The hazel - scientific name Coryalus avellana - is a tree with many uses. It is often coppiced, a type of woodland management that encourages regrowth. Not only can hazel be made into baskets, hurdles, charcoal and pea sticks, it also creates an important habitat - and a food source - for a large variety of insects, birds, moss, lichen, and other wildlife. It is monoecious, which means that that both male and female flowers grow on the same tree.
Hazel is easily recognised by its hairy, oval leaves, jagged at the edge with a pointy tip, catkins in the spring and, of course, its nuts, or cobs. Look out for hazel coppices, too, where you'll see each tree with multiple stems.