Pinus banksiana Lamb. Jack Pine Native to Canada and north-eastern United States, cultivated for timber on poor sandy soils in central Europe. Height to about 21m (70ft) though may be shrubby in cultivation. Flowers open in May, males yellow or reddish yellow, clustered at base of new growth, females red and prickly, about 0.5cm (1/5in) long. Cones are about 3.7cm (1½in) long, very tapered and usually curved. They ripen from green to light brown and although some cones open on the tree, most remain closed until triggered by the heat of a fire. Seeds therefore become viable after a forest fire so Jack Pine is often one of the first trees to colonise burnt areas. Needles are short, 2-4cm (¾-1½in), flattish and grouped in pairs. Z2.