FNA: Quercus engelmannii vs. Quercus rugosa

	Quercus engelmannii	Quercus rugosa
	Engelmann oak, Engelmann's oak	netleaf oak
Habit	Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed.	Shrubs or trees, evergreen, usually moderate-sized, rarely large.
Bark		light or dark brown, scaly.
Twigs	light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate.	brown, turning gray with age, 1-2 mm diam., tomentose to tomentulose, variously glabrate or persistently pubescent.
Buds	reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds.	brown, ovoid, 2-4 mm, apex obtuse, sparsely pubescent or eventually glabrate.
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 broadly obovate or panduriform to orbiculate or elliptic, rarely narrowly obovate, usually cupped, strongly concave proximally, sometimes planar, to 100 × 70 mm, stiff, leathery, base deeply or shallowly cordate, margins usually somewhat revolute, cartilaginously thickened, undulately crisped or flat with inconspicuous or coarse mucronate teeth near apex, secondary veins 8-10(-12) on each side, branched, apex broadly rounded, rarely subacute; surfaces abaxially dull, glaucous, or densely brownish tomentose, becoming nearly glabrate or pubescence persistent, especially about midribs, secondary veins very prominently raised, reticulate, adaxially dark green, lustrous, sparsely stellate-pubescent especially about base of midrib, secondary veins impressed.
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.	1-3 or more on slender axillary peduncle 30-60 mm; cup deeply cup-shaped to saucer-shaped, to 9 mm deep × 15 mm wide, enclosing to 1/2 nut, scales loosely appressed, characteristically somewhat spreading, brown, ovate, tuberculate-thickened or only slightly so, tomentose or obscurely tomentulose; nut light brown, ovoid to elliptic, to 20 × 15 mm, glabrous or minutely villous.
Cotyledons	connate.	distinct, often reddish or purple.
2n	= 24.

	Quercus engelmannii	Quercus rugosa
Phenology	Flowering in spring.	Flowering early–late spring.
Habitat	Oak woodlands, margins of chaparral, arroyos, slopes and bajadas	Wooded slopes
Elevation	50-1200 m (200-3900 ft)	2000-2500 m (6600-8200 ft)
Distribution	CA; Mexico (Baja California) [WildflowerSearch map] [BONAP county map]	AZ; NM; TX; Mexico; Central America (Guatemala) [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.)	Quercus rugosa occurs on wooded slopes at high elevations in trans-Pecos Texas, southern New Mexico, and Arizona, and throughout most of the mesic montane parts of Mexico, south to Guatemala. (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. 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. ariifolia, Q. diversicolor, Q. durangensis, Q. reticulata, Q. rhodophlebia, Q. vellifera
Name authority	Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889)	Nee.: Anales Ci. Nat. 3: 275. (1801)
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 rugosa

Engelmann oak, Engelmann's oak

netleaf oak

Habit

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

Shrubs or trees, evergreen, usually moderate-sized, rarely large.

Bark

light or dark brown, scaly.

Twigs

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

brown, turning gray with age, 1-2 mm diam., tomentose to tomentulose, variously glabrate or persistently pubescent.

Buds

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

stipules persistent about terminal buds.

brown, ovoid, 2-4 mm, apex obtuse, sparsely pubescent or eventually glabrate.

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 broadly obovate or panduriform to orbiculate or elliptic, rarely narrowly obovate, usually cupped, strongly concave proximally, sometimes planar, to 100 × 70 mm, stiff, leathery, base deeply or shallowly cordate, margins usually somewhat revolute, cartilaginously thickened, undulately crisped or flat with inconspicuous or coarse mucronate teeth near apex, secondary veins 8-10(-12) on each side, branched, apex broadly rounded, rarely subacute;

surfaces abaxially dull, glaucous, or densely brownish tomentose, becoming nearly glabrate or pubescence persistent, especially about midribs, secondary veins very prominently raised, reticulate, adaxially dark green, lustrous, sparsely stellate-pubescent especially about base of midrib, secondary veins impressed.

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.

1-3 or more on slender axillary peduncle 30-60 mm;

cup deeply cup-shaped to saucer-shaped, to 9 mm deep × 15 mm wide, enclosing to 1/2 nut, scales loosely appressed, characteristically somewhat spreading, brown, ovate, tuberculate-thickened or only slightly so, tomentose or obscurely tomentulose;

nut light brown, ovoid to elliptic, to 20 × 15 mm, glabrous or minutely villous.

Cotyledons

connate.

distinct, often reddish or purple.

= 24.

Quercus engelmannii

Quercus rugosa

Phenology

Flowering in spring.

Flowering early–late spring.

Habitat

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

Wooded slopes

Elevation

50-1200 m (200-3900 ft)

2000-2500 m (6600-8200 ft)

Distribution

CA; Mexico (Baja California)

[WildflowerSearch map]

[BONAP county map]

AZ; NM; TX; Mexico; Central America (Guatemala)

[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.)

Quercus rugosa occurs on wooded slopes at high elevations in trans-Pecos Texas, southern New Mexico, and Arizona, and throughout most of the mesic montane parts of Mexico, south to Guatemala.

(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. 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. ariifolia, Q. diversicolor, Q. durangensis, Q. reticulata, Q. rhodophlebia, Q. vellifera

Name authority

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

Nee.: Anales Ci. Nat. 3: 275. (1801)

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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Flora of North America species comparison

Quercus engelmannii

Quercus rugosa

Quercus engelmannii

Quercus rugosa