Forest 21 - Mesa Oak


Quercus engelmannii

Mesa oak leaves and acorns. Photo not from the Arboretum (2)

Other common names

Engelmann oak

Origin of the species name

Quercus is Latin for oak tree; engelmannii is named after the German botanist George Engelmann (1809-1884), known for his work describing the plants of western North America in the mid 19th Century.

Family

Fagaceae

Date planted

July 2007

Lifespan

Mesa oaks live for around 350 years.

Mesa oak tree. Photo not from Arboretum

General description

This is a medium-sized tree, evergreen or drought deciduous, with a compact rounded crown. Its leaf margins are distinctive among oaks because in some populations they are entire, that is, without lobes or serrations. A third to half of the stubby brown acorn is covered with a knobbly cup. It belongs to the 'white oak' section of the genus. Height 10m Spread 10m.

Natural distribution and habitat

The species is native to southern California and north west Mexico. It is the most northerly of the sub-tropical (white) oaks and occurs in savannahs and woodlands on low hills above the dry coastal plain, usually below 1350 metres.

Conservation status

It is classified as an endangered species and is possibly the most imperilled of all tree oaks. It grows in one of the most endangered natural plant communities in California, those affected by urbanisation, as they grow in areas that have been suitable for housing development.

Uses

The acorns a valuable food for wildlife and the Acorn Woodpecker makes tree holes to store them over winter. The wood is close-grained, very heavy, hard, and strong but splits when dried, so is only used for fuel. A mulch of the leaves has been found to repel pests like slugs, and the fresh leaves inhibit plant growth. Native Americans stored the acorns for up to one year and then leached, ground and cooked into mush, soup, cakes or bread, but it is thought to have been mainly used when better foods were in short supply. The seed contains bitter tannins which is the reason for the leaching.

Planting pattern

A regular diamond grid pattern.

Further reading

Palmer, C (2008) Trees and Forests of North America. Abrams.