Quercus agrifolia aka California Live Oak

Quercus agrifolia is an evergreen tree in the oak family. People call it coast live oak or California live oak. Encina is another common name. Its native range spans California and northern Baja California. It grows by the coast and streams that drain inland. It also forms groves in valleys and on wooded slopes. Some trees grow on coastal dunes. Others take shrub form in chaparral.

Garden size depends on climate and the conditions for growth. RHS gives a height of 26–39 feet [8–12 metres]. Oregon State reports 30–80 feet [9–24 metres]. Virginia Tech notes trees that reach 100 feet [30 metres]. The broad crown can spread wider than the tree's height. A short, thick trunk holds large branches. These bend and spread out. Young bark is smooth and gray-brown to nearly black. Old bark grows thick and rough, with deep grooves. Young twigs have hairs but may lose them with age.

The leaves are thick, stiff, and glossy green above. Their pale undersides have small hair tufts near vein joints. Leaves grow in an alternate pattern, taking turns along the stems. Their oval blades have rolled edges and sharp teeth. The tree sheds many old leaves in spring. Male and female flowers grow on the same tree. In spring, yellow-green male catkins hang from the tree. Small female flower spikes grow then too. The narrow brown acorns have pointed ends. Their shallow cups have scales. They ripen in early fall within their first year.

RHS calls for full sun and deep, fertile soil. The soil should drain well. Oregon State also notes growth in shade. The tree accepts sand, loam, clay, and chalk. It grows across a range of pH levels. RHS lists moist soil and UK hardiness H4. It also lists use in coastal gardens. PFAF gives USDA zones 8–11; Oregon State confirms zone 8. The broad crown suits a woodland canopy. It can also serve as a landscape feature. Growers sometimes clip it into a hedge. Aphids and caterpillars may attack it. So may leaf miners and gall wasps. RHS also lists oak processionary moth. It lists powdery mildew and honey fungus too.

PFAF notes that Indigenous North American peoples ate cooked seeds. The bitter seeds need thorough leaching to remove tannins before use. Ground seeds can thicken stews. They can also join grain flour for bread. Sources differ on safety. PFAF lists no known hazards. RHS records harm to humans. It warns that dogs face harm from eating it. PFAF also notes past medicinal uses of bark and galls. Other uses include fuel, tannin, and dye. Acorn cups also serve as buttons.