Quercus ajoensis |
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Ajo Mountain scrub oak |
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Habit | Shrubs, rarely trees, evergreen, to 2-3 m. Bark gray, scaly or furrowed. |
Twigs | light brown, 1-2 mm diam., inconspicuously short stellate-pubescent or glabrate. |
Buds | brown or reddish brown, ovoid or globose, 1-1.5 mm, variously short stellate-pubescent, tomentose, or glabrate. |
Leaves | 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 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. |
Quercus ajoensis |
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Phenology | Flowering in spring. |
Habitat | Rare to locally abundant on igneous slopes |
Elevation | 500-1500 m (1600-4900 ft) |
Distribution |
AZ; Mexico (Baja California) |
Discussion | 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. |
Parent taxa | |
Sibling taxa | |
Synonyms | Q. turbinella subsp. ajoensis, Q. turbinella var. ajoensis |
Name authority | C. H. Muller: Madroño 12: 140. (1954) |
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