The botanical name for the green bird flower is crotalaria cunninghamii. Crotalaria; from Greek crotalon, a rattle, referring to the seeds which rattle in the pod. cunninghamii; After 19th century botanist, Allan Cunningham.
The "pea" family of plants is a large group of over 500 genera and over 12,000 species which occurs throughout the world and which consists of herbs, shrubs, trees and climbing plants. Some exotics, such as the edible peas and beans, clover, lucerne and sweet peas are well established as commercial or ornamental crops while others, such as English broom (Cytisus scoparius) and gorse (Ulex europaeus), have long since outlived their welcome in some areas and become environmental weeds.
The pea-flowered plants are legumes and are able to take-up ("fix") their nutrient requirements for nitrogen directly from the atmosphere with the aid of soil bacteria (Rhizobium spp.). This occurs in nodules on the roots of the plants. The pea flowers are not the only plants capable of this - the wattles (Acacia sp.) and the sennas (Senna sp.) and their relatives are also legumes.
Crotalaria is a large genus of over 500 species; there are about 30 native to Australia and a number of exotic species have become naturalised. They are generally small to medium shrubs or herbaceous species and are known as "rattlepods" because the seeds are loose in the pods. Some species contain toxins which accumulate in the liver and produce long-term damage which is often fatal.
C.cunninghamii is a shrub to about 3 metres tall with hairy branches and foliage. The leaves are oval shaped and about 30 mm long. The large, greenish pea flowers occur in winter and spring on long spikes at the ends of the branches. The flowers are streaked with fine, black lines. The seed pods are up to 40 mm long.
The sap from the leaves of this species were used by aborigines to treat eye infections.
Green bird flower is reasonably popular in cultivation in warm areas. It requires well drained soils and prefers a position in full sun. It is not suited to cold climates and is damaged by frost.
Propagation is from seed, which germinates readily after treatment in boiling water, or from cuttings.
Information source: Association of Societies for Growing Australian Plants