FNA: Quercus pacifica vs. Quercus depressipes

	Quercus pacifica	Quercus depressipes
	Channel Island scrub oak, island scrub oak, Pacific oak	Davis Mountain oak, depressed oak
Habit	Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller.	Shrubs, evergreen or subevergreen, low, to 1 m, often forming dense thickets, rhizomatous.
Bark	scaly on older branches and trunk.	gray, scaly.
Twigs	brownish or reddish, minutely puberulent, becoming glabrate and gray with age.	tan-brown, becoming reddish gray, 1-1.5 mm diam., glabrate or hairy.
Buds	light or chestnut brown, ovate or globose, 2-3 × 1-2 mm.	tan or brown, subglobose, 1-1.5 mm, glabrate or scales inconspicuously ciliate.
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 oblong to elliptic, 10-25(-60) × 8-25 mm, thick, leathery, base moderately to deeply cordate, petiole strongly depressed in basal sinus, margins inconspicuously toothed in distal 1/2, rarely entire, sometimes sublobate, somewhat revolute, secondary veins 5 or 6 on each side with few intermediates, branching, apex broadly rounded to subacute; surfaces abaxially dull gray-green or glaucous, completely glabrous or with a few stellate hairs on midrib, adaxially similar to abaxial surface, secondary veins somewhat raised on both surfaces.
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.	paired on peduncle 7-15 mm; cup 4-7 mm deep × 8-13 mm wide, goblet-shaped, enclosing 1/4-1/2 nut, base somewhat constricted or rounded, scales moderately tuberculate, proximally densely gray-tomentose, tips rather closely appressed, reddish brown, abaxially glabrous, ciliate; nut tan-brown, elliptic to ovoid or globose, to 10-15 × 10-11 mm, apex rounded, glabrous.
Cotyledons	distinct.	connate.

	Quercus pacifica	Quercus depressipes
Phenology	Flowering spring.	Flowering spring.
Habitat	Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands	Grassland and open wooded slopes
Elevation	0-300 m (0-1000 ft)	2100-2600 m (6900-8500 ft)
Distribution	CA [WildflowerSearch map] [BONAP county map]	TX; Mexico (Chihuahua, Durango, and Zacatecas) [BONAP county map]
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 depressipes enters the United States in only one population on the highest portion of Mt. Livermore in trans-Pecos Texas; it has a wider distribution in the dry altiplano of northern Mexico. Its most distinctive characteristics are the combination of dwarf clonal habit, small glaucous leaves without spinose teeth, and connate cotyledons. In northern Mexico, it hybridizes locally with Q. rugosa. (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	Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii	Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pacifica, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Synonyms	Q. dumosa var. polycarpa	Q. bocoynensis
Name authority	Nixon & C. H. Muller: Novon 4: 391. (1994)	Trelease: Mem. Natl. Acad. Sci. 20: 90. (1924)
Web links	Local floras: CA Local Web sites: CalFlora, CalPhotos WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Quercus depressipes

Channel Island scrub oak, island scrub oak, Pacific oak

Davis Mountain oak, depressed oak

Habit

Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller.

Shrubs, evergreen or subevergreen, low, to 1 m, often forming dense thickets, rhizomatous.

Bark

scaly on older branches and trunk.

gray, scaly.

Twigs

brownish or reddish, minutely puberulent, becoming glabrate and gray with age.

tan-brown, becoming reddish gray, 1-1.5 mm diam., glabrate or hairy.

Buds

light or chestnut brown, ovate or globose, 2-3 × 1-2 mm.

tan or brown, subglobose, 1-1.5 mm, glabrate or scales inconspicuously ciliate.

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 oblong to elliptic, 10-25(-60) × 8-25 mm, thick, leathery, base moderately to deeply cordate, petiole strongly depressed in basal sinus, margins inconspicuously toothed in distal 1/2, rarely entire, sometimes sublobate, somewhat revolute, secondary veins 5 or 6 on each side with few intermediates, branching, apex broadly rounded to subacute;

surfaces abaxially dull gray-green or glaucous, completely glabrous or with a few stellate hairs on midrib, adaxially similar to abaxial surface, secondary veins somewhat raised on both surfaces.

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.

paired on peduncle 7-15 mm;

cup 4-7 mm deep × 8-13 mm wide, goblet-shaped, enclosing 1/4-1/2 nut, base somewhat constricted or rounded, scales moderately tuberculate, proximally densely gray-tomentose, tips rather closely appressed, reddish brown, abaxially glabrous, ciliate;

nut tan-brown, elliptic to ovoid or globose, to 10-15 × 10-11 mm, apex rounded, glabrous.

Cotyledons

distinct.

connate.

Quercus pacifica

Quercus depressipes

Phenology

Flowering spring.

Habitat

Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands

Grassland and open wooded slopes

Elevation

0-300 m (0-1000 ft)

2100-2600 m (6900-8500 ft)

Distribution

[WildflowerSearch map]

[BONAP county map]

TX; Mexico (Chihuahua, Durango, and Zacatecas)

[BONAP county map]

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 depressipes enters the United States in only one population on the highest portion of Mt. Livermore in trans-Pecos Texas; it has a wider distribution in the dry altiplano of northern Mexico. Its most distinctive characteristics are the combination of dwarf clonal habit, small glaucous leaves without spinose teeth, and connate cotyledons. In northern Mexico, it hybridizes locally with Q. rugosa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source

FNA vol. 3.

Parent taxa

Fagaceae > Quercus > sect. Quercus

Sibling taxa

Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii

Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pacifica, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii

Synonyms

Q. dumosa var. polycarpa

Q. bocoynensis

Name authority

Nixon & C. H. Muller: Novon 4: 391. (1994)

Trelease: Mem. Natl. Acad. Sci. 20: 90. (1924)

Web links

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

Choose a data source: Flora of North America

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Quercus pacifica

Quercus depressipes

Quercus pacifica

Quercus depressipes