Chorizema humile, more commonly known as the Prostrate Flame Flower, is a small, prostrate shrub to approximately 60 cm in diameter.
The many slender stems are rigid with scattered hairs and radiate from a central root.
The leaves are obovate and are up to 16 mm long and up to 5 mm wide, tapering at the base into a short petiole. They are arranged alternately along the stem and have a short awn-like projection at the apex.
The flowers occur at the ends of the stems in racemes up to 18 cm long with up to 30 flowers in each and on stalks up to 2.5 mm long. The petals are yellow with red-brown markings. The standard petal is up to 9 mm long, the wing petals are gently curved to 8 mm long and the keel tapers to a protracted point and is almost as long as the wings.
Chorizema humile is listed as ‘Endangered’ under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and ‘Critically Endangered’ under the Wildlife Conservation Act 1950.
The main threats to the Prostrate Flame Flower are grazing, trampling, road maintenance activities, weed competition and inappropriate fire regimes.
Chorizema humile is found in red loam, brown, sandy clay with decomposing granite or in clay soils, on plains in scrub or open tree mallee. Associated species include Allocasuarina campestris, Hypocalymma angustifolium and several Acacia species.
Chorizema humile is endemic to Western Australia and has historically been collected from Cue to Dowerin.
Some doubt has been cast on historical collections as this species has been misidentified in the past. In addition a search for rare plants in the Cue area conducted in 1999 discovered a Mirbelia species of similar resemblance to C. humile. Prostrate Flame Flower is currently known from 13 populations, all of which occur in the Coorow and Moora areas.
A 2002 study, showed that Chorizema humile is able to survive even after heavy grazing because it can reproduce through shoots, the individuals are long lived and the plants produce enough offspring over time to enable the population to recover.
This study also showed that grazing greatly reduces the amount of flower and fruit produced but there are also other intrinsic, environmental or climatic factors affecting the efficiency of seed set.
Apart from this study little is known about the biology and ecology of C. humile. It is thought that it may be pollinated by bull ants. This species is known to be easily propagated from cuttings.
Information Source: Government of Australia, Department of Environment and Department of Parks and Wildlife Western Australia.