Difference between revisions of "Quercus douglasii"

Hooker & Arnott

Bot. Beechey Voy. 9: 391. 1840.

Common names: Blue oak
EndemicSelected by author to be illustrated
Synonyms: Quercus douglasii var. ransomii (Kellogg) Beissner Quercus ransomii unknown
Treatment appears in FNA Volume 3.
FNA>Volume Importer
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|basionyms=
 
|basionyms=
 
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|name=Variety
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|name=Quercus douglasii var. ransomii
 
|authority=(Kellogg) Beissner
 
|authority=(Kellogg) Beissner
}}{{Treatment/ID/Synonym
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|name=Quercus ransomii
 
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|elevation=0-1200 m
 
|elevation=0-1200 m
 
|distribution=Calif.
 
|distribution=Calif.
|discussion=<p>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.</p>
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|discussion=<p>Populations of <i>Quercus douglasii</i> in coastal southern California and on the Channel Islands consist of small stands or solitary individuals often associated with <i>Q. lobata</i> 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 <i>Q. douglasii</i> and <i>Q. dumosa</i> 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 <i>Q. douglasii</i> and <i>Q. john-tuckeri</i> (= <i>Q. turbinella</i> <i></i>var.<i> californica</i>). 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 <i>Q. douglasii</i> and fruit similar to those of the latter species.</p>
 
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|synonyms=Quercus douglasii var. ransomii;Quercus ransomii
 
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|family=Fagaceae
 
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|publication year=1840
 
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|special status=Endemic;Selected by author to be illustrated
 
|special status=Endemic;Selected by author to be illustrated
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/9216fc802291cd3df363fd52122300479582ede7/coarse_grained_fna_xml/V3/V3_30.xml
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|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/8f726806613d60c220dc4493de13607dd3150896/coarse_grained_fna_xml/V3/V3_30.xml
 
|genus=Quercus
 
|genus=Quercus
 
|section=Quercus sect. Quercus
 
|section=Quercus sect. Quercus

Revision as of 18:16, 18 September 2019

Trees, deciduous, with single trunks, sometimes with few to several trunks. Bark gray, scaly. Twigs 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: petiole blue-green, 2-6 mm. Leaf 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 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. 2n = 24.


Phenology: Flowering late winter–spring.
Habitat: Oak woodlands, margins of chaparral and grasslands
Elevation: 0-1200 m

Discussion

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.

Selected References

None.

Lower Taxa

None.
... more about "Quercus douglasii"
Kevin C. Nixon +  and Cornelius H. Muller +
Hooker & Arnott +
Blue oak +
0-1200 m +
Oak woodlands, margins of chaparral and grasslands +
Flowering late winter–spring. +
Bot. Beechey Voy. +
Endemic +  and Selected by author to be illustrated +
Quercus douglasii var. ransomii +  and Quercus ransomii +
Quercus douglasii +
Quercus sect. Quercus +
species +