Large palm tree, native to the mild areas of North America; to the genus Washingtonia also belongs the robust species, very similar to the filifera, a little less resistant to cold and with greater water requirements. The washingtonia filifera or California palm develops a fairly thin stem, slightly enlarged at the base, which can reach 15-20 meters in height; the fronds are arched, with a long rigid petiole, up to 200-250 cm long, dark green in color, the foliage, at the apex of the long petiole, constitutes a large rounded fan, consisting of pointed, ribbon-like segments, which are united in the lower part, up to two thirds of their length. As with other palm trees, even in the case of washingtonias, the fronds are evergreen, and last on the plant for several months, and then dry out. One of the distinctive features of the washingtonia lies in the fact that the dried branches remain on the plant for a long time, before falling; the foliage in fact shows in the lower part a good number of completely dry, straw-colored fronds. During the summer months it produces long clusters of yellowish flowers, followed by small dark fruits, which contain the seeds.
These palms prefer well-sunny locations, even direct ones, even if they can tolerate places with a few hours of light shade a day; they do not fear the cold weather, and they can endure very intense frosts, for not too long periods. As for the wind, however, the California palm trees can be damaged by too strong and cold gusts. This in particular concerns the younger plants that will need a support or a brace to grow at their best in those areas where the wind is present regularly.
For a good resistance of the species it is very important that during the winter period it doesn't receive any watering; for this reason it is not widely used in coastal areas.