Quercus engelmannii |
Quercus kelloggii |
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Engelmann oak, Engelmann's oak |
California black oak, Kellogg oak |
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Habit | Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed. | Trees, deciduous, to 25 m. Bark dark brown to black, ridges broad, irregular. |
Twigs | light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate. |
brown to red-brown, (1.5-)2-3.5 mm diam., glabrate. |
Buds | reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds. |
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Leaves | blade oblong to elliptic, occasionally lanceolate or ovate, (20-)30-60(-80) × (5-)10-20(-25) mm, base cuneate to cordate, margins entire, undulate, sometimes irregularly toothed, especially toward apex, secondary veins 7-8(-10) on each side, branched, apex acute or broadly rounded; surfaces abaxially blue-green or pale green, densely and loosely glandular-tomentose, quickly glabrate or persistently floccose, especially about base of midrib, at maturity strongly glaucous, adaxially gray-green or pale green, bluish green or glaucous. |
blade ovate or broadly elliptic to obovate, 60-200 × 40-140 mm, base cordate to obtuse, occasionally rounded, margins with 7-11 lobes and 13-45 awns, lobes acute to distally expanded, separated by deep sinuses, apex acute; surfaces abaxially glabrous with small axillary tufts of tomentum to densely pubescent, adaxially glabrous to minutely pubescent, veins raised on both surfaces. |
Acorns | solitary or paired, subsessile or on peduncle to 5-6 mm; cup cup-shaped or shallowly cup-shaped, 8-10 mm deep × 10-15 mm wide, enclosing 1/3 nut, scales 1.5-3 mm wide, strongly and regularly tuberculate near base of cup, gray-pubescent; nut light brown, ovoid or oblong, 15-25 × 12-14 mm, glabrate or puberulent about apex. |
biennial; cup saucer-shaped to deeply bowl-shaped, 13-27 mm high × 20-28 mm wide, covering 1/2-2/3 nut, outer surface glabrous to sparsely puberulent, inner surface 1/3 to completely pubescent, scales more than 4 mm long, attenuate or acuminate to acute, smooth, occasionally tuberculate near base of cup, tips loose, especially at margin of cup; nut oblong to broadly ellipsoid, 21-34 × 14-22 mm, puberulent, especially at apex, scar diam. 5.5-10.5 mm. |
Cotyledons | connate. |
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Terminal | buds chestnut brown, ovoid, 4-10 mm, glabrous or with scales ciliate on margins. |
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2n | = 24. |
= 24. |
Quercus engelmannii |
Quercus kelloggii |
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Phenology | Flowering in spring. | Flowering late spring. |
Habitat | Oak woodlands, margins of chaparral, arroyos, slopes and bajadas | On slopes and valleys of hills and mountains |
Elevation | 50-1200 m (200-3900 ft) | 300-2400 m (1000-7900 ft) |
Distribution |
CA; Mexico (Baja California)
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CA; OR
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Discussion | Quercus engelmannii is closely related to and possibly conspecific with Q. oblongifolia. The cups of Q. engelmannii are larger, deeper, and generally more tuberculate than those of Q. oblongifolia, and the scales are usually larger. Based on available samples, the nuts of Q. engelmannii are consistently larger than those of Q. oblongifolia, apparently with little, if any, overlap in diameter. Considerably more variation occurs within Q. engelmannii in leaf form, possibly reflecting introgression from other white oak species such as Q. cornelius-mulleri, Q. dumosa, and Q. durata (see treatment). On Catalina Island, Quercus engelmannii is known only from a small grove of trees. Putative hybrids between Q. engelmannii and Q. cornelius-mulleri are common in areas of contact between the two species in Riverside and San Diego counties in southern California. Such a population was the basis for Q. acutidens Torrey [Q. dumosa var. acutidens (Torrey) Wenzig]. Other names applied to those populations are Q. macdonaldii var. elegantula Greene and Q. dumosa var. elegantula (Greene) Jepson. Variable in leaf form and stature, those intermediates form extensive populations and are probably best disposed of under the name Q. ×acutidens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The abundant crops of acorns from Quercus kelloggii were at one time an important food source for Native Americans. The species reportedly hybridizes with Quercus agrifolia (= Q. ×ganderi C. B. Wolf) and Q. wislizenii (= Q. ×morehus Kellogg). (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. Lobatae |
Sibling taxa | ||
Synonyms | Q. californica, Q. tinctoria var. californica | |
Name authority | Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889) | Newberry: Pacif. Railr. Rep. 6: 28, 89, fig. 6. (1859) |
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