Mamane is a large shrub or medium sized tree that can grow up to a height of about 50'. Pea-like yellow flowers form loose bunches at the base of leaves or the ends of branches. Orange seeds form inside pods, and are sometimes collected and used to make leis.
Mamane seeds are the primary food source of the palila (Loxioides bailleui), an endangered Hawaiian bird species. Mamane forests on Mauna Kea have become degraded by browsing pressure from introduced goats and sheep. In recent years federally mandated eradication of feral herbivores has improved the condition of Mamane trees by reducing browsing by goats and sheep.