THE FERN ALLIES. 



35 



shaped. As the plant retains this power indefinitely, it has 

 sometimes been called " the Resurrection-plant." 



93. The stems are usually creeping, yet in some species 

 show a tendency to become erect, and most species send up 

 erect branches which bear the fruit. Most species bear roots 

 at irregular intervals along the under side of the creeping stems, 

 Init our solitary species of PsilotiDii is rootless, bearing only 

 underground shoots which perform the functions of roots. The 

 leaves are small and unbranched, in some instances resembling 

 appressed scales, in others resembling the acicular leaves of 

 Conifers, and are arranged in four, eight, or many ranks. In 

 some species the leaves are of one kind, while in others two or 

 even more forms may occur on the same plant. In Psilotum 

 the leaves are all rudimentary. 



94. Fructification. — The fructification of the club-mosses 

 is chiefly borne on upright branches in solitary or clustered 

 (2-5) spikes, which are formed of numerous scales or scale like 

 leaves, each bearing a single large sporangium in its axil. The 

 sporangia open transversely, and are 

 one-celled, except in Psi'lotm/i, where 

 they are three-celled. In a few species 

 of Lycopodiiim the sporangia are borne 

 near the summit of the fertile stems 

 in the axils of ordinary leaves. The 

 usual shape of the fruit-bearing scales 

 is represented in Figs. 24-26. 



95. The spores of Lycopodium 

 and Psiloticin are of one kind (Fig. 24), 

 but in Selagmella two kinds of spo- 

 rangia are developed — the niicrospo- 

 rangia, producing numerous inhro- 

 sporcs (Fig. 25) not unlike the spores 

 of Lycopodium ; and the niacrospo- 

 rangia, producing usually ionr macro- J:^J^^^Jl,:^{^^ 

 s-bores {Y'w. 26), so called from their ^^^^^""Kasporangium m iisaxii. 



^ . Figs. 25, 20. — Scales from fer- 



larger size. This character of Scla- tile spike of Seiagiueiia ruf>es- 



,, , . , . , • 1 , •,, ^'■/j Spring, disclosint; two sorts 



ginella, which it shares with the quill- of spores. (After Sprague.) 

 worts and pepperworts soon to be described, serves as the 

 basis for the division of the fern allies into two groups : the 



