yellowish glandular, glabrous or sparsely and minutely stellate-pubescent. Acorns solitary or several, on axillary peduncle 10-40 mm; cup hemispheric or shallowly cup-shaped, 4-6 mm deep × 8-12 mm wide, covering 1/4-1/2 nut, scales tightly appressed, ovate, moderately tuberculate, grayish or yellowish puberulent; nut light brown, ovoid, to 20 × 11 mm, minutely puberulent or glabrate. Cotyledons distinct. Flowering spring. Dry desert slopes, often in juniper and pinyon woodlands; 800-2000 m; Ariz., Calif., Colo., N.Mex., Nev., Tex., Utah; Mexico (Baja California, Sonora, and probably n Chihuahua). Formerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Q . turbinella . Quercus john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q . turbinella . The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q . john-tuckeri shares at least as many characteristics with Q . berberidifolia as with Q . turbinella . Thus, treatment of these two taxa as varieties of the same species is inappropriate. Quercus turbinella forms putative hybrid swarms with Q . gambelii (see treatment), as well as with Q . grisea .
Plant: shrub or small tree; 1-3(-6) m high, the bark light gray, rough, fissured; young twigs densely woolly (rarely glabrous) when young, smooth reddish-brown beneath hairs, the older twigs glabrescent, gray, sometimes blackened, remaining more or less smooth Leaves: unlobed, oblong-elliptic, ovate to suborbicular, 1.3-5.5(-6.5) cm long, 0.8-3(-4.5) cm wide, 1.3-2 times as long as wide, densely to sparsely covered with stellate and glandular hairs to glabrous below, moderately to sparsely covered with hairs to glabrous above, glabrescent with age, persisting 1-2 years; stellate hairs of lower leaf surface sometimes nearly scale-like, flattish, most with 7-13 arms; apex acute with sharp mucronate tip; base truncate to rounded; petiole 1-5 mm long, yellowish or reddish, moderately to densely covered with hairs; midvein nearly flat above, prominent below; lateral veins about 4-9 pairs, usually faint above, moderately prominent below; secondary veins forming a reticulate pattern above and below; blade usually bluish-green, coriaceous, more or less flat, dull or slightly lustrous above; margin with 1-8 sharply pointed, spinose teeth per side (rarely entire) INFLORESCENCE: staminate flowers in aments; pistillate flowers solitary or in groups on spikes, these sometimes abbreviated, each pistillate flower with a separate involucre Flowers: mostly wind-pollinated, unisexual, the perianth much reduced or absent; staminate flowers in heads or aments, the perianth greenish, the stamens 4-7; pistillate flowers usually tricarpellate, solitary or in clusters of about 3 or more, subtended individually or in groups by an involucre that develops into a woody cupule enclosing or subtending the mature fruit(s) Fruit: ACORNS 1.2-2.5 cm long, the peduncle 0-4 cm long; cap hemispheric, 5-8 mm long, 10-13 mm across, short woolly within; scales with thickened bases; nut-shell sparsely pilose within Misc: In chaparral, pinyon-juniper, and transitions between these and grasslands or desert; 600-2300 m (2000-7600 ft); Mar-Jun (fr. Jul-Sep) REFERENCES: Landrum, Leslie R. Fagaceae. 1994. J. Ariz. – Nev. Acad. Sci. Volume 27, 203-214