There are 30+ varieties in the Quercus group, all producing acorns of differing sizes. Some stay on the tree for 2 years before dropping. Some are edible, with low levels of Tannin.
A deciduous tree growing to 30 m (98ft) by 30 m (98ft) at a slow rate. It is hardy to zone 4. It is in flower from Apr to May, and the seeds ripen from Sep to October. The flowers are monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and are pollinated by Wind. It is noted for attracting wildlife.
Prefers a good deep fertile loam which can be on the stiff side. Young plants tolerate reasonable levels of side shade. Succeeds in heavy clay soils and in wet soils so long as the ground is not water-logged for long periods. Dislikes dry or shallow soils but is otherwise drought tolerant once it is established. Tolerant of exposed sites though it dislikes salt-laden winds. The oak is a very important timber tree in Britain, it is also a very important food plant for the caterpillars of many species of butterfly, there are 284 insect species associated with this tree.