Jersey the island. The species is the subject of an ongoing programme to save it from extinction in Jersey via a collaboration between States of Jersey, Durrell Wildlife Conservation Trust and Jersey Amphibian and Reptile Group (JARG), with support and sponsorship from several other organisations. The programme includes captive breeding and release, public awareness and habitat restoration activities. Trees generally considered native are the alder ("Alnus glutinosa"), silver birch ("Betula pendula"), sweet chestnut ("Castanea sativa"), hazel ("Corylus avellana"), hawthorn ("Crataegus monogyna"), beech ("Fagus sylvatica"), ash ("Fraxinus excelsior"), aspen ("Populus tremula"), wild cherry ("Prunus avium"), blackthorn ("Prunus spinosa"), holm oak ("Quercus ilex"),
Prunus pumila leathery, long, with a serrated margin. The flowers are in diameter with five white petals and 25–30 stamens. They are produced in small clusters of two to four. The fruit is a small cherry diameter, ripening dark purple in early summer. "Prunus × cistena" (purple leaf sand cherry) is a hybrid of "Prunus cerasifera" (Cherry Plum) and "Prunus pumila". It was developed by Niels Ebbesen Hansen of South Dakota State University in 1910. Prunus pumila Prunus pumila, commonly called sand cherry, is a North American species of cherry in the rose family. It is widespread in eastern and central Canada