Juglans hindsii aka Hinds's Black Walnut

Juglans hindsii, or northern California walnut, is a deciduous tree. It belongs to the walnut family, Juglandaceae. Its native range lies in north-central California. It grows near the coast and beside rivers and streams. It also occurs on some slopes of the Napa Range. Wild sites include rocky or gravelly soils with good drainage.

This tree grows at a moderate rate. Garden height reaches about 49 feet [15 metres]. Another account gives heights up to 60 feet [18.3 metres]. It usually forms one straight trunk with a broad crown. Gray or brown bark has shallow cracks and flat, scaly ridges. Stout young twigs turn from green to reddish brown. Their pith has chambers, and large leaf scars have three lobes. The alternate, pinnate leaves carry 15 to 19 narrow leaflets. Each leaflet has fine teeth along its edge. The upper face shines green; the lower face is paler.

Flowers appear with the new leaves in spring. Plants For A Future gives flowering as May to June. Each tree bears separate male and female flowers. Yellow-green male catkins hang from the previous year's twigs. Tiny female flowers sit near the tips of new shoots. They grow alone or in groups of two or three. Wind carries the pollen, and the species is self-fertile. Round fruits ripen in fall, changing from green to brown. The nut beneath the husk has a nearly smooth shell.

Grow this walnut in full sun, away from strong winds. It prefers deep, well-drained loam and moist soil. It accepts sand and clay when drainage is good. Mildly acid through mildly alkaline soils suit it. A deep taproot gives some drought tolerance. That root also makes the tree sensitive to root disturbance. Plant seedlings in their final site while still young. Give them winter shelter during their first year or two. Plants For A Future lists USDA zones 8–9. It reports survival at Kew, but poor results in colder areas.

The tree serves as a specimen or woodland canopy tree. Growers also use it as rootstock for English walnut. Its small, sweet seeds are edible raw but have thick shells. Seed oil is edible, though it spoils quickly. The husks yield a black dye. Rain can wash growth-suppressing chemicals from leaves into the soil. This can limit plants growing beneath the crown. Plants For A Future reports no known hazards or medicinal uses.