Juglans californica S. Watson
Southern California Walnut, California Black Walnut
Juglandaceae (Walnut Family)
Synonym(s): Juglans californica var. californica
USDA Symbol: JUCA
Southern California walnut or California black walnut is a multi-stemmed, 20-30 ft., deciduous tree or tall shrub with pinnately compound foliage becoming yellow in fall. Small to medium-sized tree, usually forked near base, with rounded crown.
First found north of Los Angeles in 1850 by the survey of the Mexican Boundary Commission, this species is now established by planting beyond its local range. It is often small and shrublike; in contrast, Northern California Walnut becomes a tall tree with larger nuts to 2" (5 cm) in diameter.
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Plant CharacteristicsDuration: Perennial
Leaf Retention: Deciduous
Leaf Complexity: Pinnate
Breeding System: Flowers Unisexual , Monoecious
Size Notes: Up to about 30 feet tall.
Bloom InformationBloom Color: White , Green , Brown
Bloom Time: Mar , Apr , May , Jun
Native Distribution: Coastal CA from Ventura Co. south, e. to the foothills of the San Bernadino Mts.
Native Habitat: Streambanks, hills & valleys below 2500 ft.
Growing ConditionsLight Requirement: Part Shade
Soil Description: Poor, mesic soils.
Conditions Comments: Juglans californica can be single-stemmed with training. Juglans hindsii, found near former Indian encampments throughout CA, is doubtfully distinct from J. californica. J. hindsii is usually single-trunked and up to 50 ft. tall. It is used as a street tree and as stock for budding English walnuts.
PropagationDescription: Plant nuts in fall or spring. If nuts are sown in spring, they must be stratified.
Seed Collection: Not Available
Seed Treatment: Stratify for 60-120 days at 34-41 degrees.
Commercially Avail: yes
National Wetland Indicator Status
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Santa Barbara Botanic Garden - Santa Barbara, CA
Web ReferenceWebref 30 - Calflora (2018) Calflora
Webref 37 - Calscape (2019) California Native Plant Society
Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Additional resourcesUSDA: Find Juglans californica in USDA Plants
FNA: Find Juglans californica in the Flora of North America (if available)
Google: Search Google for Juglans californica
MetadataRecord Modified: 2022-10-06
Research By: TWC Staff