Quercus alba |
Quercus engelmannii |
|
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chêne blanc, eastern white oak, white oak |
Engelmann oak, Engelmann's oak |
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Habit | Trees, deciduous, to 25 m. Bark light gray, scaly. | Trees, subevergreen, to 10 m. Bark gray or whitish, closely furrowed. |
Twigs | green or reddish, becoming gray, 2-3(-4) mm diam., initially pubescent, soon glabrous. |
light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate. |
Buds | dark reddish brown, ovoid, ca. 3 mm, apex obtuse, glabrous. |
reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds. |
Leaves | blade obovate to narrowly elliptic or narrowly obovate, (79-)120-180(-230) × (40-)70-110(-165) mm, base narrowly cuneate to acute, margins moderately to deeply lobed, lobes often narrow, rounded distally, sinuses extending 1/3-7/8 distance to midrib, secondary veins arched, divergent, (3-)5-7 on each side, apex broadly rounded or ovate; surfaces abaxially light green, with numerous whitish or reddish erect hairs, these quickly shed as leaf expands, adaxially light gray-green, dull or glossy. |
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. |
Acorns | 1-3, subsessile or on peduncle to 25(-50) mm; cup hemispheric, enclosing 1/4 nut, scales closely appressed, finely grayish tomentose; nut light brown, ovoid-ellipsoid or oblong, (12-)15-21(-25) × 9-18 mm, glabrous. |
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. |
Cotyledons | distinct. |
connate. |
2n | = 24. |
= 24. |
Quercus alba |
Quercus engelmannii |
|
Phenology | Flowering in spring. | Flowering in spring. |
Habitat | Moist to fairly dry, deciduous forests usually on deeper, well-drained loams, also on thin soils on dry upland slopes, sometimes on barrens | Oak woodlands, margins of chaparral, arroyos, slopes and bajadas |
Elevation | 0-1600 m (0-5200 ft) | 50-1200 m (200-3900 ft) |
Distribution |
AL; AR; CT; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; ON; QC
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CA; Mexico (Baja California)
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Discussion | Considerable variation in depth of lobing occurs in the leaves of Quercus alba (M. J. Baranski 1975; J. W. Hardin 1975); the species is easily distinguished from others, however, by the light gray-green, glabrous mature leaves and cuneate leaf bases. In the past Quercus alba was considered to be the source of the finest and most durable oak lumber in America for furniture and shipbuilding. Now it has been replaced almost entirely in commerce by various species of eastern red oak (e.g., Q. rubra, Q. velutina, and Q. falcata) that are more common and have faster growth and greater yields. These red oaks also lack tyloses and therefore are more suited to pressure treating with preservatives, even though they are less decay-resistant without treatment. Medicinally, Quercus alba was used by Native Americans to treat diarrhea, indigestion, chronic dysentery, mouth sores, chapped skin, asthma, milky urine, rheumatism, coughs, sore throat, consumption, bleeding piles, and muscle aches, as an antiseptic, and emetic, and a wash for chills and fevers, to bring up phlegm, as a witchcraft medicine, and as a psychological aid (D. E. Moerman 1986). Numerous hybrids between Quercus alba and other species of white oak have been reported, and some have been named. J. W. Hardin (1975) reviewed the hybrids of Quercus alba. Nothospecies names based on putative hybrids involving Q. alba include: Q. ×beadlei Trelease (= Q. alba × prinus), Q. ×bebbiana Schneider (= Q. alba × macrocarpa), Q. ×bimundorum E. J. Palmer (= Q. alba × robur), Q. ×deami Trelease (= Q. alba × muhlenbergii), Q. ×faxoni Trelease (= Q. alba × prinoides), Q. ×jackiana Schneider (= Q. alba × bicolor), and Q. ×saulei Schneider (= Q. alba × montana). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | ||
Sibling taxa | ||
Name authority | Linnaeus: Sp. Pl. 2: 996. (1753) | Greene: Ill. W. Amer. Oaks 1: 33, plate 17. (1889) |
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