FNA: Quercus pacifica vs. Quercus john-tuckeri

	Quercus pacifica	Quercus john-tuckeri
	Channel Island scrub oak, island scrub oak, Pacific oak	desert scrub oak, Tucker oak, Tucker's oak
Habit	Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller.	Shrubs, subevergreen or evergreen, 1-3(-5) m. Bark light gray or brown, scaly.
Bark	scaly on older branches and trunk.
Twigs	brownish or reddish, minutely puberulent, becoming glabrate and gray with age.	yellowish or dingy gray, 1-1.5(-2) mm diam., densely tomentulose.
Buds	light or chestnut brown, ovate or globose, 2-3 × 1-2 mm.	brown, ovoid or globose, 1.5-2(-3) mm, glabrous except for ciliate margins of scales; proximal scales often yellowish 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 unicolored, elliptic or obovate, (10-)15-30(-40) × (8-)10-15(-20) mm, thick and leathery, often brittle, base truncate or rounded-attenuate, rarely subcordate, margins irregularly spinose-toothed, occasionally shallowly lobate, secondary veins (3-)4-7, often some veins branching near margin and passing into more than 1 tooth, apex acute or rounded; surfaces abaxially waxy grayish, light green, or yellowish, sparse to moderately dense (8-)10-12-rayed, (loosely) appressed-stellate hairs, often 0.2-0.5 mm diam., and sparse to crowded, yellowish, glandular hairs, adaxially dull grayish, with stellate hairs, similar to abaxial surface.
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; cup cup-shaped or obconic to hemispheric, 5-7 mm deep × 10-15 mm wide, thin, scales whitish or yellowish, moderately or scarcely tuberculate, puberulent; nut fusiform, ovoid, or conic, 20-30 mm, apex acute.
Cotyledons	distinct.	distinct.

	Quercus pacifica	Quercus john-tuckeri
Phenology	Flowering spring.
Habitat	Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands	Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush
Elevation	0-300 m (0-1000 ft)	900-2000 m (3000-6600 ft)
Distribution	CA [WildflowerSearch map] [BONAP county map]	CA [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.)	Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush; 900-2000 m; Calif. Endemic to California, Quercus john-tuckeri occurs from Los Angeles County northward in the interior Coast Ranges and Sierra Foothills to the northern edge of Sacramento Valley. Quercus john-tuckeri bears some resemblance to both Q. turbinella and Q. berberidifolia. Quercus turbinella has pedunculate fruit and cordate leaf bases, however, and Q. berberidifolia has a glabrate adaxial leaf surface, substantially smaller stellate trichomes with fewer rays on the abaxial leaf surface, heavier tuberculate acorn cups, and blunt or rounded (instead of acute) acorns. (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. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, 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. turbinella subsp. californica
Name authority	Nixon & C. H. Muller: Novon 4: 391. (1994)	Nixon & C. H. Muller: Novon 4: 391. (1994)
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	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

Quercus john-tuckeri

Channel Island scrub oak, island scrub oak, Pacific oak

desert scrub oak, Tucker oak, Tucker's oak

Habit

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

Shrubs, subevergreen or evergreen, 1-3(-5) m. Bark light gray or brown, scaly.

Bark

scaly on older branches and trunk.

Twigs

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

yellowish or dingy gray, 1-1.5(-2) mm diam., densely tomentulose.

Buds

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

brown, ovoid or globose, 1.5-2(-3) mm, glabrous except for ciliate margins of scales;

proximal scales often yellowish 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 unicolored, elliptic or obovate, (10-)15-30(-40) × (8-)10-15(-20) mm, thick and leathery, often brittle, base truncate or rounded-attenuate, rarely subcordate, margins irregularly spinose-toothed, occasionally shallowly lobate, secondary veins (3-)4-7, often some veins branching near margin and passing into more than 1 tooth, apex acute or rounded;

surfaces abaxially waxy grayish, light green, or yellowish, sparse to moderately dense (8-)10-12-rayed, (loosely) appressed-stellate hairs, often 0.2-0.5 mm diam., and sparse to crowded, yellowish, glandular hairs, adaxially dull grayish, with stellate hairs, similar to abaxial surface.

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;

cup cup-shaped or obconic to hemispheric, 5-7 mm deep × 10-15 mm wide, thin, scales whitish or yellowish, moderately or scarcely tuberculate, puberulent;

nut fusiform, ovoid, or conic, 20-30 mm, apex acute.

Cotyledons

distinct.

Quercus pacifica

Quercus john-tuckeri

Phenology

Flowering spring.

Habitat

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

Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush

Elevation

0-300 m (0-1000 ft)

900-2000 m (3000-6600 ft)

Distribution

[WildflowerSearch map]

[BONAP county map]

[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.)

Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush; 900-2000 m; Calif.

Endemic to California, Quercus john-tuckeri occurs from Los Angeles County northward in the interior Coast Ranges and Sierra Foothills to the northern edge of Sacramento Valley.

Quercus john-tuckeri bears some resemblance to both Q. turbinella and Q. berberidifolia. Quercus turbinella has pedunculate fruit and cordate leaf bases, however, and Q. berberidifolia has a glabrate adaxial leaf surface, substantially smaller stellate trichomes with fewer rays on the abaxial leaf surface, heavier tuberculate acorn cups, and blunt or rounded (instead of acute) acorns.

(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. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, 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. turbinella subsp. californica

Name authority

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

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 john-tuckeri

Quercus pacifica

Quercus john-tuckeri