About 15 species of perennials from North and South America, Madagascar, Australia and New Zealand. They have slender rhizomes which creep at, or just below ground level, rooting at the nodes from which arise one to several somewhat rush-like structures known as phyllodes (modified bladeless leaf stalks). Cylindrical, spathulate or awl-shaped, the phyllodes are hollow but divided into segments by a series of horizontal membranes (septa). The tiny five-petalled flowers are borne in umbels amongst the phyllodes and are insignificant. In general, the species are rather similar and identification is largely by seed (botanically fruit) shape and size. All the species described form patches or colonies rather like a small rush or grass.
Although botanically interesting this genus is singularly lacking in beauty. On the other hand, its species do intrigue and puzzle alpine gardeners and give opportunity for one-upmanship. Most, if not all species need moist humusy soil and good light. Propagation by division in early spring or autumn, and seed when ripe or as soon afterwards as possible.