Although many of the leaves have fallen, oak leaves sometimes overwinter on the tree due to their high tannin content. A comparison of leaves shows the difference in petiole (leaf stalk) length between the three common species. The book on which they rest acts only as a contrasting background.
English or European Oak has no leaf stem (petiole) and the base of the leaf has ‘ears’ on either side of the stumpy petiole. Leaves are about 10cm long tending to grow in bunches as in the example below.
Sessile Oak is the native UK species. These examples come from the trees growing in an area of semi-natural ancient woodland in Armstrong Park. It is distinguished by its stalked leaves and acorn cups. Quercus robur and Q petraea often hybridize to produce intermediate forms with characteristics of both species. The hybrids often have larger leaves.
The third common species is the Turkey Oak (Q cerris), introduced in the 18th century, it has longer irregularly shaped leaved with long stalks. The Turkey oak plays host to the gall wasp (Andricus quercuscalicis), whose larvae damage the acorns of native British oaks. The resulting distorted Knopper galls are frequently found in the Dene scattered on the ground.
This Lucombe Oak is another cross and is a hybrid evergreen although some leaves fall in the Autumn. There is a specimen in Armstrong Park near the windmill. It can be identified by the whisker hairs on the on the tips of the end buds as shown below.
The Lebanon Oak along Red Walk has slender glossy leaves with bristle-tipped triangular lobes.
With large red leaves and whiskered teeth, the Red Oak leaf is unmistakable. There is a splendid example in Coleman’s field.
The Pin Oak, another North American import, has smaller leaved than the Red Oak with buff drifts of hair under the vein joints.
Oak buds, from which next years leaves will emerge, are bunched at the twig tips.
Collins Tree Guide 2006