| Juglans californica | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Juglandaceae |
| Genus: | Juglans |
| Section: | Juglanssect. Rhysocaryon |
| Species: | J. californica |
| Binomial name | |
| Juglans californica | |
 | |
| Natural range | |
Juglans californica, theCalifornia black walnut, also called theCalifornia walnut, or theSouthern California black walnut,[1] is a large shrub or small tree (about 20–49 feet (6.1–14.9 m)[3]) of the walnut family,Juglandaceae,endemic to the Central Valley and the Coast Range valleys from Northern to Southern California.
Juglans californica is generally found in the valleys and adjacent slopes of theCalifornia Coast Ranges,Transverse Ranges, andPeninsular Ranges. It grows as part of mixed woodlands, and also on slopes and in valleys wherever conditions are favorable. It is threatened by development andovergrazing.[1] Some native stands remain in urbanLos Angeles in theSanta Monica Mountains,Hollywood Hills, and Repetto Hills.J. californica grows inriparian woodlands, either in single species stands or mixed withCalifornia's oaks (Quercus spp.) and cottonwoods (Populus fremontii). Climate model predictions indicate that *Juglans californica* may expand its range northward in response to warmer and drier conditions, potentially occupying areas currently inhabited by the endangered *Juglans hindsii* (Northern California black walnut).[4]
Juglans californica 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 11–19lanceolate leaflets with toothed margins and no hair in the vein angles.[5] It has a small hard nut in a shallowly grooved, thick shell that is difficult to remove. The tallestJuglans californica trees can reach up to 11 meters in height, though only about 10% of the population exceeds 5 meters.[6]
The nuts are edible[7] and are eaten by theChumash people of theChannel Islands of California andVentura County as well as by the Tongva of Los Angeles County.[citation needed] They are not grown commercially as food.[citation needed]
Juglans californica is cultivated throughout California to support the walnut industry, used as a rootstock in English walnut orchards. It is also cultivated as an ornamental tree where it is planted inCalifornia native plant,xeriscape, andwildlife habitat gardens andnatural landscaping in California, and in Hawaii.
Some authorities (e.g. theCalifornia Native Plant Society) combine this species withJuglans hindsii. On the other hand, a 2007 molecular analysis of the genus[8] suggestsJ. californica is sister to the remaining black walnuts (section Rhysocaryon). This article follows the conventions ofThe Jepson Manual.[9][10]
