Herb: Californian Black Oak

Latin name: Quercus kelloggii

Synonyms: Quercus californica, Quercus sonomensis, Quercus tinctoria californica

Family: Fagaceae (Beech Family)

Medicinal use of Californian Black Oak:

Any galls produced on the tree are strongly astringent and can be used in the treatment of haemorrhages, chronic diarrhoea, dysentery etc.

Description of the plant:


25 m
(82 feet)


Habitat of the herb:

Clay or gravelly soils in hills and mountains below 2500 metres. Sometimes forms groves of considerable extent in coniferous forests.

Edible parts of Californian Black Oak:

Seed - cooked.Used as a staple food by several native North American Indian tribes. A bitter taste. The seed is 25 - 30mm long and 18mm wide, it can be dried, ground into a powder and used as a thickening in stews etc or mixed with cereals for making bread. The seed contains bitter tannins, these can be leached out by thoroughly washing the seed in running water though many minerals will also be lost. Either the whole seed can be used or the seed can be dried and ground it into a powder. It can take several days or even weeks to properly leach whole seeds, one method was to wrap them in a cloth bag and place them in a stream. Leaching the powder is quicker. A simple taste test can tell when the tannin has been leached. The traditional method of preparing the seed was to bury it in boggy ground overwinter. The germinating seed was dug up in the spring when it would have lost most of its astringency. The roasted seed is a coffee substitute.

Other uses of the herb:

A mulch of the leaves repels slugs, grubs etc, though fresh leaves should not be used as these can inhibit plant growth. Oak galls are excrescences that are sometimes produced in great numbers on the tree and are caused by the activity of the larvae of different insects. The insects live inside these galls, obtaining their nutrient therein. When the insect pupates and leaves, the gall can be used as a rich source of tannin, that can also be used as a dyestuff. The galls have been used as a dark dye for the hair. Acorn meal has been used to mend cracks in clay pots. Wood - coarse-grained, heavy, hard, strong, very brittle, not very durable. It is of little economic importance, but is occasionally used for fence posts and as a fuel.

Propagation of Californian Black Oak:

Seed - it quickly loses viability if it is allowed to dry out. It can be stored moist and cool overwinter but is best sown as soon as it is ripe in an outdoor seed bed, though it must be protected from mice, squirrels etc. Small quantities of seed can be sown in deep pots in a cold frame. Plants produce a deep taproot and need to be planted out into their permanent positions as soon as possible, in fact seed sown in situ will produce the best trees. Trees should not be left in a nursery bed for more than 2 growing seasons without being moved or they will transplant very badly.

Cultivation of the herb:

Clay or gravelly soils in hills and mountains below 2500 metres. Sometimes forms groves of considerable extent in coniferous forests.

Known hazards of Quercus kelloggii:

None known

Plant information taken from the Plants For A Future.