Garry oak

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The Garry Oak (Quercus garryana), also known as Oregon White Oak or Oregon Oak, has a range from southern California to extreme southwestern British Columbia. It grows at 60-210 m altitude in the north of the range in British Columbia, and at 300-1800 m in the south of the range in California.

A Garry oak grove

It is a drought tolerant tree, typically of medium height, growing to around 20m (occasionally as high as 30m) or just a shrub to 3-5 m tall, with the characteristic oval profile of other oaks when solitary, but is also known to grow in groves close enough together that their crowns form a canopy. The leaves are deciduous, 5-15 cm long and 2-8 cm broad, with 3-7 deep lobes on each side. The flowers are catkins, the fruit an acorn 2-3 cm (rarely 4 cm) long and 1.5-2 cm broad.

The Oregon White Oak is commonly found in the Willamette Valley hosting the American Mistletoe (Phoradendron flavescens). It is also commonly found hosting a green or yellow ball of up to 5 cm in size, attached to the underside of some of the leaves. This abnormal growth (a gall) is formed by the oak around a colony of wormlike larvae belonging to one of several species of tiny wasps. The most common species responsible for these galls is Cynips maculipennis.

There are three varieties:

• Quercus garryana var. garryana – tree to 20 (30) m. British Columbia south along the Cascades to the California Coast Ranges.
• Quercus garryana var. breweri – shrub to 5 m; leaves velvety underneath. Siskiyou Mountains.
• Quercus garryana var. semota – shrub to 5 m; leaves not velvety underneath. Sierra Nevada.

History and uses

Gall on Garry oak, Sonoma County

Before the European settlers came into the Willamette Valley, the oaks were mostly open-grown individual trees due to periodic summer wildfires, and the burning practices of the native Calapuya people. Since the settlers did not continue this practice, and actually suppress most naturally occurring fires, the intervening land was soon covered with seedling oaks (called "oak grubs" by the pioneers) which grew vertically and formed a closed canopy. Remnants of the old open-grown oaks are still found in these closed oak stands.

The Garry Oak has not historically been regarded as having any commercial value, and is frequently destroyed as land is cleared for development. However, recently the wood, which is similar to that of other white oaks, has been used experimentally in Oregon for creating casks in which to age wine.

References

• [Flora of North America: Quercus garryana]
• [Plants of British Columbia: Quercus garryana]
• [Jepson Flora Project: Quercus garryana]
• [Garry Oak Ecosystem – Province of British Columbia - Ministry of Environment] [PDF]

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