Terrestrial, annual or perennial, moss-like plants with branching stems and scale-like leaves, which are,many-ranked and uniform, or 4-ranked and of two types spreading in two planes. Sporanges 1-celled, solitary in the axils of leaves which are so arranged as to form more or less quadrangular spikes, some containing 4 megaspores (megasporanges), others containing numerous microspores (microsporanges), which develop into small prothallia, those from the megaspores bearing archegones, those from the microspores antherids.

The family consists of the following genus: