Quercus parvula

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Quercus parvula
Quercus parvula var. Parvula, leaves and flowers

Quercus parvula var. Parvula , leaves and flowers

Systematics
Class : Bedecktsamer (Magnoliopsida)
Eurosiden I
Order : Beech-like (Fagales)
Family : Beech family (Fagaceae)
Genre : Oak trees ( Quercus )
Type : Quercus parvula
Scientific name
Quercus parvula
Greene

Quercus parvula ( English Santa Cruz Island oak ) is a species of the beech family. The evergreen tree isnativeto the northern slopes of Santa Cruz Island and the California coastal mountains from Santa Barbara County north to Mendocino County . It was considered a form of Quercus wislizeni until it was spun off as a separate species by Nixon (1980). The locus typicus of Q. parvula var. Shrevei (originallydescribedas Q. shrevei by CH Muller) is the Palo Colorado Canyon in Monterey County. The IUCN classifies the species as "near threatened".

description

Q. parvula differs morphologically from its close relative Q. wislizeni in the following points:

  • The leaf blades are larger,> (2) 4 cm long instead of <4 (6) cm.
  • The leaf blades are thinner, usually <0.26 mm near the tip instead of usually> 0.26 mm.
  • The branches of the current year are pentagonal at their origin instead of more or less rounded.
  • The leaf stalks and branches of the current year are smooth to sparsely hairy instead of moderately to very hairy.
  • The tips of the acorns are blunt instead of sharp.
  • Abaxial, gold- shimmering, uniseriate trichomes on the leaf blade are absent or are only sporadic instead of being moderately dense or dense.
  • Abaxial multi-row trichomes on the central vein of the leaf blade are absent or present only sporadically instead of occasionally or frequently.
  • The secondary leaf veins are erect abaxially instead of being more or less adjacent.

Neither in Q. parvula nor in Q. wislizeni do the freshly unfolded leaves have a velvety covering of red bulbous trichomes on the upper side. This distinguishes them from Q. kelloggii and both varieties of Q. agrifolia , which produce such leaves.

ecology

Q. parvula is often found on the mainland near coastal redwoods ( Sequoia sempervirens ) and often in the vicinity of California holm oaks ( Quercus agrifolia var. Agrifolia ) and Lithocarpus densiflorus .

Q. parvula differs ecologically from Q. wislizeni as follows:

  • It occurs on islands and on the coast instead of in the foothills of the mountains.
  • It is more associated with coastal redwoods ( Sequoia sempervirens ) than with Digger pines ( Pinus sabiniana ).

Systematics

Quercus parvula belongs to the Lobatae ("red oak") section.

There are currently three varieties of Q. parvula :

  • Q. parvula var. Parvula , English Santa Cruz Island oak - Santa Cruz Island, California. An investigation suggests that Q. parvula var. Parvula is a hybrid ( Q. parvula var. Shrevei x Q. wislizeni ).
  • Q. parvula var. Shrevei , English Shreve oak, forest oak - Central and Northern California on the coast. If further investigation shows that the recently identified ones do not match the var. Parvula , this taxon could be revised to Quercus shrevei .
  • Q. parvula var. Tamalpaisensis , English Tamalpais oak - Marin County (California). It is an invalid taxon. More recent DNA studies have shown that it is a hybrid between Q. wislizeni and Q. parvula var. Shrevei .

Hybridization

Quercus parvula is theoretically capable of, with any other Californian red oak except Quercus agrifolia var. Oxyadenia ( English sharpacorn oak ), which occurs at higher elevations in the south Kalifornierns and by that of the Transverse Ranges is separated hybrids to be formed. In addition, the generally later flowering period of Q. parvula (April – May instead of February – April for Q. kelloggii , Q.wislizeni and Q. agrifolia ) limits the possibilities of genetic exchange.

Individual evidence

  1. ↑ a b Kevin Nixon: A Systematic Study of Quercus parvula Greene on Santa Cruz Island and Mainland California 1980.
  2. ↑ Quercus parvula . IUCN . Retrieved June 7, 2019.
  3. ^ A b c Duncan A. Hauser, Al Keuter, John D. McVay, Andrew L. Hipp, Paul S. Manos: The evolution and diversification of the red oaks of the California Floristic Province (Quercus section Lobatae, series Agrifoliae) . In: American Journal of Botany . 104, October 2017, pp. 1581–1595.
  4. ↑ a b c Quercus parvula . In: Jepson eFlora . Jepson Flora Project. 2015. Retrieved July 17, 2015.
  5. ↑ Quercus parvula Greene . In: GBIF Backbone Taxonomy . Retrieved June 7, 2019.
  6. ^ Edward L. Greene: Pittonia. A series of papers relating to batony and botanists , Volume 1 1887.
  7. ^ K. Nixon, CH Muller: New Names in California Oaks . In: Novon . 4, No. 4, 1994.
  8. ↑ Randall Morgan: An Annotated Checklist of the Vascular Plants of Santa Cruz County, California 2005.
  9. ^ SK Langer: A New Oak On Mount Tamalpais . In: Four Seasons . 9, No. 3, 1993, pp. 21-30.
  10. ↑ Torr., Sitgr. Rep., 172, pl. 17 (1853)
  11. ^ JG Cooper, Smithsonian Rep. 1858: 261 (1859)

Web links

Commons : Quercus parvula  - collection of images, videos and audio files