FNA: Quercus pacifica vs. Quercus grisea

	Quercus pacifica	Quercus grisea
	Channel Island scrub oak, island scrub oak, Pacific oak	gray oak
Habit	Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller.
Bark	scaly on older branches and trunk.
Twigs	brownish or reddish, minutely puberulent, becoming glabrate and gray with age.	gray, 1-2 mm diam., sparsely or densely stellate-tomentulose or tomentose when young.
Buds	light or chestnut brown, ovate or globose, 2-3 × 1-2 mm.	dark red-brown, ovoid to subglobose, 1-2 mm, stellate hairs causing yellowish color, at least on outer scales; stipules persistent, 1-4, subulate, pubescent, at base of terminal buds.
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 or ovate, (15-)25-35(-80) × (7-)15-30(-40) mm, thick and leathery, base cordate or rounded, margins minutely revolute, entire or dentate with mucronate teeth, secondary veins 6-10 on each side, branched, apex acute, sometimes obtuse, rarely rounded; surfaces abaxially dull gray-green or yellowish, minutely stellate-pubescent with interlocking hairs, secondary veins very prominent, adaxially dull green, very sparsely and minutely stellate-pubescent, secondary veins slightly raised.
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.	solitary or paired, subsessile or on peduncle 0-30 mm; cup from deeply goblet- to deeply cup-shaped, 4-10 mm deep × 8-15 mm wide, enclosing to 1/2 nut, scales broadly ovate to oblong, proximal scales slightly or markedly tuberculate and whitish canescent, tips closely appressed, red-brown, thin, glabrate; nut light brown, ovoid to narrowly ovoid or ellipsoid, 12-18 × 8-12 mm.
Cotyledons	distinct.	connate.
Large		shrubs or moderate trees, deciduous or subevergreen, to 10 m. Bark gray, fissured.

	Quercus pacifica	Quercus grisea
Phenology	Flowering spring.	Flowering spring.
Habitat	Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands	Igneous or dolomitic slopes, oak woodlands, juniper woodlands, desert chaparral
Elevation	0-300 m (0-1000 ft)	usually above 1500 m (usually above 4900 ft)
Distribution	CA [WildflowerSearch map] [BONAP county map]	AZ; NM; TX; Mexico (Sonora, Chihuahua, and Durango) [WildflowerSearch map] [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.)	Some of the specimens referred to Quercus endemica by C. H. Muller should be placed in Q. grisea. Numerous hybrids between Quercus grisea and other white oaks, including Q. gambelii, Q. mohriana, Q. arizonica, and numerous species in northern Mexico, have been reported. In the Hueco and Quitman mountains of trans-Pecos Texas, putative hybrids of Q. grisea × Q. turbinella Greene occur. (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. 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. 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. undulata var. grisea
Name authority	Nixon & C. H. Muller: Novon 4: 391. (1994)	Liebmann: Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 171. (1854)
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 grisea

Channel Island scrub oak, island scrub oak, Pacific oak

gray oak

Habit

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

Bark

scaly on older branches and trunk.

Twigs

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

gray, 1-2 mm diam., sparsely or densely stellate-tomentulose or tomentose when young.

Buds

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

dark red-brown, ovoid to subglobose, 1-2 mm, stellate hairs causing yellowish color, at least on outer scales;

stipules persistent, 1-4, subulate, pubescent, at base of terminal buds.

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 or ovate, (15-)25-35(-80) × (7-)15-30(-40) mm, thick and leathery, base cordate or rounded, margins minutely revolute, entire or dentate with mucronate teeth, secondary veins 6-10 on each side, branched, apex acute, sometimes obtuse, rarely rounded;

surfaces abaxially dull gray-green or yellowish, minutely stellate-pubescent with interlocking hairs, secondary veins very prominent, adaxially dull green, very sparsely and minutely stellate-pubescent, secondary veins slightly raised.

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.

solitary or paired, subsessile or on peduncle 0-30 mm;

cup from deeply goblet- to deeply cup-shaped, 4-10 mm deep × 8-15 mm wide, enclosing to 1/2 nut, scales broadly ovate to oblong, proximal scales slightly or markedly tuberculate and whitish canescent, tips closely appressed, red-brown, thin, glabrate;

nut light brown, ovoid to narrowly ovoid or ellipsoid, 12-18 × 8-12 mm.

Cotyledons

distinct.

connate.

Large

shrubs or moderate trees, deciduous or subevergreen, to 10 m. Bark gray, fissured.

Quercus pacifica

Quercus grisea

Phenology

Flowering spring.

Habitat

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

Igneous or dolomitic slopes, oak woodlands, juniper woodlands, desert chaparral

Elevation

0-300 m (0-1000 ft)

usually above 1500 m (usually above 4900 ft)

Distribution

[WildflowerSearch map]

[BONAP county map]

AZ; NM; TX; Mexico (Sonora, Chihuahua, and Durango)

[WildflowerSearch map]

[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.)

Some of the specimens referred to Quercus endemica by C. H. Muller should be placed in Q. grisea.

Numerous hybrids between Quercus grisea and other white oaks, including Q. gambelii, Q. mohriana, Q. arizonica, and numerous species in northern Mexico, have been reported. In the Hueco and Quitman mountains of trans-Pecos Texas, putative hybrids of Q. grisea × Q. turbinella Greene occur.

(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. 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. 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. undulata var. grisea

Name authority

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

Liebmann: Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 171. (1854)

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 grisea

Quercus pacifica

Quercus grisea