Washingtonia robusta -- Nevada

Washingtonia robusta, or the Mexican fan palm, is a species of palm tree native to semi-arid parts of northwest Mexico that is valued as an ornamental for its striking height (up to greater than 30m) and ease of growing in landscaped areas. Its unique qualities have resulted in it becoming a popular ornamental plant in many parts of the world, where it has subsequently escaped cultivation and occasionally naturalized in riparian areas and landscaping-adjacent disturbed sites. Naturalized populations can now be found in a number of countries, including the US (California, Arizona, Nevada, Hawaii), Australia, New Zealand, and likely many places elsewhere. Washingtonia filifera currently considered invasive in California, Hawaii, and Florida. This palm has the capacity to produce huge amounts (upwards of 600,000) of fleshy fruits per year, which are sweet, nutritious, and readily dispersed long distances by vertebrates, including coyotes, foxes, and birds. However, records of naturalized individuals are rarely found in a climate matching Nevada, likely due to the need for permanently wet soils. This species cannot reproduce vegetatively, and seedlings can be easily controlled by hand-pulling. This palm grows rapidly and produces copious seeds that germinate readily under the right conditions, but its need for a specific climate and environmental conditions, restricted modes of dispersal, lack of vegetative reproduction, and general lack of serious environmental impacts lead to a moderate risk PRE score of 13 for the state of Nevada.