Quercus × macdonaldii

Quercus × macdonaldii,[1][3][4] formerly Quercus macdonaldii, with the common names MacDonald's oak and Macdonald oak, is a rare hybrid species of oak in the family Fagaceae.[1]

Quercus × macdonaldii
Leaves from an individual on Santa Cruz Island, California
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Fagaceae
Genus: Quercus
Subgenus: Quercus subg. Quercus
Section: Quercus sect. Quercus
Species:
Q. × macdonaldii
Binomial name
Quercus × macdonaldii
Greene & Kellogg (pro sp.)[1]
Synonyms[2]
  • Quercus dumosa var. macdonaldii (Greene & Kellogg) Jeps.
  • Quercus dumosa subsp. macdonaldii (Greene & Kellogg) A.Camus
Distribution map for Quercus × macdonaldii,
on the California Channel Islands

Description

The tree is between 5 to 15 meters tall, with scaly bark on the trunk. The twigs are gray and tomentose. The leaves are between 4 to 7 centimeters in length, the blades are oblong to obovate, and adaxially glabrous to sparsely hairy. The petioles are between 3 to 10 millimeters. The fruits cup is between 10 to 20 millimeters long and 6 to 10 millimeters deep. The nuts are between 20 to 35 millimeters long and conic-oblong or ovoid. The flowering time is between the months of March to May.[5]

Distribution

The tree is endemic to the California Channel Islands, on Santa Cruz Island, Santa Rosa Island, and Santa Catalina Island, in Southern California.[3] It is found in chaparral and woodlands habitats in canyons and slopes below 600 metres (2,000 ft).[3]

Taxonomy

The plant was reclassified as Quercus × macdonaldii, a naturally occurring hybrid of Quercus lobata and Quercus pacifica, or possibly other oak species.[3][4][6] Both parents are placed in section Quercus.[7] It is considered a species by Greene but derived from hybrids involving Quercus pacifica, Quercus lobata, and possibly others.[5]

See also
  • Natural history of the Channel Islands of California

References
  1. ITIS Standard Report Page: Quercus X macdonaldii. Retrieved 28 February 2015.
  2. "Quercus × macdonaldii Greene & Kellogg". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2023-02-19.
  3. Jepson: Quercus × macdonaldii. Retrieved 28 February 2015.
  4. USDA: Quercus × macdonaldii. Retrieved 28 February 2015.
  5. "Quercus ×macdonaldii". ucjeps.berkeley.edu. Retrieved 2023-10-10.
  6. Kevin, Nixon (2002). "The oak (Quercus) biodiversity of California and adjacent regions" (PDF). Proceedings of the Fifth Symposium on Oak Woodlands: Oaks in California's Challenging Landscape.
  7. Denk, Thomas; Grimm, Guido W.; Manos, Paul S.; Deng, Min & Hipp, Andrew L. (2017). "Appendix 2.1: An updated infrageneric classification of the oaks" (xls). figshare. Retrieved 2023-02-18.
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