‘Koster’ is a fastigiate form with upright branches, spreading with age to ultimately reach approximately 20m high and 3m wide.

It has a slender habit and forms a neat columnar shape when mature.  That is why it is commonly named Cypress oak. The ascending branches are covered in obovate lobed leaves that are mid-dark green in colour; the leaves fade to yellow and bronze before falling in autumn. Young bark is rippled with snake-like markings and when the tree is mature the bark becomes more fissured – which adds great character to this mighty tree. This Oak is a long-lived tree which is perfect for adding structure to a woodland style garden or for bordering a drive or courtyard.