e yellow powder. These
capsules are the spore cases.

The bases of the upright stems are almost bare, but become covered
with leaves higher up. The leaves are in shape like those of a moss,
but are thicker. The spore-bearing leaves are broader and when
slightly magnified show a toothed margin.

The stem is traversed by a central fibro-vascular cylinder that
separates easily from the surrounding tissue, owing to the rupture of
the cells of the bundle sheath, this being particularly frequent in
dried specimens. When slightly magnified the arrangement of the
tissues may be seen (Fig. 73, _E_). Within the epidermis is a mass of
ground tissue of firm, woody texture surrounding the central oval or
circular fibro-vascular cylinder. This shows a number of white bars
(xylem) surrounded by a more delicate tissue (phloem).

On magnifying the section more strongly, the cells of the ground
tissue (_G_) are seen to be oval in outline, with thick striated
walls and small intercellular spaces. Examined in longitudinal
sections they are long and pointed, belonging to the class of cells
known as "fibres."

[Illustration: FIG. 73.--_A_, a club moss (_Lycopodium_), x 1/3. _x_,
cone. _r_, root. _B_, a cone, x 1. _C_, single scale with sporangium
(_sp._). _D_, spores: i, from above; ii, from below, x 325. _E_, cross
section of stem, x 8. _f.b._ fibro-vascular bundle. _F_, portion of
the fibro-vascular bundle, x 150. _G_, cells of the ground tissue,
x 150.]

The xylem (_F_, _xy._) of the fibro-vascular bundle is composed of
tracheids, much like those of the ferns; the phloem is composed of
narrow cells, pretty much all alike.

The spores (_D_) are destitute of chlorophyll and have upon the
outside a network of ridges, except on one side where three straight
lines converge, the spore being slightly flattened between them.

Almost nothing is known of the prothallia of our native species.

The second order (_Ligulatae_) is represented by two very distinct
families: the smaller club mosses (_Selaginelleae_) and the quill-worts
(_Isoeteae_). Of the former the majority are tropical, but are common
in greenhouses where they are prized for their delicate moss-like
foliage (Fig. 74, _A_).

[Illustration: FIG. 74.--_A_, one of the smaller club mosses
(_Selaginella_). _sp._ spore-bearing branch, x 2. _B_, part of a stem,
sending down naked rooting branches (_r_), x 1. _C_, longitudinal
section of a spike, with a singl