scotch broom
Scotch Broom (Cytisus scoparius) is an erect, deciduous shrub to 4 metres high, with 5-angled branchlets. Leaflets are narrow-elliptic to oval with the broadest part in the upper half. The terminal leaflet is longer than the side leaflets, 4-20 mm long, 1.5-8 mm wide with the tip sharply pointed or round. Young leaves are often silky hairy on both surfaces, but sometimes hairless.
This species is widely naturalised in the coastal and sub-coastal regions of south-eastern Australia. It is most common in southern and central New South Wales, south-eastern South Australia, Victoria and Tasmania. Also scattered in north-eastern New South Wales and other parts of South Australia, and possibly naturalised in Western Australia.
Mainly a weed of temperate regions that infests open woodlands, scrublands, grasslands, forestry plantations, pastures, waterways, coastal environs, roadsides and waste areas.
An upright (i.e. erect) shrub usually growing 1.2-2 m tall, but sometimes reaching up to 4 m in height.
It forms dense stands, which shade out the ground flora, and roadside infestations can also reduce drivers' vision and increase road maintenance costs. It commonly establishes in disturbed margins of native vegetation, from where it invades less disturbed native vegetation. Infestations also provide shelter for pest animals such as pigs and horses, which in turn pose a threat to native biota. It has invaded disturbed areas in national parks which have been cleared of blackberry infestations.
Leaflets are narrow-elliptic to oval with the broadest part in the upper half. The terminal leaflet is longer than the side leaflets, 4-20 mm long, 1.5-8 mm wide with the tip sharply pointed or round. Young leaves are often silky hairy on both surfaces, but sometimes hairless.
Flowers are usually 1 or 2 per junction between the stem and leaf stalk and deep-yellow. Occasionally they may be tinged with red or mauve or variously coloured in many cultivars, including white, cream, or with brownish-crimson lateral petals and a yellow upper petal The fruit is narrow, 25-60 mm long, 8-10 mm wide, flattened, silky hairy, turning black at maturity with 6-18 seeds released explosively when ripe.
Scotch Broom is spread solely by seeds, which are ejected explosively as the pods dry out on warm, sunny days during summer. Most of the seeds fall within a few metres of the parent plant. They are further dispersed by water (particularly if near streams), mud on machinery (such as road graders and slashers), vehicles and footwear. Birds, ants, cattle, horses and animal diggings are other means of dispersal (Parsons & Cuthbertson 1992; Muyt 2001).
Spanish Broom (Cytisus multiflorus) C. x dallimorei Rolfe, and C. x praecoxBean. C. x dallimorei is a hybrid between white Spanish Broom and English Broom (seed parent).
