Costus L.

Classical name probably originating from the Arabic Koost.

Low to tall herbs. Stem usually unbranched. Flower cluster dense terminal on leafy shoot or growing from the rhizome. Bracts broad and overlapping, each with 1 or 2 flowers. Calyx mostly 3-lobed. Lip conspicuous, the lateral sterile stamens absent. Fertile stamen filament broad. Ovary 3-chambered. Fruit a white loculicidal capsule, or breaking up irregularly; seeds glossy black or brown.

Tropical rainforest plants which, if grown in pots, require warm, humid conditions. C. potierae is a rare Australian endemic confined to coastal high rainfall lowlands near Rockingham Bay, also Torres Strait islands; it is similar to C. speciosus with the spine tipped bracts but has yellow flowers with a much smaller lip.


A few species are used locally for their medicinal properties.The chemical diosgenin is extracted from the rhizome of C. speciosus.

Sterile stamen lip large, the calyx and perianth relatively small.

Pantropical genus of about 90 species, mostly tropical Central America and Africa, poorly represented in Asia and Australia (2 species, 1 endemic).

Maas (1977).

Source: Spencer, R. (2005). Costaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Lilianae
order      Zingiberales
family       Costaceae
Higher taxa
Subordinate taxa
species         Costus malortieanus H.Wendl.