Quercus durata aka Leather Oak

Quercus durata, or leather oak, is an evergreen California shrub. It belongs to the beech and oak family, Fagaceae. Its native range includes the Coast Ranges and Sierra Nevada foothills. It also grows around San Francisco Bay and the San Gabriel Mountains. It lives in chaparral and foothill woods. Garden references give heights of 3–10 feet [0.9–3 metres]. Plants For A Future gives a taller limit of 13 feet [4 metres]. Dense branches form a rounded crown, sometimes making broad clumps.

The bark is pale gray, with small, fine scales. Slender twigs bear hairs, which may disappear as stems age. The small, round buds are reddish brown. Leaves grow alternately and stay on the shrub year-round. They are stiff, leathery, and oval to oblong. Their edges may be smooth, rolled under, or sharply toothed. The blades often curve rather than lie flat. Fine hairs cover the dull green upper surface. The underside is paler, with soft hairs that may look golden.

Flowers appear in April and May on fresh spring growth. Each shrub carries both male and female flowers. Wind moves pollen between them. Yellow-green male flowers hang in short catkins. Tiny female flower spikes grow where leaves meet stems. Acorns develop alone or in pairs and ripen that autumn. The nuts measure about half to one inch long. Their tips may be blunt or rounded. A rough, warty cup covers part of each nut.

Grow leather oak in sun or a lightly shaded woodland edge. It prefers moist, fertile loam and also accepts clay soil. It tolerates mildly acid, neutral, and mildly alkaline conditions. Some wind exposure is suitable, but coastal salt exposure is not. Sources differ on cold tolerance. Oregon State lists USDA Zone 8; Plants For A Future lists zones 7–10. The latter reports tolerance down to about −5 to −10°C. Cool British summers can leave new wood prone to frost damage. Roots dislike disturbance, so plant young shrubs in their lasting position. Seeds lose viability when dry and need protection from rodents.

Its dense evergreen form suits woodland edges. Cooked seeds are edible after thorough soaking removes their bitter tannins. Ground seeds can thicken food or join flour in bread. Plants For A Future reports no known hazards. It also records traditional medicinal use of astringent insect galls. Empty galls supply tannin and dye. Leaf mulch may deter slugs and grubs. Fresh leaves can hinder plant growth, so avoid using them as mulch.