Washingtonia is a monotypic genus of monoecious palms, native to the southwestern United States (in Arizona, California, and Nevada) and northwest Mexico (in Baja California, Baja California Sur, and Sonora). Commonly known as the desert fan palm, the genus was named in honor of George Washington, the first U.S. President, by the German botanist Hermann Wendland in 1879. The genus is among the most recognizable and widely cultivated palms worldwide.

Description

They are fan palms (subfamily Coryphoideae), with petioles armed with sharp thorns terminating in a rounded fan of numerous leaflets. The flowers are in a dense inflorescence, with the fruits maturing into a small blackish-brown drupe 6–10 mm in diameter with a thin layer of sweet flesh over the single seed.

Taxonomy

There is one accepted species in the Genus Washingtonia: Washingtonia filifera. Phylogenetic testing conducted on populations of Washingtonia palms across their native range showed four distinct genetic populations. Existing morphological distinctions between the previously accepted species did not match the distinct populations.

Washingtonia was previously divided into two species: Washingtonia filifera and Washingtonia robusta. The morphological differences between these two former species also graded into each other, and specimens with combined attributes were named Washingtonia × filibusta, assumed to be a hybrid between the two.

W. filifera includes three infraspecific varieties at this time:

  • Washingtonia filifera var. filifera
  • Washingtonia filifera var. robusta (H.Wendl.) Parish
  • Washingtonia filifera var. sonorae (S.Watson) M.E.Jones W. f. var. sonorae is native to the central coast of Sonora state, near the city of Guaymas.

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File:Washingtonia filifera — Mary's Grove — Florian Boyd 001.jpg|Washingtonia filifera var. filifera

File:Dead Sea - Kempinski Hotel (7).JPG|Washingtonia filifera var. robusta

File:Washingtonia palm2.jpg|Washingtonia palms near Twentynine Palms, California, USA

File:New_Borg_El_Arab_City_17.jpg|Washingtonia palms in New Borg El Arab, Egypt.

File:Starr 070302-4914 Washingtonia sp..jpg|Washingtonia fronds

File:Palm_tree_expo_park_coliseum_peristyle.jpg|Historic fan palm (first known transplanting late 1850s) in Exposition Park, Los Angeles, California, USA

File:華盛頓椰子 Washingtonia filifera 20220815193754 03.jpg|Washingtonia, inflorescence and the fruiting season

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References

  • Flickr: Washingtonias in Russian National Subtropical Garden
  • Flora of North America: Washingtonia
  • Scanpalm: Washingtonia
  • Washingtonia filifera: Native habitats in Arizona - reprinted from Principes, 34,(4), 1990, pp. 177-180