Oaks

Pedunculate Oak Sessile Oak Pedunculate Oak Holm Oak

What are they?

The oaks are a very diverse group of trees with many species around the world, particularly in North and Central America. In Britain we have just two native species, but a number of other species have been widely introduced as ornamentals and for forestry. Oaks are very variable in appearance and the group includes both evergreen and deciduous species, trees with simple leaves and trees with leaves that are deeply lobed, but they are all instantly recognisable by their fruits which are known as acorns.

Where are they found?

Native oaks are widespread throughout East Anglia in most habitats and are also widely planted. A number of introduced species may be found where planted in most kinds of urban and suburban habitats as well as in parkland and roadsides in more rural areas.

Identification

As a group, oaks can be identified by their distinctive fruits (acorns) combined with their winter twigs which have distinctive bud clusters at their tips. Individual species can be recognised fairly easily by looking at their leaves, buds and details of the cups that hold the acorns.



Pedunculate Oak      Quercus robur

Widespread and common throughout the region. A native tree, forming mature woodland on heavier soils and scrub habitats on thinner, drier soils. Also widely planted in hedgerows and parkland habitats. Flowers April to May. Leaves hairless and with distinctly lobed bases and rather short stalks. Acorns carried in clusters of 1-5 on a common stalk (a peduncle).

Pedunculate Oak Pedunculate Oak Pedunculate Oak Pedunculate Oak
Habit
Habit
Leaf
Male flowers
Pedunculate Oak Pedunculate Oak Pedunculate Oak
Female flowers
Acorns
Winter twig


Sessile Oak      Quercus petraea

A native tree mostly of the granite-based soils of western and Northern Britain; scarce in East Anglia on the acidic gravels of the Holt-Cromer ridge and south and east Suffolk. Also occasionally planted elsewhere. Flowers April to May. Leaves with star-shaped hairs on the underside and with unlobed bases. Acorns stalkless or with an only very short peduncle.

Sessile Oak Sessile Oak Sessile Oak Sessile Oak
Leaves
Leaf
Leaves
Stellate leaf hairs
Sessile Oak Sessile Oak Sessile Oak
Acorns
Winter twig
Bark


Hybrid Oak      Quercus x rosacea

The hybrid between Pedunculate and Sessile Oaks is occasionally recorded from areas where the two parents can be found together. Leaves intermediate between the parents but very variable; typically they will show a slightly broader base to the leaf thatn that of Sessile Oak, but with a scattering of star-shaped hairs on the underneath.

Hybrid Oak Hybrid Oak Hybrid Oak
Leaf
Stellate leaf hairs
Young acorns


Turkey Oak      Quercus cerris

Introduced as an ornamental from south-east Europe and widely planted on roadsides and in hedgerows. Flowers May. Leaves relatively narrow and with sharply angled lobes. Acorns with distinctly bristly cups and winter twigs readily told by the bristly bracts between the buds.

Turkey Oak Turkey Oak Turkey Oak Turkey Oak
Habit
Leaves
Leaves
Male flowers
Turkey Oak Turkey Oak Turkey Oak
Acorn
Winter twig
Bark


Holm Oak      Quercus ilex

Introduced as an ornamental from southern Europe and very widely planted on roadsides and in parks, cemeteries and amenity areas. Readily grows from acorns planted by Jays or squirrels and is widely naturalised in coastal dunes and some parkland areas. Flowers May. Grows to become a large and broadly spreading, evergreen tree. Leaves tough and extremely variable, usually being broad and prickly (like holly leaves) on shaded branches and young trees, but typically unlobed on mature trees in sunny situations.

Holm Oak Holm Oak Holm Oak Holm Oak
Habit
Leaves
Leaves
Leaves
Holm Oak Holm Oak Holm Oak
Male flowers
Acorns
Bark


Lucombe Oak      Quercus x crenata

Introduced as an ornamental. A hybrid between Turkey Oak and Cork Oak which occurs naturally in the wild in southern Europe but UK plants are typically artifical hybrids from horticultural stock. Rare, but occasionally found where planted in larger parks or cemeteries. Flowers May-June. Being a hybrid between a deciduous species and an evergreen one, this poor tree appears confused and individuals often drop their leaves in February! Horticultural selections are variable in their bark type and the appearance of their leaves (and the timing of leaf drop). The photos here are of a large tree of variety lucombeana that grows in Earlham Road Cemtery, Norwich, with an open crown and corky bark typical of this variety.

Lucombe Oak Lucombe Oak Lucombe Oak Lucombe Oak
Habit
Leaves
Leaf
Leaf underside
Lucombe Oak Lucombe Oak Lucombe Oak Lucombe Oak
Male flowers
Developing acorns
Winter buds
Bark


Turner's Oak      Quercus x turneri

A hybrid of horticultural origin and occasionally found in parks or cemeteries where planted as an ornamental. A hybrid between Pedunculate Oak and Holm Oak. Flowers May-June. A hybrid between a deciduous species and an evergreen one and very variable in the appearance of its leaves.

Turner's Oak Turner's Oak Turner's Oak
Leaves
Leaf
Leaf detail
Turner's Oak Turner's Oak
Winter buds
Bark


Cork Oak      Quercus suber

Introduced from southern Europe as an ornamental. Doesn't do well in UK winters and the handful of trees are all rather small, in parks or cemeteries. Flowers May-June. An evergreen tree, famous for its bark which is harvested in the Mediterranean to provide cork.

Cork Oak Cork Oak Cork Oak Cork Oak
Leaves
Leaves
Leaf
Leaf detail
Cork Oak Cork Oak Cork Oak Cork Oak
Male flowers
Acorn
Winter buds
Bark


Northern Red Oak      Quercus rubra

Introduced from North America and planted occasionally in forestry blocks, or less often as an ornamental. Flowers May. A deciduous tree with leaves averaging much larger than those of our native oaks (up to 20cm in length) and more sharply angled, with bristle-tips at the ends of the leaf lobes. Underside of leaves hairless except for small tufts of brownish hairs in the vein axils. This is an important distinction from Black Oak (Quercus velutina) which is hairy on the leaf undersides (especially young leaves) and is occasionally planted in the UK, though not yet recorded in East Anglia. Leaves cut no more than half way to the mid vein. Bark only lightly fissured.

Northern Red Oak Northern Red Oak Northern Red Oak Northern Red Oak
Habit
Leaves
Leaf
Leaf underside
Northern Red Oak Northern Red Oak Northern Red Oak
Leaves
Winter buds
Bark


Scarlet Oak      Quercus coccinea

Introduced from North America and planted occasionally as an ornamental. Flowers May. A deciduous tree with leaves averaging larger than those of our native oaks (up to 20cm in length) and more sharply angled, with bristle-tips at the ends of the leaf lobes. Underside of leaves almost hairless with just brownish hairs in the vein axils. Leaves often deeply cut more than half way to the mid vein. Bark fissured and craggy but not flaking easily.

Scarlet Oak Scarlet Oak Scarlet Oak
Habit
Leaf
Leaves
Scarlet Oak Scarlet Oak Scarlet Oak Scarlet Oak
Acorn
Winter buds
Winter buds
Bark