Salix fragilis L. Crack Willow or Brittle Willow. Native to Europe (including Britain) and west Siberia south to Iran, growing on riverbanks. Twigs snap off easily at their bases when knocked, hence the common names. This allows it to spread along a river as they root and form new plants when washed ashore. Height to 25m (80ft). Catkins open in April, males yellow about 1.8-5cm (¾-2in) long. Female catkins are green developing to fruiting catkins about 10cm (4in) long which release white fluffy seeds in May. Leaves are narrow and coarsely toothed, slightly hairy at first but turning glossy green and hairless when mature. Z5.