Quercus engelmannii |
Quercus berberidifolia |
|
---|---|---|
Engelmann oak, Engelmann's oak |
California scrub oak, inland scrub oak, scrub oak |
|
Habit | Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed. | Shrubs, subevergreen, 1-2(-4) m. Bark gray, scaly. |
Twigs | light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate. |
gray, yellowish, rarely reddish, 1-3 mm diam. |
Buds | reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds. |
reddish brown, globose or ovoid, 2-3 mm, minutely puberulent. |
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 bicolored, obovate, elliptic, occasionally subrotund, planar or moderately convex, (10-)15-30 × (8-)10-20 mm, base truncate or rounded-attenuate, rarely cuneate, margins irregularly toothed and spinose, often sublobate, rarely entire, secondary veins (3-)4-7 on each side, apex broadly rounded or acute; surfaces abaxially waxy, light green or glaucous, with scattered minute, appressed, (4-)8(-10)-rayed hairs less than 0.2 mm diam. and sparse to dense yellowish, glandular hairs, adaxially glossy or dull green, glabrous or glabrate. |
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. |
solitary or paired, subsessile; cup hemispheric or turbinate, rarely shallowly cup-shaped, rim thick, 8-15 mm deep × 15-20(-22) mm wide, enclosing to 1/2 nut, scales reddish or yellowish, usually strongly, irregularly tuberculate, puberulent or canescent; nut light to dark brown, ovoid, ellipsoid, or barrel-shaped, (10-)15-30 × (8-)10-20 mm, apex rounded, glabrous at maturity. |
Cotyledons | connate. |
distinct. |
2n | = 24. |
|
Quercus engelmannii |
Quercus berberidifolia |
|
Phenology | Flowering in spring. | Flowering spring. |
Habitat | Oak woodlands, margins of chaparral, arroyos, slopes and bajadas | Chaparral, margins of coastal sage scrub |
Elevation | 50-1200 m (200-3900 ft) | 100-1800 m (300-5900 ft) |
Distribution |
CA; Mexico (Baja California)
|
CA
|
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 name Quercus dumosa (see species treatment no. 72) has often been applied to this species. Quercus berberidifolia is the most common scrub oak of central and southern California, mostly at midelevations in the Coast Ranges. In central California it is replaced in drier interior habitats by Q. john-tuckeri, and south of the transverse ranges by Q. cornelius-mulleri. From Santa Barbara south, it does not descend to the low elevation coastal sites typical of Q. dumosa in the strict sense. Quercus berberidifolia hybridizes with numerous other white oaks of California. In southern California, putative hybrids with Q. john-tuckeri are noticeable in the mountains above Ventura and on the north slope of the Tehachapi Mountains. (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. agrifolia var. berberidifolia, Q. dumosa var. munita | |
Name authority | Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889) | Liebmann: Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 172. (1854) |
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