![]() The tree is usually <30' tall, and often has multiple trunks. © Joan Avise |
California Black Walnut Juglans californica Common on hillsides in oak woodland and grassland with scattered trees in Chino Hills, Santa Ana Canyon and Santa Ana Mtns. There are trees that were planted in 1974 along SR74 which are now propagating into adjacent wilderness areas. Walnuts are monoecious, bearing separate male and female flowers on the same tree. Petals and sepals are lacking from both types of flower. Catkins (male inflorescences) are produced laterally on one-year old wood, and female flowers are produced terminally in spikes of 2-6 on current season’s wood. Walnuts are self-fertile and wind-pollinated, but self-fertilization is prevented because male flowers shed pollen before the female flowers on the same tree can receive it. Although many trees and small populations have established themselves through Orange County, probably the only naturally occuring populations are those in the Northern portions of the county. Others trees, such as along Santiago Canyon Road, Laguna Canyon Road, Silverado Canyon Road and elsewhere are probably all from cultivation. Thousand Cankers Black Walnut Disease, a fatal black fungus identified in 2008, is killing many of these trees in both eastern and western US. It is introduced just under the tree's bark by the Walnut Twig Beetle (Pityophthorous juglandis).Back to Juglandaceae of Orange County, California |
![]() Silverado Trk. Trail, Western Silv. Cyn., 11-13-11. © Ron Vanderhoff |
![]() Irvine Mesa, Silverado Trk. Trail, Western Silv. Cyn., 11-13-11. © Ron Vanderhoff |
![]() Williams Cyn., Santa Ana Mts., 5-12-12. © Ron Vanderhoff |
![]() South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
![]() Thick furrowed bark 8-11-07. © Joan Avise |
![]() South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. 4-7-13. © Ron Vanderhoff |
![]() The 8" pinnately compound leaves have 11-15 leaflets. 7-20-11. © Joan Avise |
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![]() Leaflets. © Joan Avise |
![]() Deciduous compound leaves with 11-19 leaflets 7-20-11. © Joan Avise |
![]() Hwy 74, 2.5 miles E of Hot Springs Rd., 8-23-12. © Ron Vanderhoff |
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![]() Catkins (male inflorescences) produced laterally on one-year old wood. South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. 4-7-13. © Ron Vanderhoff |
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![]() Catkins (male inflorescences) produced laterally on one-year old wood. South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. 4-7-13. © Ron Vanderhoff |
![]() Catkins (male inflorescences). South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
![]() Catkins (male inflorescences). South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
![]() Female flowers are produced terminally in spikes of 2-6 on current season’s wood. South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
![]() Female flowers are produced terminally in spikes of 2-6 on current season’s wood. South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
![]() Female flowers are produced terminally in spikes of 2-6 on current season’s wood. South end of Stagecoach Trail, Laurel Canyon, Laguna Coast Wilderness Park, Laguna Beach, Orange County, CA. © Peter J. Bryant |
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![]() Fruit. Hwy 74, 2.5 miles E of Hot Springs Rd., 8-23-12. © Ron Vanderhoff |
![]() Fruit. Hwy 74, 2.5 miles E of Hot Springs Rd., 8-23-12. © Ron Vanderhoff |
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![]() Green husk on fallen fruit 7-20-11. © Joan Avise |
![]() Same fruit aged three months 10-7-11. © Joan Avise |
![]() Cross section of thick-shelled nut 10-7-11. © Joan Avise |
![]() Fall colors. Aliso Creek, vic. Awma Rd., Laguna Niguel;, 11-16-15. © Ron Vanderhoff |
![]() Fall colors. Aliso Creek, vic. Awma Rd., Laguna Niguel;, 11-16-15. © Ron Vanderhoff |