Gaultheria Shallon (also known as salal) is an evergreen shrub (which grows up to about 1.2m high in favourable conditions) from North America. It spreads mainly by underground roots, but also has berries with seeds that can be spread by birds and animals. Although Gaultheria Shallon is non-native and invasive, it is not listed in the 2018 DEFRA list of species of special concern, so still can be bought and moved. . .