Quercus lobata, valley oak

California valley oak grows in riparian habitats where its deep tap root can access moisture all summer long. In this way this tree is analogous the river red gum in Australia. A deciduous oak with felt-covered, matte apple green, smallish leaves, it is at first an upright tree, but as it ages the twisted branches droop gracefully downwards.

In Canberra valley oak has proved excellent, reaching about 25m in 50 plus years on the tight upland clays of the city.

A great tree for hot, riparian sites across central, southern Australia, where it will grow fast and withstand seasonal flooding, it demands greater planting. This deciduous tree is cold hardy to around -15C and drought hardy to 200mm or less if tapping the water table as well, (preferring an aquifer about 10m down) and also tolerates all soil types including very heavy ones. Without subsoil moisture, rainfall of about 500mm seems adequate if grown in thinner, stoney substrates. In its home range, it has grown to over 500 years old.

European settlers observed the native people processing valley oak acorns into a mash as a staple food, while the large conical acorns were used as pig feed by colonists.

For the farmer or gardener, valley oak offers many benefits:

  • deciduous foligage forming a wide, upright-elliptic crown
  • with gnarled, drooping branches and twisted trunk, this tree has character
  • drought hardiness
  • moderately-deep shade
  • grows in all soils; tolerates clays and silty loam and seasonal waterlogging
  • acorns can be eaten by pigs
  • bark is pewter coloured, fissured and block-shaped
  • grows fast to up to 30m on riparian soils, about 20m elsewhere
  • timber can be used for fuel, but splits unless carefully seasoned

 

Tree shape

Spreading and rounded

Mature size

Large 12-20m

Growth rate

Fast

Use

Shade, carbon store, firewood, ornamental, windbeak, acorns

Soil type

All soils, good in loamy clays

Water

Drought hardy

Foliage

Deeply lobed

Origin

California