In Selaginella the stelar systeim h do~ shows profounder modifications.
The first formed portion of the stern in all species of Selaginella which have been investigated possesses an exarch haplostele.
The leaves of the true mosses and those of the club-mosses (Lycopodium, Selaginella) being somewhat alike in general appearance and in ontogeny, might be, and indeed have been, regarded as homologous on that ground.
The country in general is a fern paradise, and the iridescent creeping Selaginella (akin to Lycopodium) festoons the undergrowth by the wayside.
The single genus of this order (Selaginella) contains between three and four hundred species.
Selaginella is heterosporous, the megasporangia being often found towards the base of the cone.
Thus the position of the root in Selaginella is different from what obtains in the other Vascular Cryptogams. A point of interest in this heterosporous genus is that the formation of the prothallus may commence before the megaspore is liberated from the sporangium.
The cones, which in some instances at least were heterosporous, presented a general resemblance to those of Lycopodium and Selaginella, a single sporangium being situated on the upper surface of each sporophyll.
Each leaf bears a ligule resembling that of Selaginella in structure and position.
The spores, which are set free by the rotting of the sporangial wall, germinate much as in the case of Selaginella, though the similarity may be a case of independent resemblance.