The legume family of plants, Fabaceae, has many genera of which Brachysema was only one. Quite recently all members of Brachysema were transferred to Gastrolobium. For convenience, the species will be referred to as Brachysema here, rather than duplicating the terms Brachysema and Gastrolobium throughout the article.
The ten species which belonged to Brachysema are all endemic to the south-west of Western Australia. Brachysema are mostly found in sandy, infertile soils. In the main, they are small, spreading shrubs or prostrate creepers. The leaf arrangement may be opposite or alternate simple leaves. The prostrate types are useful ground covers. Brachysema have pea-flowers. The typical pea-flower consists of four petals. The flowers are mainly red but cream, yellow-green and dark, almost black, flowers occur as well. They are full of nectar and favourites with birds.
Brachysema lanceolatum has the synonym B.celsianum and is also known as the dark bush-pea, or the Swan River Pea. It spreads to 3 metres and has grey-green to dark green leaves with silvery undersurfaces. Red flowers appear along the branches mainly from June to October. It is a hardy shrub, suited to a wide range of conditions. It blooms best if grown in a sunny position.
Another prostrate species is Brachysema sericeum (G. sericeum). It is variable in habit but is usually low and spreading. As a groundcover it is 0.5 metres high with a spread of about 1 metre. The leaves vary from elliptical to round and are about 5cm long. The pea-shaped flowers are usually either a pale yellow-green, cream or blackish. The flowering season extends from July to January. It prefers a fairly well-drained soil in filtered or partial sun although it will tolerate full sun. This species is fairly adaptable to a wide range of soils. It does, however, need good drainage and either full sun or semi-shade.
Many natives from Western Australia will not tolerate the humid conditions found on the eastern part of the continent, however this plant is better suited to such humidity. It attracts honey-eating birds and tolerates moderate frosts.
Brachysema modestum or broad-leaved Brachysema occurs near Busselton, south of Perth on the edge of the Whicher Range. It is a broad-leaved shrub which reaches 0.5m high and spreads to 3 metres. Prostrate stems form runners and (often) the plant will root at the nodes. The leaves are large and glossy and the flowers may be hidden amongst the foliage. The plants flower from September to November bearing cream to pale green flowers which are infused with pale pink.
Most Brachysema will tolerate a wide range of conditions but a sunny site and well-drained soil will suit them best. They will tolerate short periods of dryness. Like many natives, they cannot cope with high levels of phosphorous. When flowering has finished for the year, the plants will benefit from a light pruning.