3 Costus woodsonii

Costus woodsonii.

Red button ginger are perennial clumping herbs to shrubs up to 2 (4) m high.
Growing from underground rhizomes the cane-like stems are slightly spirally twisted.
The erect to arching stems are fleshy.

The simple alternately arranged leaves are in a spiral.
The base of the blade narrows for a few mms then runs down the stem as a sheath.
The edges of the sheath are closed and there is a ligule at the top of the sheath.
The leaves are around 20 to 30 cm long with a pointed tip and a wedge-shaped base.

The terminal inflorescence is a spike with red overlapping bracts in a spiral.
Young inflorescences are ovoid but they grow into a narrow cylindrical spike up to 15 cm long.

The waxy bracts are bright red and each holds 1 tubular flower that only lasts 1 day.
Flowers are up to 3 cm long with 3 orange sepals.
The 3 orange, reddish to yellow petals are fused into a tube with lobes as long as the tube.

There is 1 fertile yellow stamen 3 cm long.
The 5 infertile staminodes are fused into a large yellow to orange petal-like labellum.
The petals and labellum only open for a few mms at the tip.

Nectaries on the outer surface of the bracts attract ants that protect the flowers.
Bulbils sometimes grow from the base of an old inflorescence.