Quercus pacifica |
Quercus michauxii |
|
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Channel Island scrub oak, island scrub oak, Pacific oak |
basket oak, cow oak, swamp chestnut oak |
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Habit | Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller. | Trees, deciduous, to 20 m. Bark light brown or gray, scaly. |
Bark | scaly on older branches and trunk. |
|
Twigs | brownish or reddish, minutely puberulent, becoming glabrate and gray with age. |
brown or reddish brown, 2-3 mm diam., with sparse spreading hairs or glabrate. |
Buds | light or chestnut brown, ovate or globose, 2-3 × 1-2 mm. |
reddish brown, ovoid, apex rounded or acute, glabrous or minutely puberulent. |
Leaves | blade obovate or oblong, planar to moderately convex or undulate, 15-40 × 7-20(-40) mm, base cuneate or rounded, attenuate-decurrent along petiole, margins minutely cartilaginous, entire or with 1-5 irregular teeth on each side, secondary veins obscure, 1-5 on each side, apex blunt or rounded, occasionally subacute with mucronate tip; surfaces abaxially waxy, glandular, with scattered minute, flat, appressed, ± 8-rayed stellate hairs, not obscuring surface, adaxially green, glossy, glabrate or with minute, scattered, stellate hairs. |
blade broadly obovate or broadly elliptic, (60-)100-280 × 50-180 mm, base rounded-acuminate or broadly cuneate, margins regularly toothed, teeth rounded, dentate, or acuminate, secondary veins 15-20 on each side, parallel, straight or somewhat curved, apex broadly rounded or acuminate; surfaces abaxially light green or yellowish, felty to touch because of conspicuous or minute, erect, 1-4-rayed hairs, adaxially glabrous or with minute simple or fascicled hairs. |
Acorns | paired or solitary in leaf axil, subsessile, rarely pedunculate in teratological forms; cup hemispheric to turbinate, to 15 mm deep × 20 mm wide, enclosing only 1/4-1/2 nut, scales moderately to heavily tuberculate, irregularly formed; nut light brown, acute-cylindric or fusiform, tapered, (15-)20-30 × (6-)9-15 m, apex acute, glabrate. |
1-3, subsessile or more often on axillary peduncle to 20-30 mm; cup hemispheric, broadly hemispheric or even short-cylindric, 15-25 mm deep × 25-40 mm wide, enclosing 1/2 nut or more, scales very loosely appressed, distinct to base, gray or light brown, moderately to heavily tuberculate, tips silky-tomentose; nut light brown, ovoid or cylindric, 25-35 × 20-25 mm, glabrous. |
Cotyledons | distinct. |
distinct. |
Quercus pacifica |
Quercus michauxii |
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Phenology | Flowering spring. | Flowering early–late spring. |
Habitat | Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands | Bottomlands, rich sandy woods and swamps, on variety of soils |
Elevation | 0-300 m (0-1000 ft) | 0-600 m (0-2000 ft) |
Distribution |
CA
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AL; AR; DE; FL; GA; IL; IN; KY; LA; MD; MO; MS; NC; NJ; PA; SC; TN; TX; VA
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Discussion | Of conservation concern. Quercus pacifica is endemic on three of the California Channel Islands: Santa Cruz, Santa Catalina, and Santa Rosa. It is not known from the mainland, but it bears a superficial similarity to some of the tree forms that are putative hybrids between Q. engelmannii and Q. cornelius-mulleri in San Diego County. The latter populations, sometimes treated as Q. ×acutidens, differ in having much greater variability in leaf shape; thicker, more leathery leaves; denser abaxial leaf vestiture; much smaller hairs, having more than 10 rays; and variable levels of connation of cotyledons (always distinct in Q. pacifica). Quercus pacifica appears to be most closely related to Q. douglasii, whether by direct descent or by introgression with another species no longer extant on the islands. Quercus ×macdonaldii Greene (as a species) [= Quercus dumosa var. macdonaldii (Greene) Jepson] is a stabilized hybrid complex between Quercus pacifica and Q. lobata Née. The plants tend to be small to moderate trees with leaves that resemble those of Q. lobata; the leaves are much more shallowly lobed and always less than two-thirds the distance from the margin to the midrib. Quercus ×macdonaldii is known from Santa Rosa, Santa Cruz, and Santa Catalina islands. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Quercus michauxii is easily distinguished from other chestnut-leaved oaks by the felty hairs of the abaxial leaf surface and rather large acorn cups with attenuate-acute, loose scales. This species is no longer extant in Oklahoma. Historical reports from Connecticut, Massachusetts, and New York have not been confirmed; possibly populations are no longer extant. (See Quercus montana for a discussion of nomenclature and the uncertain application of the name Q. prinus). (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. dumosa var. polycarpa | Q. houstoniana |
Name authority | Nixon & C. H. Muller: Novon 4: 391. (1994) | Nuttall: Gen. N. Amer. Pl. 2: 215. (1818) |
Web links |