Vertically grooved bark
Pedunculate (English) oak
Leaves have 3-6 lobes; leaf stalk very short (2-10 mm)
Crown widely spaced. Main root (“tap root”) extends down to approx the height of the tree (unlike the roots of the beech which spread horizontally).
Oak remains green for longer than many other deciduous trees.
Sessile (Durmast) oak
Leaves have 4-8 lobes; leaf stalk longer than in English oak, at 1-3 cm
Leaves almost fern-like: more lobes than pedunculate or sessile oaks – and deeply divided:
Insect galls on oak trees
Female gall wasp uses a long (needle-like) ovipositor to lay a single egg within an oak bud. Unidentified chemicals in the egg or substances injected with it, switch on a set of genes belonging to the tree. This, as a result, induces a tumour-like growth on the surface of the oak leaf. Each will contain a single gall wasp larva.
Common spangle gall
Found on the underside of oak leaves
Silk button spangle gall
Often very numerous with over a thousand per oak leaf.
Contains a small egg-shaped gall which contains a single wasp.
It’s a useful site, sure I’ll revisit it when I need to identify galls. Great clear photos + info. Thank you, Georgina.