Perennial small tufted herbs, glabrous or with scattered marginal hairs on leaves. Leaves opposite (but often appearing more or less rosetted), linear, connate at the base, forming a short cup; stipules absent. Flowers solitary, terminal, pedunculate, 4- or 5-merous, bisexual; sepals 5, free; petals absent; stamens 4 or 5; ovary 1-celled; styles 4 or 5. Fruit a capsule opening by terminal valves; seeds numerous, ovoid to cuneate, with very small rounded papillae (in Victoria).
20 species, native in South America, South Georgia, the Antarctic Peninsula, New Zealand, Australia and sub-Antarctic islands; 6 or 7 species on mainland Australia and Tasmania; 3 species on Macquarie Is. and 1 on Heard Is.
The genus is currently under revision.