Palms For California

Pronunciation: wash-ing-TOE-nee-uh roe-BUST-uh

Common Name: Mexican Fan Palm, Feather Duster Palm

Washingtonia robusta is probably the most commonly grown palm in the US and one of the most recognizable palms in the world. Many consider these 'trash palms' and they are indeed one of the most serious weeds in many urban and rural areas. However common and easy to grow, these are one of the fastest growing of all palms, and quickly can become majestic landscape specimens. Few palms are more impressive than those over 80 feet tall, planted along avenues evenly spaced and all leaning the same direction (towards the ocean and the afternoon sun). Heads or more compact, greener and trunks thinner than the native California Fan Palm, Washingtonia filifera, which this one is often confused with. Many hybrid palms of the two growing in public landscaping, and referred to as 'filabustas'.

Appearance and Biology Habit: solitary with dense crown (under ideal conditions) of about 30 leaves Height: 100 feet Trunk: partial or complete retained dead leaf petticoat except in very old palms usually clean (in cultivation usually pruned clean or closely thatched); 16"-24" thick, grey (reddish when recently pruned); often leaning toward the west when very tall Spread: 6'-8' Leaf Description: palmate to barely costapalmate; 6'-7' long; deep green and glossy when mature; leaves stiff until maturing at which time leaflets tend to droop; cottony fibers associated with leaflets Petiole: long 5'-6' (about equal to rachis) and heavily armed with large, very sharp teeth mildly to severely hooked; leaf bases split upon trunk Reproduction: monoecious and 'rampant' Inflorescence: long, arching, dark brown Fruit: spherical dark brown; 1cm Seed: 4-5mm spherical black

Horticultural Characteristics Minimum Temp: 20F, though moderate leaf burn at 25F Drought Tolerance: very high Dry Heat Tolerance: very high Wind Tolerance: very high Salt Tolerance: good Growth Rate: very fast (fastest palm in California and one of the fastest in the world) Soil Preference: extremely tolerant of a wide range of soil types Light Requirement: full sun, though can grow well in deep shade for years Human Hazards: falling leaves in winds dangerous to both pedestrians and cars; profuse seed production makes sidewalks slippery; petiolar teeth make pruning hazardous; dead petticoats are fire hazard and hiding place for vermin Disease or Horticultural Problems: few Indoor?: performs moderately well if bright light available, but a dangerous indoor palm; used fairly frequently in large, indoor shopping malls