FNA: Quercus engelmannii vs. Quercus marilandica

	Quercus engelmannii	Quercus marilandica
	Engelmann oak, Engelmann's oak	blackjack oak
Habit	Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed.	Trees, deciduous, to 15 m. Bark almost black, with irregular or rectangular blocks, inner bark orangish.
Twigs	light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate.	ashy brown, (1-)2-4(-5) mm diam., pubescent to tomentose.
Buds	reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds.
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 obovate to obtrullate, (50-)70-200 × (40-)70-200 mm, base rounded or cordate, blade not decurrent, margins with 3-5 shallow, often very broad lobes and 3-10 awns, apex acute to obtuse, rarely rounded; surfaces abaxially scurfy or with scattered pubescence, adaxially glossy, glabrous, secondary veins raised on both surfaces.
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.	biennial; cup turbinate, 6-10 mm high × 13-18 mm wide, covering 1/3 nut, outer surface puberulent, inner surface pubescent, scale tips loose, especially at margin of cup, acute or acuminate; nut broadly ovoid or ellipsoid, 12-20 × 10-18 mm, often striate, glabrate, scar diam. 5-8 mm.
Cotyledons	connate.
Terminal		buds conic or narrowly ovoid-ellipsoid, 5-10 mm, noticeably 5-angled in cross section, tawny pubescent.
[r.
c		.
Friesner		1930. J. W.
Duffield		(1940) suggested that Friesner was counting bivalents; if so, then 2n = 24, consistent with all other reports for Quercus.]
2n	= 24.	= 12.

	Quercus engelmannii	Quercus marilandica
Phenology	Flowering in spring.	Flowering spring.
Habitat	Oak woodlands, margins of chaparral, arroyos, slopes and bajadas	Poor shallow soils of glades, barrens and flatwoods, disturbed fields, rocky outcrops, and dry ridges
Elevation	50-1200 m (200-3900 ft)	0-900 m (0-3000 ft)
Distribution	CA; Mexico (Baja California) [WildflowerSearch map] [BONAP county map]	AL; AR; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MD; MO; MS; NC; NE; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV [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.)	Evidence suggests that small trees from the western portion of the range (primarily Texas and Oklahoma) should be recognized as Quercus marilandica Münchhausen var. ashei Sudworth (D. M. Hunt 1989). These trees are characterized by 50-70 × 40-60 mm leaf blades with abaxial surfaces gray-tomentose in vein axils. Quercus marilandica reportedly hybridizes with Q. buckleyi and Q. falcata (E. J. Palmer 1948); and with Q. georgiana, Q. ilicifolia (= Q. ×brittoni W. T. Davis), Q. imbricaria [= Q. ×tridentata (A. de Candolle) Engelmann], Q. incana, Q. nigra, Q. phellos (Q. ×rudkini Britton), and Q. velutina (= Q. ×bushii Sargent). D. M. Hunt (1989) cited evidence of hybridization also with Q. arkansana, Q. hemisphaerica, Q. laevis, Q. laurifolia, Q. myrtifolia, Q. palustris, and Q. rubra. The Choctaw used Quercus marilandica to ease cramps and to aid in childbirth (D. E. Moerman 1986). (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. Lobatae
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. 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
Name authority	Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889)	Münchhausen: Hausvater 5(1): 253. (1770)
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 Web sites: IL Wildflowers, KS Wildflowers, LA Plants, MD Biodiversity, MO Plants WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Quercus marilandica

Engelmann oak, Engelmann's oak

blackjack oak

Habit

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

Trees, deciduous, to 15 m. Bark almost black, with irregular or rectangular blocks, inner bark orangish.

Twigs

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

ashy brown, (1-)2-4(-5) mm diam., pubescent to tomentose.

Buds

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

stipules persistent about terminal buds.

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 obovate to obtrullate, (50-)70-200 × (40-)70-200 mm, base rounded or cordate, blade not decurrent, margins with 3-5 shallow, often very broad lobes and 3-10 awns, apex acute to obtuse, rarely rounded;

surfaces abaxially scurfy or with scattered pubescence, adaxially glossy, glabrous, secondary veins raised on both surfaces.

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.

biennial;

cup turbinate, 6-10 mm high × 13-18 mm wide, covering 1/3 nut, outer surface puberulent, inner surface pubescent, scale tips loose, especially at margin of cup, acute or acuminate;

nut broadly ovoid or ellipsoid, 12-20 × 10-18 mm, often striate, glabrate, scar diam. 5-8 mm.

Cotyledons

connate.

Terminal

buds conic or narrowly ovoid-ellipsoid, 5-10 mm, noticeably 5-angled in cross section, tawny pubescent.

[r.

Friesner

1930. J. W.

Duffield

(1940) suggested that Friesner was counting bivalents;

if so, then 2n = 24, consistent with all other reports for Quercus.]

= 24.

= 12.

Quercus engelmannii

Quercus marilandica

Phenology

Flowering in spring.

Flowering spring.

Habitat

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

Poor shallow soils of glades, barrens and flatwoods, disturbed fields, rocky outcrops, and dry ridges

Elevation

50-1200 m (200-3900 ft)

0-900 m (0-3000 ft)

Distribution

CA; Mexico (Baja California)

[WildflowerSearch map]

[BONAP county map]

AL; AR; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MD; MO; MS; NC; NE; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV

[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.)

Evidence suggests that small trees from the western portion of the range (primarily Texas and Oklahoma) should be recognized as Quercus marilandica Münchhausen var. ashei Sudworth (D. M. Hunt 1989). These trees are characterized by 50-70 × 40-60 mm leaf blades with abaxial surfaces gray-tomentose in vein axils.

Quercus marilandica reportedly hybridizes with Q. buckleyi and Q. falcata (E. J. Palmer 1948); and with Q. georgiana, Q. ilicifolia (= Q. ×brittoni W. T. Davis), Q. imbricaria [= Q. ×tridentata (A. de Candolle) Engelmann], Q. incana, Q. nigra, Q. phellos (Q. ×rudkini Britton), and Q. velutina (= Q. ×bushii Sargent). D. M. Hunt (1989) cited evidence of hybridization also with Q. arkansana, Q. hemisphaerica, Q. laevis, Q. laurifolia, Q. myrtifolia, Q. palustris, and Q. rubra.

The Choctaw used Quercus marilandica to ease cramps and to aid in childbirth (D. E. Moerman 1986).

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

Source

FNA vol. 3.

Parent taxa

Fagaceae > Quercus > sect. Quercus

Fagaceae > Quercus > sect. Lobatae

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. 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

Name authority

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

Münchhausen: Hausvater 5(1): 253. (1770)

Web links

Local Web sites: IL Wildflowers, KS Wildflowers, LA Plants, MD Biodiversity, MO Plants
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 marilandica

Quercus engelmannii

Quercus marilandica