Flora of North America species comparison

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Quercus rubra

Quercus douglasii

chêne rouge, northern red oak, red oak

blue oak
Habit Trees, deciduous, to 30 m. Bark gray or dark gray, ridges wide, shiny, separated by shallow fissures, inner bark pinkish. Trees, deciduous, with single trunks, sometimes with few to several trunks.
Bark

gray, scaly.
Twigs

reddish brown, 2-3.5(-4.5) mm diam., glabrous.

reddish or yellowish, ca. 2 mm, densely or sparsely puberulent, occasionally glabrate with age.
Buds

reddish brown, rarely yellowish, broadly ovoid to rarely subglobose, (2-)3-5 mm;

scales glabrous except for ciliate margins, sometimes sparsely or densely pubescent.
Leaves

blade ovate to elliptic or obovate, 120-200 × 60-120 mm, base broadly cuneate to almost truncate, margins with 7-11 lobes and 12-50 awns, lobes oblong, occasionally distally expanded, separated by shallow sinuses, sinuses usually extending less than 1/2 distance to midrib, apex acute;

surfaces abaxially pale green, often glaucous, glabrous except for minute axillary tufts of tomentum, adaxially dull green, glabrous, secondary veins raised on both surfaces.

blade obovate or elliptic, oblong or oblanceolate, (20-)40-60(-80) × (15-)20-30(-40) mm, base rounded-attenuate or rounded, rarely cuneate, margins shallowly lobed or irregularly toothed, sometimes entire, lobes mucronate or rounded, secondary veins 6-10 on each side, apex rounded, rarely moderately acute;

surfaces abaxially light green or blue-green, waxy, with scattered to crowded, semi-erect, (2-)4-6(-8)-rayed stellate hairs usually 0.2-0.6 mm diam. or larger, adaxially blue-green, glaucous or grayish, vestiture similar to abaxial surface.
Acorns

biennial;

cup saucer- to cup-shaped, 5-12 mm high × 18-30 mm wide, covering 1/4-1/3 nut, outer surface puberulent, inner surface light brown to red-brown, glabrous or with ring of pubescence around scar, scales less than 4 mm, often with dark margins, tips tightly appressed, obtuse;

nut ovoid to oblong, 15-30 × 10-21 mm, glabrous, scar diam. 6.5-12.5 mm.

subsessile, solitary;

cup hemispheric or cup-shaped, rarely deeper, 5-10 mm deep × 10-15 mm wide, enclosing only base of nut, scales thin and not tuberculate to strongly and irregularly tuberculate, particularly toward base of cup;

nut thin-walled, fusiform or subcylindric, 20-30 × 10-16 mm.
Cotyledons

distinct.
Terminal

buds dark reddish brown, ovoid to ellipsoid, 4-7 mm, glabrous or with tuft of reddish hairs at apex.

2n

= 24.

= 24.

Quercus rubra

Quercus douglasii
Phenology Flowering spring. Flowering late winter–spring.
Habitat Commonly on mesic slopes and well-drained uplands, occasionally on dry slopes or poorly drained uplands Oak woodlands, margins of chaparral and grasslands
Elevation 0-1800 m (0-5900 ft) 0-1200 m (0-3900 ft)
Distribution
from FNA
AL; AR; CT; DC; DE; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; VA; VT; WI; WV; NB; NS; ON; PE; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
Discussion

Trees with large nuts only one-fourth covered by flat saucer-shaped cups often are treated as Quercus rubra var. rubra; those with smaller nuts one-third covered by cup- or bowl-shaped cups are treated as Q. rubra var. borealis (F. Michaux) Farwell. While E. J. Palmer (1942) suggested that these two varieties do not, K. M. McDougal and C. R. Parks (1986) found evidence of correspondence between morphologic types and flavonoid chemotypes. This is one of the most important ornamental and timber trees in the genus.

Native Americans used Quercus rubra for a number of medical purposes, including the treatment of sores, weakness, lung problems, sore throat, dysentery, indigestion, chapped skin, chills and fevers, lost voice, asthma, cough, milky urine, hear trouble, blood diseases, and Italian itch, and as an appetizer (D. E. Moerman 1986).

Quercus rubra reportedly hybridizes with Q. coccinea (= Q. ×benderi Baenitz) and Q. ellipsoidalis (P. C. Swain 1972; R. J. Jensen et al. 1993); with Q. ilicifolia (= Q. ×fernaldii Trelease), Q. imbricaria [Q. ×runcinata (A. de Candolle) Engelmann], and Q. marilandica (E. J. Palmer 1948; D. M. Hunt 1989); with Q. nigra (D. M. Hunt 1989); and with Q. palustris (= Q. ×columnaris Laughlin), Q. phellos (= Q. ×heterophylla F. Michaux), Q. shumardii (= Q. ×riparia Laughlin), and Q. velutina (= Q. ×hawkinsii Sudworth).

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

Populations of Quercus douglasii in coastal southern California and on the Channel Islands consist of small stands or solitary individuals often associated with Q. lobata and scrub oaks. Some doubt exists as to whether some or all of those populations are natural stands or are historical introductions near Native American settlements. Along the canyons of Santa Barbara County, putative hybrids between Q. douglasii and Q. dumosa are referred to Q. ×kinselae (C. H. Muller) Nixon. In the interior Coast Ranges of California are found numerous populations that are intermediate in form between Q. douglasii and Q. john-tuckeri (= Q. turbinella var. californica). This appears to be an area of secondary contact, and the two species remain distinct in nearby populations. Because of the widespread nature of the intermediates, following Tucker's extensive studies they can be conveniently referred to as the nothospecies Q. ×alvordiana Eastwood. The plants tend to be shrubs to small trees, with somewhat more spinose leaves than Q. douglasii and fruit similar to those of the latter species.

(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. 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. 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. 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
Synonyms Q. borealis, Q. maxima Q. douglasii var. ransomii, Q. ransomii
Name authority Linnaeus: Sp. Pl. 2: 996. (1753) Hooker & Arnott: Bot. Beechey Voy. 9: 391. (1840)
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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