Flora of North America species comparison

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Quercus arizonica

Quercus stellata

Arizona oak, Arizona white oak

post oak
Habit Trees, evergreen or subevergreen, small to moderate-sized trees, rarely to 18 m. Bark scaly. Trees, deciduous, to 20(-30) m. Bark light gray, scaly.
Twigs

yellowish, 1.5-2.5 mm diam., persistently felty-tomentose, eventually dingy gray.

yellowish or grayish, (2-)3-5 mm diam., densely stellate-pubescent.
Buds

dull russet-brown, ovoid, distally subacute or rounded, 3 mm, sparsely pubescent or glabrate.

reddish brown, ovoid, to 4 mm, apex obtuse or acute, sparsely pubescent.
Leaves

blade elliptic or oblong to narrowly obovate or oblanceolate, planar or moderately convex, to (30-)40-80(-90) × 15-30 mm, thick and leathery, usually stiff, base cordate or rounded and weakly cordate, margins entire or coarsely toothed especially near apex, cartilaginously revolute, teeth mucronate-tipped, obscure or prominent, secondary veins ca. 7-11 on each side, branching, passing into teeth when present, apex acute to usually obtuse or broadly rounded;

surfaces abaxially dull, sparsely pubescent or subtomentose with curly branched hairs, reticulate from prominent, raised secondary veins, usually glaucous where exposed, adaxially dark or bluish green, moderately lustrous, sparsely and minutely stellate-pubescent, secondary veins slightly raised or prominent within depressions or impressed.

blade obovate to narrowly obovate, elliptic or obtriangular, 40-150(-200) × 20-100(-120) mm, rather stiff and hard, base rounded-attenuate to cordate, sometimes cuneate, margins shallowly to deeply lobed, lobes rounded or spatulate, usually distal 2 lobes divergent at right angles to midrib in cruciform pattern, secondary veins 3-5 on each side, apex broadly rounded;

surfaces abaxially yellowish green, with crowded yellowish glandular hairs and scattered minute, 6-8-rayed, appressed or semi-appressed stellate hairs, not velvety to touch, adaxially dark or yellowish green, dull or glossy, sparsely stellate, often somewhat sandpapery with harsh hairs.
Acorns

solitary or paired, subsessile, occasionally on peduncle to 15 mm;

cup hemispheric or cup-shaped, 5-10(-15) mm deep × 10-15 mm wide, enclosing ca. 1/2 nut, base rounded, margin rather coarse, scales cream to brown, broadly ovate, evenly and strongly tuberculate, tomentose, tips closely appressed;

nut light brown, ovoid or oblong, 8-12 mm, nearly glabrous.

1-3, subsessile or on peduncle to 6(-40) mm;

cup deeply saucer-shaped, proximally rounded or constricted, 7-12(-18) mm deep × (7-)10-15(-25) mm wide, enclosing 1/4-2/3 nut, scales tightly appressed, finely grayish pubescent;

nut light brown, ovoid or globose, 10-20 × 8-12(-20) mm, glabrous or finely puberulent.
Cotyledons

connate.

distinct.

Quercus arizonica

Quercus stellata
Phenology Flowering spring. Flowering spring.
Habitat Oak and pinyon woodlands, margins of chaparral, arroyos Usually on xeric sites, dry gravelly and sandy ridges and uplands, dry clays, prairies and limestone hills, woodlands and deciduous forests
Elevation 1300-2500(-3000) m (4300-8200(-9800) ft) 0-750 m (0-2500 ft)
Distribution
from FNA
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, and Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MO; MS; NC; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; WV
[WildflowerSearch map]
[BONAP county map]
Discussion

Some of the specimens previously referred to Quercus endemica by C. H. Muller belong here instead.

Putative hybrids between Quercus arizonica and Q. grisea (= Q. ×organensis Trelease) are problematic in local areas of contact from southeastern Arizona to western Texas. These intermediates tend to have narrower leaves than Q. arizonica, with moderately reticulate patterns of venation, and more densely hairy leaves. Quercus arizonica and Q. grisea are amply distinct elsewhere, including large areas in northern Mexico, and they appear to be more closely related to other species than to one another (e.g., Q. arizonica with Q. oblongifolia and Q. laeta Liebmann, and Q. grisea with Q. mohriana and Q. microphylla Née). Thus, Q. arizonica and Q. grisea are best treated as distinct species that hybridize, and not as conspecific populations.

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

Quercus stellata is often identified by its commonly cross-shaped leaf form, particularly in the eastern part of its range. All individuals and populations do not express this characteristic, however. Moreover, Q. stellata has broad overlap with Q. margaretta and even with some forms of the blackjack oak, Q. marilandica, one of its most common associates. The thick yellowish twigs with indument of stellate hairs and the dense harsh stellate hairs on the abaxial leaf surface are better diagnostic characteristics when variation includes leaf forms that are not obviously cruciform.

Native Americans used Quercus stellata medicinally for indigestion, chronic dysentery, mouth sores, chapped skin, hoarseness, and milky urine, as an antiseptic, and as a wash for fever and chills (D. E. Moerman 1986).

Putative hybrids are known with Quercus marilandica, Q. alba, and various other white oaks. Quercus stellata is also one of the few oaks that appears to produce hybrids with species in the live oak group, although obvious intermediates are rarely encountered. Nothospecies names based on putative hybrids involving Q. stellata include: Q. ×stelloides E. J. Palmer (= Q. prinoides × Q. stellata), Q. ×mahloni E. J. Palmer (as Q. sinuata var. breviloba × Q. stellata), Q. ×pseudomargaretta Trelease (= Q. margaretta × Q. stellata), Q. ×sterretti Trelease (= Q. lyrata × Q. stellata), Q. ×macnabiana Sudworth (= Q. sinuata × Q. stellata), Q. ×guadalupensis Sargent (= Q. sinuata × Q. stellata), Q. ×fernowi Trelease (= Q. alba × Q. stellata), and Q. ×bernardensis W. Wolf (= Q. montana × Q. stellata).

(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. 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. 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. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Synonyms Q. sacame Q. minor, Q. obtusiloba
Name authority Sargent: Gard. & Forest 8: 92. (1895) Wangenheim: Beytr. Teut. Forstwiss., 78, plate 6, fig. 15. (1787)
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).



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