oak

The English oak is the most common oak species in Northern Europe. Its lobed leaves and small acorns are characteristic of the deciduous oaks of cool temperate regions. Oaks from warmer regions are usually evergreen and often have unlobed leaves.

Wistman's Wood, Dartmoor, Devon. Wistman's (or Wiseman's) Wood is one of only three remaining ancient upland oak copses in Devon. Originally, oak and birch forest covered all but the very highest reaches of the moor.

Any of a group of trees or shrubs belonging to the beech family, with over 300 known species widely distributed in temperate zones. Oaks are valuable for timber, the wood being durable and straight-grained. Their fruits are called acorns. (Genus Quercus, family Fagaceae.)

The 60 species of North American oaks are divided into two groups: white oaks and red oaks. Most white oaks have leaves with rounded lobes, and their acorns are sweet and mature in one season. Red oaks characteristically have spiny, pointed lobes on their leaves, and their bitter acorns take two years to mature. The white oak (Q. alba) of the eastern US and the northern red oak (Q. rubra) are typical examples. The evergreen live oaks (such as Q. virginiana) form a subsection in the red oak group.

According to the European Commission's annual tree survey for 1998, nearly three-quarters of European oaks (Quercus robur) had declined in health during the period 1992–97. Causes of decline included pollution, fungus, drought, and insects.