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bluejack oak

Mexican blue oak, Sonoran blue oak

Habit Trees, deciduous, to 10 m. Bark dark brown to black with square plates. Trees, evergreen, to 10 m. Bark gray or whitish, closely furrowed.
Twigs

brown to reddish brown, 1-2.5 mm diam., tomentose to sparsely pubescent.

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

Buds

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

stipules persistent about terminal buds.

Leaves

blade narrowly ovate or elliptic to obovate, usually widest near middle, planar, 30-100 × 12-35 mm, base acute (rarely attenuate) to rounded, margins entire, with 1 apical awn (leaves on juvenile or 2d-flush growth may have 2-3 shallow lobes and 3-5 awns), apex acute or obtuse, rarely rounded;

surfaces abaxially densely tomentose, hairs in vein axils often reddish, easily distinguished from others, adaxially often glossy, sparsely pubescent, especially along midrib and near base, veins often raised.

blade oblong to elliptic, occasionally lanceolate or ovate, (20-)30-60(-80) × (5-)10-25(-30) 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 densely and loosely glandular-tomentose, quickly glabrate or persistently floccose, especially about base of midrib, at maturity strongly glaucous, adaxially dull pale green, bluish green, or glaucous, sparsely stellate-tomentose, quickly glabrate.

Acorns

biennial;

cup saucer-shaped to bowl-shaped, 4.5-8 mm high × 10-18 mm wide, covering 1/4-1/3(-1/2) nut, outer surface pubescent or puberulent, inner surface uniformly pubescent, scale tips tightly appressed, obtuse or acute;

nut ovoid (rarely subglobose) to broadly ellipsoid, 10-17 × 10-16 mm, occasionally striate, glabrate, scar diam. 5.5-10.5 mm.

solitary or paired, subsessile or on peduncle 4-12 mm;

cup cup-shaped, about 6-8(-13) mm deep × 10-13 mm wide, enclosing ca. 1/3 nut, scales to 1-1.5 mm wide, moderately, regularly tuberculate near base of cup, gray-pubescent;

nut light brown, ovoid or oblong, 12-17(-19) × (7-)10-12 mm, glabrate or puberulent about apex.

Cotyledons

connate.

Terminal

buds light brown to reddish brown, narrowly ovoid to conic, 3.5-7 mm, distinctly 5-angled in cross section, scales pubescent, often tuft of reddish or silvery hairs at apex.

Quercus incana

Quercus oblongifolia

Phenology Flowering spring. Flowering in spring.
Habitat Well-drained sandy soils of barrens, hammocks, dunes, and upland ridges Common in high grasslands and midelevation woodlands, mesas, and canyons
Elevation 0-250 m (0-800 ft) 1300-1650 m (4300-5400 ft)
Distribution
from FNA
AL; AR; FL; GA; LA; MS; NC; OK; SC; TX; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico (Baja California South, Sonora, Chihuahua, and Coahuila)
[WildflowerSearch map]
[BONAP county map]
Discussion

Quercus incana reportedly hybridizes with Q. falcata [= Q. ×subintegra (Engelmann) Trelease], Q. hemisphaerica (D. M. Hunt 1989), Q. laurifolia (= Q. ×atlantica Ashe), Q. laevis (= Q. ×asheana Little), Q. marilandica (= Q. ×cravenensis Little), Q. nigra (= Q. ×caduca Trelease), and Q. phellos (E. J. Palmer 1948); with Q. pumila (D. M. Hunt 1989); and with Q. velutina (= Q. ×podophylla Trelease), and questionably, Q. myrtifolia.

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

Source FNA vol. 3. FNA vol. 3.
Parent taxa Fagaceae > Quercus > sect. Lobatae 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. 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. 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. cinerea
Name authority W. Bartram: Travels Carolina, 378. (1791) Torrey: in L. Sitgreaves, Rep. Exped. Zuni Colorado Rivers, 173, plate 19. (1853)
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