Drought Tolerance of Selected Non-Irrigated Trees

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SeÃn O.
http://about.me/seanaohara


The following is a list of trees from Landscape and Irrigation magazine (Aug 1986), entitled 'Drought Tolerance of Selected Non-Irrigated Trees' (by Donald R. Hodel). This work is based upon a study of an area in Los Angeles where all the residences were demolished in 1978 for the construction of the Century Freeway. Apparently, only the trees remained from the demolition, and they remained untended, un-irrigated, for a period of 8 years. All specimens were mature, and presumably had received 'normal' care during the first part of their life (I suspect they received widely varying degrees of appropriate care, as is common in neighborhoods!). The trees I've listed below were given the highest ratings, meaning they looked relatively unaffected by the period of neglect. It is an interesting article, and worth looking up.
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Note that these are trees that HAPPENED to be in the study due to their existence on this property - it does by no means exclude other trees that might be just as tolerant of drought and neglect. BTW, some trees traditionally thought of as the toughest, did not fair as well as these (e.g. Ficus carica (common Fig), Fraxinus velutina (Arizona Ash), Ginko biloba (Maindenhair Tree), Populus fremontii (Rio Grande Cottonwood), Prunus caroliniana (Carolina Cherry), Robinia pseudoacacia (Pink Locust) and Tristania conferta (Brisbane Box) were all dead or experienced severe die-back.
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ÂH O R T U L U SÂÂ A P T U SÂ ('gardens', 'suited to their purpose')
ÂSean A. O'Hara
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botanical nameÂÂÂÂÂÂÂÂÂÂÂÂ common name - Sunset Western Garden Zones
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Araucaria bidwilliiÂÂÂÂÂÂÂ Bunya-bunya - 7-9, 12-24
Brachychiton populneusÂÂÂÂ Bottletree - 12-24
Brahea edulisÂÂÂÂÂÂÂÂÂÂÂÂÂ Guadaloupe Palm - 13-24
Carya illinoiensisÂÂÂÂÂÂÂÂ Pecan - 7-9, 12-16, 18-23
Cedrus deodaraÂÂÂÂÂÂÂÂÂÂÂÂ Deodar Cedar, Indian Cedar - 4-12, 14-24
Ceratonia siliquaÂÂÂÂÂÂÂÂÂ Carob Tree, St. John's Bread - 9, 13-16, 18-24
Chorisia speciosaÂÂÂÂÂÂÂÂÂ Floss Silk Tree - 15-24
Cinnamomum camphoraÂÂÂÂÂÂÂ Nepal Camphor Tree - 8-9, 12-24
Citrus xparadisiÂÂÂÂÂÂÂÂÂÂ Grapefruit - 8-9, 12-24
Cupaniopsis anacardioides Carrot Wood, Tuckeroo - 16-17, 19-24
Cupressus glabraÂÂÂÂÂÂÂÂÂÂ Smooth Arizona Cypress - 5, 8-24
Cupressus sempervirensÂÂÂÂ Italian Cypress - 4-24 (best in 8-15, 18-20)
Eriobotrya deflexaÂÂÂÂÂÂÂÂ Bronze Loquat - 8-24
Eucalyptus cinereaÂÂÂÂÂÂÂÂ Silver Dollar Gum, Argyle Apple - 8-24
Eucalyptus ficifoliaÂÂÂÂÂÂ Red Flowered Gum - 8-24
Eucalyptus globulusÂÂÂÂÂÂÂ Blue Gum - 8-24
Eucalyptus polyanthemosÂÂÂ Silver Dollar Gum, Red Box G. - 8-24
Ficus microcarpa nitidaÂÂÂ Indian Laurel Fig - 9, 15-24
Ficus rubiginosaÂÂÂÂÂÂÂÂÂÂ Rusty Leaf Fig - 18-24
Grevillea robustaÂÂÂÂÂÂÂÂÂ Silk Oak - 8-9, 12-24
Jacaranda ovalifoliaÂÂÂÂÂÂ Jacaranda - 15-24
Juniperus chinensisÂÂÂÂÂÂÂ Chinese Juniper - 1-24
Koelreuteria bipinnataÂÂÂÂ Chinese Flame or Goldenrain Tree - 8-24
Ligustrum lucidumÂÂÂÂÂÂÂÂÂ Glossy or Chinese Privet - 5-6, 8-24
Morus albaÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ White Mulberry - 1-24
Olea europaeaÂÂÂÂÂÂÂÂÂÂÂÂÂ European Olive - 8-9, 11-24
Persea americanaÂÂÂÂÂÂÂÂÂÂ Avacado - 9, 16-24
Phoenix canariensisÂÂÂÂÂÂÂ Canary Island Palm - 9, 12-24
Pinus canariensisÂÂÂÂÂÂÂÂÂ Canary Island Pine - 10-20oF
Pinus halepensisÂÂÂÂÂÂÂÂÂÂ Aleppo Pine, Jerusalem Pine - to 0oF (mature)
Pinus pineaÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ Italian Stone Pine, Umbrella Pine
Pinus radiataÂÂÂÂÂÂÂÂÂÂÂÂÂ Monterey Pine - to 15oF
Pittosporum rhombifoliumÂÂ Queensland Pittosporum - 12-24
Platanus racemosaÂÂÂÂÂÂÂÂÂ California Sycamore - 4-24
Podocarpus graciliorÂÂÂÂÂÂ African Fern Pine - (8,9,12 - warmest) 13-24
Quercus lobataÂÂÂÂÂÂÂÂÂÂÂÂ Valley Oak - 1-3, 6-16, 18-21
Schinus terebinthifoliusÂÂ Brazilian Pepper Tree - 15-17, 19-24
Washingtonia filiferaÂÂÂÂÂ Calfornia Fan Palm - 8-9, 11-24
Washingtonia robustaÂÂÂÂÂÂ Mexican Fan Palm, Skyduster - 8-9, 11-24
Yucca aloifoliaÂÂÂÂÂÂÂÂÂÂÂ Spanish Bayonet - 7-24