Selaginella are frequently described as primitive or living fossils due to the nature of their physiology and reproduction. They are the only living members of their family, with about 700 species. Selaginella are found in a wide range of environments, from cold temperate to desert to the wet humid tropics. Many of them look like mosses but they differ in significant ways–reproduction being the most obvious.
Selaginella reproduce by the production of two types of spores that combine to produce a new plant.
Mature Plant and Spore
A mature Selaginella produces, on the tips of branches, small structures sometimes referred to as cones but are more properly called strobili. There are two types of strobili that differ in size and color, each having a component for the plant's sexual reproduction. A plant that has both microspores and megaspores is called heterosporous
The largest of these, called megasporangium because of their size, is usually yellow and may appear lumpy. Four large spores can be seen with the help of a magnifying lens. They act as the female component in the reproduction of Selaginella.
The smaller structure is darker, usually orange in color, and not lumpy but oval shaped. This structure is the microsporangium and it contains many, nearly microscopic, spores. These microspores act as the male component in reproduction.
As in ferns, the spore of Selaginella grow into a gametophyte. The gametophyte produced by the large spore in the megasporangium produces egg cells. The small spores in the microsporangium grow into a gametophyte that produces sperm cells.
A film of water is necessary for the sperm to travel to the egg; this is provided in the wild by dew, fog or rain. When the sperm unites with the egg, cell division produces a tiny new plant called a sporophyte. The sporophyte roots to the ground and develops into a plant over time, producing spores to repeat the process when mature.
Sexual reproduction of Selaginella is not considered easy, so asexual reproduction is preferred by most growers.
In asexual reproduction cuttings, of Selaginella are pinned to a rich, well drained, media and will form roots over time. These new plants will continue to grow and produce spores when mature.
Popular Selaginella Species
Some popular Selaginella are: resurrection plant (Selaginella pilifera A. Braun or Selaginella lepidophylla (Hook. & Grev.) Spring ), peacock spike moss (Selaginella cucinata (Desv. ex Poir.) Spring) and gulf spikemoss (Selaginella ludoviciana A. Braun).