Quercus vacciniifolia |
Quercus ajoensis |
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huckleberry oak |
Ajo Mountain scrub oak |
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Habit | Shrubs, low spreading to often prostrate, to 1.5 m. Twigs branching at 45° angles or less, reddish brown, 1-1.5 mm diam., flexible, glabrous to sparsely pubesent. | 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. |
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Buds | brown or reddish brown, ovoid or globose, 1-1.5 mm, variously short stellate-pubescent, tomentose, or glabrate. |
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Leaves | blade oblong-ovate, 10-35 × 7-15 mm, flat, thin, leathery, base slightly rounded to acute, secondary veins inconspicuous, 6-8 pairs, branching at 45-60° angles, with weakly thickened cell walls, margins entire or indistinctly and irregularly mucronately toothed, apex acute or rarely obtuse; surfaces abaxially whitish green with waxy layer, glabrous or slightly pubescent with stellate hairs, adaxially dull gray-green, glabrous or sparsely pubescent with stellate hairs. |
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 rarely paired; cup shallowly saucer-shaped to slightly turbinate, 3-4 mm deep × 10-15 mm wide, scales appressed, slightly embedded, moderately silvery brown-pubescent; nut ovoid, 8-17 × 5-10 mm, apex acute; nut scar to 3 mm diam. |
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. |
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Terminal | buds conic, 2.5 mm, scales brown with ciliate margins. |
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Quercus vacciniifolia |
Quercus ajoensis |
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Phenology | Flowering in early summer. | Flowering in spring. |
Habitat | Dry ridges, steep slopes, and rocky areas from montane coniferous zone to near treeline | Rare to locally abundant on igneous slopes |
Elevation | 900-2800 m (3000-9200 ft) | 500-1500 m (1600-4900 ft) |
Distribution |
CA; NV; OR
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AZ; Mexico (Baja California) |
Discussion | Typical high-elevation populations in the Sierra Nevada of California can be distinguished from all shrubby forms of Quercus chrysolepis by the absence of glandular trichomes and by thin cups with small nut-attachment scars. At lower elevations in northern California and southwestern Oregon, secondary contact with Q. chrysolepis has resulted in the formation of hybrids. (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. Protobalanus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. turbinella subsp. ajoensis, Q. turbinella var. ajoensis | |
Name authority | Hittell: Resources Calif. 101. (1863) — (as vaccinifolia) | C. H. Muller: Madroño 12: 140. (1954) |
Web links |