Spike mosses mainly have a tropical distribution, growing in moist shaded habitats, aithough a few are found in deserts. They are
terrestrial,
perennial or
annual plants, without true roots. The stems are usually branched, with small simple leaves that are arranged in four rows, with two rows having long leaves, and two with small leaves. A small outgrowth called
ligule is located on the upper surface of each leaf, close to where it joins the stem.
These plants are
heterosporous, that is it reproduces through two type of spore.
Sporangia are borne by specialised leaves called
sporophylls, which are usually aggregated into
strobili.
Microsporangia produce many
microspores, which
germinate to form short-lived
microgametophytes that produce sperm.
Megasporangia produce a few larger
megaspores each, and these form
megagametophytes that produce eggs in specialised organs called
archegonia. To reach an archegonium and fertilise an egg, a sperm cell must swim in a film of water.
New Zealand has no native species in the Selaginellaceae family. Unfortunately one species
Selaginella kraussiana has been introduced and has become naturalised. It can be found in lowland forest in the North Island along walking tracks, and beside streams. It's a serious nuisance in many places, pushing out native species.