Other names: Umbrella Sedge.
Family: Cyperaceae (Sedge family).
Native of tropical America.
Occurrence: A widespread and common weed, usually growing in damp places e.g. in drains and gutters and near streams. It is sometimes a lawn weed and invades damp bushland areas.
In dry conditions it may die down, and re-shoot when moisture levels are higher. It is a perennial which spreads from seeds and by underground shoots.
Similar species: There are several moderately common native Cyperus species. The native species are often taller, and have brown to dark brown flowers which are often on more slender stalks
Photos 1: The flower clusters are on long or short stalks.