Hazelnuts are deciduous; their leaves are alternate, serrate, obovate, and hairy. The plants range from 3 to 36 metres (10 to 120 feet) in height. In late winter a profusion of yellow male catkins and smaller red-centred clusters of female flowers appear on the same tree. The roundish or oblong brown nut, usually 1 to 4 cm (0.5 to 1.5 inches) long, is partly or wholly enclosed in a husk. The plants are deep-rooted moderately shade-tolerant trees that fruit best in well-drained soil and in full sun.