Marsh or water plants, with creeping rhizomes, solid cylindrical stems, and long linear leaves sheathing at the base. Flowers minute, moncecious, densely crowded in globose or cylindric spikes or spadices, male spadices always uppermost. Perianth either wanting or of minute scales or hairs. Male flowers: Stamens 1–7; filaments slender, distinct or connate; anthers basifixed, erect, linear or oblong. Female flowers: Ovary superior, sessile or stalked, 1- or rarely 2-celled; styles as many as the cells, linear, persistent; stigma unilateral, papillose; ovules solitary. Fruit dry or spongy, indehiscent. Seed solitary, pendulous; albumen copious, fleshy or farinaceous; embryo terete, axile.

A small order, cosmopolitan in its distribution, consisting of the 2 genera found in New Zealand and from 20 to 25 species.

Flowers in dense cylindric spikes, the females enveloped in soft downy hairs	1. Typha.
Flowers in globose heads. Perianth of linear scales	2. Sparganium.