Juglans californica

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 Juglans californica subsp. var.  
California Black Walnut
Habit: tree
Height: to
Width: to
30ft 30ft
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Width: warning.png"" cannot be used as a page name in this wiki. to 30 ft
Lifespan: perennial
Exposure: sun
Features: edible
Hidden fields, interally pass variables to right place
Minimum Temp: °Fwarning.png"°F" is not a number.
USDA Zones: 7 to 10
Sunset Zones:
Flower features:
Juglandaceae > Juglans californica var. , S. Wats.

Juglans californica, the California Black Walnut, also called the California Walnut, or the Southern California Black Walnut, is a large shrub or small tree (up to 30 feet tall) endemic to California. Some authorities (e.g. the California Native Plant Society) combines this species with J. hindsii. On the other hand, a 2007 molecular analysis of the genus[1] suggests that J. californica is sister to the remaining black walnuts (Rhysocaryon).This article uses the The Jepson Manual convention of species, [2][3].

Juglans californica, generally found in the southern half of the state, can be either a large shrub with 1-5 trunks, or a small single-trunked tree. The main trunk can fork close to the ground making it look like two trees that have grown together, then diverged. It has thick bark, deeply channeled or furrowed at maturity. It has large, pinnately compound leaves with 11-19 lanceolate leaflets with toothed margins and no hair in the vein angles[4]. It has a small hard nut in a shallowly grooved thick shell that is difficult to remove.

The Chumash Indians of the Channel Islands of California and Ventura County eat the nuts, however, they are not grown commercially for this purpose.

J. californica is threatened by development and overgrazing. Some native stands remain in urban Los Angeles in the Santa Monica Mountains and Hollywood Hills. J. californica grows in riparian woodlands, either in single species stands or mixed with California's oaks (Quercus) and cottonwoods (Populus).

J. californica grows as part of mixed woodlands in California's Coast Ranges, Transverse Ranges, and Peninsular Ranges, and also on slopes and in valleys wherever conditions are favorable throughout California west of the Sierra Nevada and the deserts and south of the Klamath Mountains. J. californica is cultivated as an ornamental tree wherever it will grow in California, and in Hawaii.

Standard Cyclopedia of Horticulture

Juglans californica, walt. shrub or tree, 12-20, rarely 40-50 ft. high: branchlets puberulous: petioles glandular-pubescent; lfts. 11-15, rarely to 19, oblong-lanceolate, usually acute, or acuminate, cuneate or rounded at the base, glabrous, 1-2 1-2½in. long: stamens 30-40: fr. globose, 1/3 -3/4 in. across, puberulous, husk thin: nut nearly globose with deep longitudinal grooves. S. Calif.

The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.



Pests and diseases




  1. Aradhya, M. K, D. Potter, F. Gao, & C. J. Simon: "Molecular phylogeny of Juglans (Juglandaceae): a biogeographic perspective: Tree Genetics & Genomes (2007)3:363-378
  2. http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?76333
  3. http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?Juglans+hindsii&expand=1
  4. Kershner, Mathews, Nelson, and Spellenberg, National Wildlife Federation field Guide to Trees of North America, 2008, Chanticleer Press, Inc. p. 229

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