ALT Tree no. 16894 Pedunculate oak (Quercus robur) English oak Large deciduous tree with a broad and spreading crown, native to the British Isles and Europe. It has round-lobed leaves with smooth edges and short stalks (petioles). A monoecious species – the male flowers form long, yellow, hanging catkins and female flowers resemble small pink buds, which are wind pollinated to produce acorns. A pioneer species in plains and hills, pedunculate oak is tolerant to soil conditions and can improve soil structure and drainage. The wood has a high tannin content, making it resistant to insects and fungal attacks. Oak decline may be caused by mildew, and acorns are often affected by knopper gall. The trees host hundreds of insect species, with mammals feeding on acorns and birds nesting in crevices in the bark. A fair amount of light passes through the canopy, supporting a rich diverse understory.