THE BIOLOGY OF CANADIAN WEEDS - 109 - CYTISUS-SCOPARIUS (L.) LINK

Scotch broom (Cytisus scoparius [L.] Link.) is an exotic perennial, le guminous, deciduous shrub, which during the past century has greatly e xpanded its range along the Pacific and Atlantic coasts of North Ameri ca, and in Australia, New Zealand, South Africa, Chile, Iran, and Indi a. This shrub rapidly invades disturbed areas, forming dense thickets, which can suppress and inhibit native vegetation, including economica lly important conifer seedlings. The developmental characteristics whe reby Scotch broom invades new sites include specialized stem photosynt hesis, prolific seed production, longevity of seeds in the soil, and n itrogen fixation. Human activities such as planting along highways for beautification and prevention of soil erosion have accelerated the pr oblem of rapid geographical dispersal. Various methods of control (che mical, manual, and biological) together with habitat, morphology, repr oductive biology, growth and development are discussed.