Quercus grisea aka Gray Oak

Quercus grisea, or gray oak, belongs to the beech family, Fagaceae. Its native range runs from Arizona to western Texas and Mexico. It grows in oak and juniper woods and desert scrub. It also grows on rocky slopes, along streams, and in dry channels. Many sites lie above 4,920 feet [1,500 metres]. Its native climate has mild winters, hot summers, and dry springs.

Gray oak can form a shrub or a small tree. Garden dimensions are about 20 feet [6 metres] tall and wide. Other accounts give heights to 33 feet [10 metres]. Rare trees reach about 66 feet [20 metres]. Dry sites can produce low shrubs with many stems. Some spread from their roots to form thickets. Larger trees have stout, bent branches and an uneven crown. The pale gray bark splits into loose plates.

The stiff, leathery leaves grow in an alternate pattern. They are oval to egg-shaped, with smooth or lightly toothed edges. Their upper sides range from gray-green to green. Fine hairs cover the dull undersides. Leaves may fall each year or persist almost year-round. Young twigs are reddish brown with fine gray hairs. Each plant bears both male and female flowers. Yellow-green male catkins hang down as the leaves emerge. Small female flower spikes sit at the leaf bases. Wind carries the pollen. Acorns mature in early fall of the same year. A scaly, finely hairy cup covers half of each nut.

Grow gray oak in full sun and well-drained soil. It accepts sand, loam, clay, and soils low in nutrients. Sources describe acid, neutral, and mildly alkaline soils as suitable. It grows in dry or moist ground and withstands drought. PFAF lists USDA zones 7–10 and dormant tolerance near −4°F [−20°C]. Hot summers help its wood mature before winter. Cool maritime summers can leave growth prone to frost damage.

People grow gray oak as an ornamental and harvest its wood. It also attracts wildlife. PFAF reports food use of acorns after tannin removal. However, its detailed entry notes limited direct evidence for this species. Tannins occur throughout the plant and can cause illness in excess. Untreated acorns should not be treated as ready-to-eat food. Seeds lose viability when allowed to dry. Young plants form deep taproots and transplant poorly when left too long. PFAF does not class this oak as weedy.