Quercus turbinella |
Quercus ajoensis |
|
---|---|---|
grey oak, shrub live oak, Sonoran scrub oak, turbinella oak |
Ajo Mountain scrub oak |
|
Habit | Shrubs or small trees, evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly. | Shrubs, rarely trees, evergreen, to 2-3 m. Bark gray, scaly or furrowed. |
Twigs | brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate. |
light brown, 1-2 mm diam., inconspicuously short stellate-pubescent or glabrate. |
Buds | brown, round to ovoid, 1-2 mm, minutely pubescent. |
brown or reddish brown, ovoid or globose, 1-1.5 mm, variously short stellate-pubescent, tomentose, or glabrate. |
Leaves | 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. |
petiole (2-)3-4 m. Leaf blade ovate to narrowly ovate or oblong, (10-)15-35(-50) × (5-)10-20(-30) mm, rather leathery, base cordate, rarely rounded, margins crispate, sometimes flat, cartilaginous, with 4-6(-8) long-attenuate, spinose-awned teeth on each side, secondary veins 5-8 on each side, whitish, apex acute or obtuse with bristly distal teeth; surfaces abaxially blue-green, waxy-glaucous, microscopically papillose, glabrous, sometimes sparsely stellate-pubescent along midrib, adaxially blue-green, glaucous, glabrous or sparingly stellate-pubescent along midrib, secondary veins raised on both surfaces. |
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. |
solitary or paired on thin axillary peduncle (5-)30-50 mm; cup shallowly cup-shaped, thin, 3-4 mm deep × 6-8(-10) mm wide, enclosing only base of nut, scales brownish, moderately tuberculate, pubescent; nut oblong to narrowly ovoid, 12-15 × 5-8 mm. |
Cotyledons | distinct. |
distinct. |
Quercus turbinella |
Quercus ajoensis |
|
Phenology | Flowering spring. | Flowering in spring. |
Habitat | Dry desert slopes, often in juniper and pinyon woodlands | Rare to locally abundant on igneous slopes |
Elevation | 800-2000 m (2600-6600 ft) | 500-1500 m (1600-4900 ft) |
Distribution |
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Sonora, and probably n Chihuahua)
|
AZ; Mexico (Baja California) |
Discussion | 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Populations of Quercus ajoensis in southern New Mexico show characteristics suggesting introgression from hybridization with Quercus toumeyi, such as increased twig and leaf pubescence and sometimes the prominent golden puberulum of the abaxial leaf surfaces. Hybrids between Q. ajoensis and both Q. turbinella and Q. gambelii (Utah) are also known. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Quercus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. dumosa var. turbinella, Q. subturbinella | Q. turbinella subsp. ajoensis, Q. turbinella var. ajoensis |
Name authority | Greene: Ill. W. Amer. Oaks 1: 37. (1889) | C. H. Muller: Madroño 12: 140. (1954) |
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