Costus macranthus

Costus macranthus K.Schum.

Costus macranthus is a terrestrial, shootless, rosette-forming herb in the family Costaceae, native to eastern and southern Africa. It is found in Malawi, Mozambique, Tanzania, Uganda, Zambia, and Zimbabwe, growing in non-inundated forests, open grasslands, and rocky soils, often near ant hills, at elevations of 500 to 1700 m. It flowers and fruits from November to December, occasionally extending into January to March.

Description

This species is characterized by a rosette of 3–5 leaves, which are elliptic to suborbicular, fleshy, and have red-purple margins. The leaves form a flat, cruciform rosette on the ground, with a central, few-flowered inflorescence. The rhizomes are vertical, and the plant produces horizontal runners. The inflorescence is enclosed by thickened leaf bases and sheaths. Costus macranthus is distinguished from C. spectabilis by its longer anthers, which are 7–12 mm in length. It is commonly found in the same geographic range as C. spectabilis, but is distinguishable by several morphological traits, including larger flower parts.