Quercus havardii |
Quercus grisea |
|
---|---|---|
Havard oak, Havard's oak, Havard's shinnery oak, sand shinnery oak, sand shinoak, shinnery oak |
gray oak |
|
Habit | Shrubs, deciduous, low, forming clones 0.3-1.5 × 10 m, rhizomatous. | |
Bark | light gray, scaly-papery. |
|
Twigs | brown or grayish, 1-2.5 mm diam., glabrous or densely short grayish or yellowish tomentulose, glabrate in age. |
gray, 1-2 mm diam., sparsely or densely stellate-tomentulose or tomentose when young. |
Buds | dark red-brown, subglobose, ca. 2 mm, sparsely pubescent. |
dark red-brown, ovoid to subglobose, 1-2 mm, stellate hairs causing yellowish color, at least on outer scales; stipules persistent, 1-4, subulate, pubescent, at base of terminal buds. |
Leaves | blade green, often turning brownish with age, polymorphic, oblong or elliptic or sometimes lanceolate to oblanceolate or ovate to obovate, (30-)50-100 × (10-)20-50 mm, rather thick and hard, base rounded to cuneate, margins flat to revolute, at least some undulate, 2-3 rounded teeth on each side, secondary veins 5-8 on each side, much branched, apex broadly rounded, rarely acute; surfaces abaxially densely grayish or yellowish tomentulose or stellate-pubescent, sometimes only sparsely pubescent, secondary veins quite prominent, adaxially lustrous, very sparsely stellate-pubescent or glabrate, secondary veins very slightly if at all raised. |
blade oblong to elliptic or ovate, (15-)25-35(-80) × (7-)15-30(-40) mm, thick and leathery, base cordate or rounded, margins minutely revolute, entire or dentate with mucronate teeth, secondary veins 6-10 on each side, branched, apex acute, sometimes obtuse, rarely rounded; surfaces abaxially dull gray-green or yellowish, minutely stellate-pubescent with interlocking hairs, secondary veins very prominent, adaxially dull green, very sparsely and minutely stellate-pubescent, secondary veins slightly raised. |
Acorns | solitary or paired, subsessile or on peduncle to 10(-18) mm; cup from deeply cup-shaped to goblet-shaped, 10-12 mm deep × 15-25 mm wide, enclosing 1/3-1/2 nut, base rounded or slightly constricted, margin very thin and smooth, scales reddish brown, triangular-ovate to long-acute, proximally moderately to markedly tuberculate, pubescent, often canescent, tips loosely appressed; nut brown, ovoid, 12-25 × 14-18 mm. |
solitary or paired, subsessile or on peduncle 0-30 mm; cup from deeply goblet- to deeply cup-shaped, 4-10 mm deep × 8-15 mm wide, enclosing to 1/2 nut, scales broadly ovate to oblong, proximal scales slightly or markedly tuberculate and whitish canescent, tips closely appressed, red-brown, thin, glabrate; nut light brown, ovoid to narrowly ovoid or ellipsoid, 12-18 × 8-12 mm. |
Cotyledons | distinct. |
connate. |
Large | shrubs or moderate trees, deciduous or subevergreen, to 10 m. Bark gray, fissured. |
|
Quercus havardii |
Quercus grisea |
|
Phenology | Flowering spring. | Flowering spring. |
Habitat | Deep, shifting or stabilized sand dunes, off deep sands in putative hybrid populations | Igneous or dolomitic slopes, oak woodlands, juniper woodlands, desert chaparral |
Elevation | 500-1500 m (1600-4900 ft) | usually above 1500 m (usually above 4900 ft) |
Distribution |
NM; OK; TX
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AZ; NM; TX; Mexico (Sonora, Chihuahua, and Durango)
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Discussion | Individual clones emerging to heights of 2-3 m from thickets occur sporadically across the Texas range of Quercus havardii and express some characteristics of Q. stellata, such as more deeply lobed leaves and smaller acorns. Such putative hybrids increase in frequency in the eastern part of the range of the species. Material of Quercus havardii from the Navajo Basin of Utah and adjacent Arizona has been treated as Q. havardii var. tuckeri Welsh. Welsh followed J. M. Tucker (1970) and interpreted these intermediate populations as putative hybrids between Q. havardii and both Q. turbinella and Q. gambelii. Giving varietal rank, instead of nothospecies status, to such populations seems arbitrary, and it certainly is inconsistent with their putative hybrid origins. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Some of the specimens referred to Quercus endemica by C. H. Muller should be placed in Q. grisea. Numerous hybrids between Quercus grisea and other white oaks, including Q. gambelii, Q. mohriana, Q. arizonica, and numerous species in northern Mexico, have been reported. In the Hueco and Quitman mountains of trans-Pecos Texas, putative hybrids of Q. grisea × Q. turbinella Greene occur. (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 | ||
Synonyms | Q. undulata var. grisea | |
Name authority | Rydberg: Bull. New York Bot. Gard. 2: 213. (1901) | Liebmann: Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 171. (1854) |
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