Washingtonia robusta Seeds | Mexican Fan Palm
LATIN NAME: Washingtonia robusta
COMMON NAME: Mexican Fan Palm
Plant Profile
Washingtonia robusta is the tall, thin fan palm that lines boulevards from Los Angeles to Guangzhou, and it is usually recognised by its proportions rather than by its leaves. The trunk is narrow for a palm, often no more than forty centimetres across, and it rises twenty-five metres or more with only a slight taper. Old plants carry a skirt of dead fan leaves below the crown, and in dry air that skirt can persist for decades.
The crown is made of palmate leaves a metre across, divided into segments that hang at the tips. Flower spikes push out among the leaves in summer, and the fruit that follows is a small black date with a thin, sweet flesh and a large stone. The species is native to a narrow strip of Sonora and the Baja peninsula, where it grows along seasonal watercourses that run dry for most of the year.
Science & Biotechnology
The genus holds two species that behave very differently. Washingtonia filifera, the California fan palm, has a thick trunk, a broad crown and real cold tolerance; W. robusta has a slim trunk, a smaller crown and much less frost hardiness. Where the two meet in cultivation they hybridise freely, and many street palms are neither. The reliable distinction is the trunk and the leaf-base colour, not the height.
The dead-leaf skirt is not waste. It shields the bud from sun and wind, and in the native range it burns readily, which removes competition and releases seed onto bare ground. The palm survives fire because the bud sits at the crown, insulated by the leaf bases, and regrows within a season. Seeds pass through the gut of birds and coyotes intact and germinate readily in disturbed ground.
Uses & Benefits
The fruit is edible and was gathered by the Seri and other groups in Sonora, eaten fresh or dried and ground into a coarse flour. It is sweet but thin-fleshed, and the stone is most of the weight, so it has never become a commercial crop. The young leaf bud is also edible, though cutting it kills the palm.
The plant is used in landscaping more than for anything else: motorway verges, car parks, shopping centres. The dead leaves are cut for thatch in parts of Mexico, and the trunk is used for posts and for cheap construction where the wood is available, though the timber is soft and short-lived.
Growing from Seed
Seed germinates easily and without pretreatment. Sow at 25 to 30 degrees in a free-draining mix, keep it moist but not wet, and seedlings appear in three to six weeks. The young palm is fast, and a plant started in spring can be a metre tall by autumn, which is why the species is cheap in the trade and often sold bare-root.
Plant it in full sun and do not pamper it. Once established the palm takes drought, salt wind and poor soil, and it needs no irrigation beyond the first two summers. It does not take deep shade, and it does not take hard frost: a night at minus six will burn the crown, and repeated cold will kill it. In a cold climate, grow W. filifera or a hybrid instead.
Our Take
The cheapest way to put a tall palm in a dry garden, provided you accept the size and the litter. Buy small and plant it where it can stay.
Related Reading
More species in the same orbit as Mexican Fan Palm: