FNA: Quercus engelmannii vs. Quercus turbinella

	Quercus engelmannii	Quercus turbinella
	Engelmann oak, Engelmann's oak	grey oak, shrub live oak, Sonoran scrub oak, turbinella oak
Habit	Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed.	Shrubs or small trees, evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly.
Twigs	light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate.	brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate.
Buds	reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds.	brown, round to ovoid, 1-2 mm, minutely pubescent.
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 elliptic or ovate, (1.5-)20-30 × (5-)10-15(-20) mm, thick, leathery, base cordate or rounded, margins planar or slightly crisped-undulate, coarsely 3-5-toothed or very shallowly lobed on each side, teeth spinose with spines 1-1.5 mm, secondary veins 4-8 on each side, apex acute or obtuse; surfaces abaxially yellow or reddish, usually glaucous, minutely stellate-puberulent, adaxially grayish, glaucous, or yellowish glandular, glabrous or sparsely and minutely stellate-pubescent.
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 several, on axillary peduncle 10-40 mm; cup hemispheric or shallowly cup-shaped, 4-6 mm deep × 8-12 mm wide, covering 1/4-1/2 nut, scales tightly appressed, ovate, moderately tuberculate, grayish or yellowish puberulent; nut light brown, ovoid, to 20 × 11 mm, minutely puberulent or glabrate.
Cotyledons	connate.	distinct.
2n	= 24.

	Quercus engelmannii	Quercus turbinella
Phenology	Flowering in spring.	Flowering spring.
Habitat	Oak woodlands, margins of chaparral, arroyos, slopes and bajadas	Dry desert slopes, often in juniper and pinyon woodlands
Elevation	50-1200 m (200-3900 ft)	800-2000 m (2600-6600 ft)
Distribution	CA; Mexico (Baja California) [WildflowerSearch map] [BONAP county map]	AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Sonora, and probably n Chihuahua) [WildflowerSearch map] [BONAP county map]
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.)	Formerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Q. turbinella. Quercus john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q. turbinella. The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q. john-tuckeri shares at least as many characteristics with Q. berberidifolia as with Q. turbinella. Thus, treatment of these two taxa as varieties of the same species is inappropriate. Quercus turbinella forms putative hybrid swarms with Q. gambelii (see treatment), as well as with Q. grisea. (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. 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	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. 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. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Synonyms		Q. dumosa var. turbinella, Q. subturbinella
Name authority	Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889)	Greene: Ill. W. Amer. Oaks 1: 37. (1889)
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, SW CO Wildflowers WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Quercus turbinella

Engelmann oak, Engelmann's oak

grey oak, shrub live oak, Sonoran scrub oak, turbinella oak

Habit

Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed.

Shrubs or small trees, evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly.

Twigs

light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate.

brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate.

Buds

reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent;

stipules persistent about terminal buds.

brown, round to ovoid, 1-2 mm, minutely pubescent.

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 elliptic or ovate, (1.5-)20-30 × (5-)10-15(-20) mm, thick, leathery, base cordate or rounded, margins planar or slightly crisped-undulate, coarsely 3-5-toothed or very shallowly lobed on each side, teeth spinose with spines 1-1.5 mm, secondary veins 4-8 on each side, apex acute or obtuse;

surfaces abaxially yellow or reddish, usually glaucous, minutely stellate-puberulent, adaxially grayish, glaucous, or yellowish glandular, glabrous or sparsely and minutely stellate-pubescent.

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 several, on axillary peduncle 10-40 mm;

cup hemispheric or shallowly cup-shaped, 4-6 mm deep × 8-12 mm wide, covering 1/4-1/2 nut, scales tightly appressed, ovate, moderately tuberculate, grayish or yellowish puberulent;

nut light brown, ovoid, to 20 × 11 mm, minutely puberulent or glabrate.

Cotyledons

connate.

distinct.

= 24.

Quercus engelmannii

Quercus turbinella

Phenology

Flowering in spring.

Flowering spring.

Habitat

Oak woodlands, margins of chaparral, arroyos, slopes and bajadas

Dry desert slopes, often in juniper and pinyon woodlands

Elevation

50-1200 m (200-3900 ft)

800-2000 m (2600-6600 ft)

Distribution

CA; Mexico (Baja California)

[WildflowerSearch map]

[BONAP county map]

AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Sonora, and probably n Chihuahua)

[WildflowerSearch map]

[BONAP county map]

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.)

Formerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Q. turbinella. Quercus john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q. turbinella. The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q. john-tuckeri shares at least as many characteristics with Q. berberidifolia as with Q. turbinella. Thus, treatment of these two taxa as varieties of the same species is inappropriate.

Quercus turbinella forms putative hybrid swarms with Q. gambelii (see treatment), as well as with Q. grisea.

(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. 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

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. 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. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii

Synonyms

Q. dumosa var. turbinella, Q. subturbinella

Name authority

Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889)

Greene: Ill. W. Amer. Oaks 1: 37. (1889)

Web links

Local floras: CA
Local Web sites: CalFlora, CalPhotos, SW CO Wildflowers
WildflowerSearch
iNaturalist (observations)
USDA Plants Database
LBJ Wildflower Center
SEINet
Plants of the World Online
Encyclopedia of Life
Wikipedia
Google Image Search

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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Flora of North America species comparison

Quercus engelmannii

Quercus turbinella

Quercus engelmannii

Quercus turbinella