Quercus phillyreoides aka Black Ridge Oak

Quercus phillyreoides is an evergreen shrub in the beech family, Fagaceae. Its common names include black ridge oak and Ubame oak. It comes from southern China and parts of Japan. Its range includes Yakushima and the Nansei Islands. In central and southern Japan, it grows near the coast. There it forms part of thickets and open woods.

This slow-growing oak can reach about 30 feet [9 metres]. It keeps its leaves throughout the year. Plants For A Future lists it for woodland garden canopies. It also values the species as an ornamental plant. Moderate exposure can limit its growth without killing it. Young plants can cope with some shade from the sides.

Flowers appear from April to May, and wind carries the pollen. Each plant bears separate male and female flowers. Seeds ripen from October to November. Plants For A Future says they take two years to mature. British plants seldom produce good seed crops. Yet trees at Kew cropped well during the hot summer of 1989. The seeds reach about 0.07 feet [0.02 metres] long.

Give this oak deep, fertile loam that holds moisture. It also grows in heavy clay. It accepts mildly acid, neutral, and mildly alkaline soils. Full sun and partial shade both suit it. It withstands strong winds but not direct maritime exposure. Plants For A Future lists USDA zones 6–9. Young plants form a deep taproot and dislike delayed transplanting. Plant them in their final place while still young. Seeds lose viability when dry, so sow them soon after ripening.

Cooked seeds have food uses after their bitter tannins are removed. Ground seeds can thicken stews or join cereal flour for bread. Leaching whole seeds may take days or weeks. Ground seed loses its tannins faster. Plants For A Future reports no known hazards. This does not remove the need for proper seed preparation. The source also records medicinal uses for astringent galls. Insect larvae cause these growths and live inside them. Galls provide tannin and material for dyes after the insects leave. Leaf mulch has reported uses against slugs and grubs. Avoid fresh leaves for mulch, as they can hinder plant growth.