c 
of the Anatomy of the Genus Selaginella , Spr. 187 
F. Lyallii Type . 
The solitary form which I describe in this section is con- 
sidered by Baker as a variety of S. laevigata , Baker, I have 
made several attempts to obtain S. laevigata itself in a fresh 
state, but without success. Under these circumstances I have 
thought it best to designate the section by the name of the 
variety, for it does not follow, as I have shown above, that 
outward resemblance is accompanied by identity or even 
similarity of internal structure. 
53. Selaginella laevigata , Baker ; var. Lyallii , Spr. Baker’s 
Handbook, No. 251. 
Baker describes this plant as having e Stems erect, i-i| 
feet long, simple in lower half, the leaves small, distant, and 
soon deciduous, deltoid in the upper half, with petioled deltoid 
1-2 pinnate pinnae. 5 He makes no mention in the diagnosis 
of the marked distinction to be seen between the erect stems 
and the short zigzag rhizome. Spring speaks of the stem as 
c e basi repente radicante erectus. 5 The distinction between 
creeping and erect stem is emphasized by the marked ana- 
tomical differences between those two portions of the axis. 
Indeed, the differences are so great that the two parts might 
well belong to different genera. The stem has again and 
again been referred to, though briefly, in anatomical works, 
but the descriptions apply to the erect stems only, the creeping 
stem not even being mentioned (PI. XII, Figs. 77 and 79). 
The anatomy of the stem as a whole will perhaps be most 
readily understood by commencing with a consideration of 
the branch system. 
1. Anatomy of a branch-system . 
If the stelic system of a terminal pinna be isolated in the 
usual manner, it will be found (PI. XII, Fig. 78) that there are, 
to start with, two distinct steles, each with pericycle, endo- 
dermis, and lacunar tissue. Each has a phloem-area and one 
protoxylem-strand only, derived from the fused leaf-traces of 
the leaves of the dorsal and ventral leaves. Very soon, and 
before the fusion with the stelic system of the first branch, the 
