FZ volume:0 part:0 (1970) Selaginellaceae by E. A. C. L. E. Schelpe
Usually 1 genus only, Selaginella, is recognized
Terrestrial herbs, annual or perennial. Steins erect, decumbent or creeping, bearing aerial roots (rhizophores); primary and secondary branch systems often regular in shape forming a pseudofrond. Leaves ligulate (i.e. with microscopic tongue of tissue on adaxial base), small, thin, either spirally arranged and ± similar in shape and size or in two ranks, those in the centre facing uppermost (the median leaves) and those below on either side (the lateral leaves). Sporangia dehiscent with 2 valves, borne singly in axils of specialised leaves (sporophylls) arranged in strobili (which may or may not be dorsiventral); sporophylls may be similar or dimorphic as in the leaves. Spores of 2 kinds, borne in separate sporangia. Megaspores, of which there are usually 4 (rarely 1 or 8) in each sporangium, trilete, laesurae usually forming a 3-radiate ridge reaching an equatorial ridge; on germination give rise to prothalli bearing female organs (archegonia) only. Microspores trilete or more rarely monolete, laesurae usually less distinct, produced in large numbers in each sporangium, giving rise to prothalli bearing male organs (antheridia) only.