Quercus vacciniifolia |
Quercus robusta |
|
---|---|---|
huckleberry oak |
robust oak |
|
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. | Trees, deciduous, to 13 m. Bark brown or black, roughly furrowed. |
Twigs | dark reddish brown, 1.5-2.5 mm diam., densely pubescent or glabrate. |
|
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. |
blade acutely ovate to elliptic, widest at or proximal to middle, 55-120 × 20-50 mm, base cuneate to rounded or subcordate, margins with 6-8 teeth or shallow lobes with rounded sinuses, rarely entire, 1-10 awns, apex acute or attenuate; surfaces abaxially glabrous except for small axillary tufts of tomentum or pubescent along midrib, adaxially glabrous or persistently pubescent near base and along midrib. |
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. |
biennial; cup deeply cup-shaped, 6-9 mm high × 8-12 mm wide, covering 1/4-1/3 nut, outer surface puberulent or glabrate, inner surface uniformly pubescent, scales tightly appressed, acute or attenuate; nut oblong to broadly ellipsoid, 10-22 × 7-10 mm, glabrate, scar diam. 3.5-4.5 mm. |
Terminal | buds conic, 2.5 mm, scales brown with ciliate margins. |
buds glossy light brown, acutely ovoid, 4-7 mm, glabrous or pubescent on apical 1/2. |
Quercus vacciniifolia |
Quercus robusta |
|
Phenology | Flowering in early summer. | Flowering spring. |
Habitat | Dry ridges, steep slopes, and rocky areas from montane coniferous zone to near treeline | Moist wooded canyons in Chisos Mountains |
Elevation | 900-2800 m (3000-9200 ft) | 1500 m (4900 ft) |
Distribution |
CA; NV; OR
|
TX |
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.) |
Of conservation concern. After describing this species, C. H. Muller later (1951, 1970) concluded that it represented a hybrid between Quercus emoryi and Q. gravesii. The extreme forms (e.g., the type specimens) of Q. robusta and Q. gravesii are easily differentiated, but these two taxa appear to occupy the ends of a morphologic continuum. Muller's recent view, however, is that Q. robusta deserves species status. The origin of this taxon is still worthy of study. (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. Lobatae |
Sibling taxa | ||
Name authority | Hittell: Resources Calif. 101. (1863) — (as vaccinifolia) | C. H. Muller: Torreya 34: 119. (1934) |
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