Common Name: Desert Fan Palm

General Information

Washingtonia filifera is an evergreen palm tree producing a single, unbranched stem that can be 100 - 150cm in diameter. The stem is topped by a crown of fan-shaped leaves 100 - 200cm wide on petioles 100 - 200cm long; the tree can grow up to 20 metres tall[].
The tree is harvested from the wild for local use as a food and source of materials. It is commonly grown as an ornamental in gardens.
The plant is classified as 'Near Threatened' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

None known

Botanical References

Range

South-western N. America - southern California, western Arizona, northwest Mexico (Baja California).

Habitat

Often forming pure stands, growing in extensive groves or small isolated clumps in moist alkaline spots in rocky canyons about seeps, springs and streams; at elevations below 1,500 metres[, , , ].

Properties

Conservation Status	Near Threatened
Edibility Rating
Other Uses Rating
Habit	Evergreen Tree
Height	12.00 m
Growth Rate	Medium
Cultivation Status	Ornamental, Wild

Cultivation Details

Washingtonia filifera is a plant of semi-arid climates with hot, mainly dry summers and cool to cold moist winters. It can tolerate light frosts and should succeed outdoors in the mildest parts of the temperate zone[, ]. Plants have been known to tolerate short-lived lows down to about -17°c so long as the climate is dry[, ]. Average annual precipitation can range from 80 - 200mm[].
Requires a sheltered sunny position in a fertile moist but well-drained soil[, ]. Plants are often found in soil with a high pH, often around 9.2 or higher[]. Tolerates some salt in the soil[] and maritime exposure in climates that are warmer than Britain[]. Plants can tolerate extensive droughts so long as their roots have tapped into underground water supplies[].
This species has an extensive and fleshy but strong root system that can penetrate to a considerable depth in search of water[]. It generally establishes best when planted out at a young stage. However, older plants are substantially more cold tolerant than juvenile plants[]. In areas at the limit of their cold tolerance, therefore, it is prudent to grow the plants in containers for some years, giving them winter protection, and only planting them into their permanent positions when sheer size dictates[]. Palms can also be transplanted even when very large. Although the thick fleshy roots are easily damaged and/or desiccated, new roots are generally freely produced. It is important to stake the plant very firmly to prevent rock, and also to give it plenty of water until re-established - removing many of the leaves can also help[].
Plants produce a 'skirt' of old dead leaves, this can be a fire hazard and the old leaves are usually removed when being grown in areas liable to forest fires[].
The trees are fire resistant. They are rarely killed by either the inital burning of their shag or by subsequent burnings. Burning experiments show that their fibrous trunks are difficult to ignite and almost impossible to flame[]..
A fast growing tree, even when young, in its native environment and very tolerant of transplanting despite its deep root system[].

Edible Uses

Fruit - raw or cooked or dried for later use[, , , , ]. It can be made into jellies and drinks or dried and ground into a meal[, ]. The seed can be ground up with the dried fruit and then both are eaten as a porridge[]. The fruit is small and hard[], but has a thin sweet pulp that tastes somewhat like dates[, ]. The ovoid fruit is about 6mm long and 4mm wide[].

Young central bud - roasted[, , ]. Harvesting this central bud will kill the tree since it is unable to make side branches[].

Young leaf bases - raw or cooked[, ].

Seed - cooked. It can be ground into a powder and used for making bread or porridge[, ].

Medicinal

None known

Agroforestry Uses:

The plant serves as an indicator species, denoting sources of year-round surface water in the desert; it is found near
seeps, springs, and streams. It also occurs in canyons where water is channeled from nearby mountains, in alluvial fan edges wheregroundwater is trapped by bedrock, and where water percolates through rock fractures caused by earthquake faulting[, ].

Other Uses

A fibre from the leaves is used in basket making and for cordage[, ]. It has been used to make clothes and sandals[, ].

The whole leaves are woven and used as the side walls and roofs of huts and temporary dwellings[, ]. The leaves can be used for matting, as a stuffing material and for rough ropemaking[].

The seeds have been used as the rattle in gourd rattles[].

The fruit stalks have been used as fire drills[].

Wood - light and soft[]. It has been used for making cooking implements, spoons etc[]. The leaf petioles are used for making spoons and hunting bows etc[].
The wood is used as kindling[].

Propagation

Seed - best sown as soon as it is ripe in a greenhouse. Pre-soaking for 24 hours in warm water may speed up germination, especially of stored seed[]. Germination can take 4 - 15 weeks to germinate. Seeds that have passed through an animal's digestive tract usually germinate faster and more easily[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first two winters. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Give the plants some protection from the cold for at least their first two winters outdoors.