Sessile Oak Also known as the Irish or durmast oak, Quercus petraea is a tall, deciduous, very long-lived tree with a broad, rounded crown and an upright habit. The leathery, rather shallowly lobed leaves are deep green, turning brownish-orange in autumn; they have a long leaf-stalk. Inconspicuous greenish male catkins and tiny red female flowers appear with the young leaves, and are followed by acorns, whose scaly cups sit directly on the twigs; acorns are not usually borne until the tree is over 40 years old. Sessile oak is a wonderful tree for wildlife; the leaves are larval food for the purple hairstreak butterfly and many other insects, providing food for birds, and the acorns are winter food for jays, badgers and squirrels – and, long ago, pigs and wild boar. The leaves rot down quickly, supporting insects and many fungi. As long as the soil is well-drained (it won’t tolerate waterlogged soil) sessile oak will tolerate hilly sites and poor, acid soil, but it does need plenty of light. Site: Tolerates exposure and hilly sitesSoil: Any well-drained soil, preferably moist and fertilePosition: Full sun or partial shadeSeason of interest: Spring to autumnHardiness: Extremely hardyHeight: 66-130’ (20-40m) Spread: 66’ (20m) or broader in 50 years