There are but two species in New Zealand which grow only in water. One is the common Azolla, and the other the rarely found Pilularia. Neither of these is very fern-like. Azolla filiculoides, var. rubra, is found as a thick covering over large areas of ponds and slowly moving streams. Each plant is very small with overlapping leaves which enclose air and this enables the plant to keep above water. Pilularia novaezealandiae has tiny grass-like leaves; the spores are in small rounded structures resembling “pills”.