Trees to look for in September — Oak / Acorn

There are two native British species of oak tree – English Oak (Quercus robur) and Sessile Oak (Quercus petraea). They are wind pollinated and have separate male and female flowers (catkins) on the same branch. When the catkins are pollinated they form seeds, which are known as acorns. The English Oak doesn’t produce acorns until it’s at least forty years old! The cup-shaped base of the acorn is called the cupule and when the acorn is ripe it will fall from the cupule on to the ground, where it will either grow into a new tree or be eaten by many different animals including squirrels and jays. Oaks trees support more living things than any other native tree, including 350 different species of insect. A single oak tree may have more than 30 different lichen species on its bark!  It can be difficult to tell the difference between the two types of oak, but there are small differences in the acorns. The acorn stalks are longer in English Oak (2 to 9 cm) while sessile oak acorns sometimes don’t even have stalks and where they do, they are much shorter (3-4 cm long).

For more info see
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/english-oak/
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/sessile-oak