KEY TO THE ORDERS AND GENERA.
Series I. ISO S P O B IA .— Spores all of one kiiiil, falling to the
gromid and qiroducing independent qirotliallia, ou whicli are
developed antheridia and archegonia.
Order I. F IL IC E S .— Stems solid, producing leafy fronds with
copious and often complicated venation. Sporangia usually
arranged in clusters (sori) on the back or edge of leafy fronds,
rarely in spikes or panicles. Spores without elaters. Vernation
circinate.
Order II. EQ U ISE TA C EÆ .— Stems hollow, destitute of proper
leaves ; nodes distinct, each furnished with a short toothed sheath;
branches, if present, usually verticillate. Sporangia placed on the
underside of peltate scales, which form a cone at the end of the
stem. Spores furnished with four long elaters, clubbed at the end.
Vernation not oiroinate.
E q u i s e t u m .— The only genus. Page 1 .
Order III. LYCOPODIACEÆ.— Stems solid, usually furnished
with copious small leaves with simple veining. Sporangia solitary
in the axils of ordinary or modified leaves. Spores without
elaters. Vernation oiroinate.
*Accmlesceni.
1. P h y l l o g l o s s u m .—Leaves all iu a radical rosette. Sporangia
in a dense spike at the end of a leafless peduncle. Page 7.
** Caulescent.
2. L y c o p o d iu m . — Sporangia orbicular, compressed, 1-oelled,
2-valved. Leaves small, crowded. Page 7.
3 . T m e s i p t e b i s . — Sporangia boat-shaped, 2-oelled, 2-valved.
Leaves longer, less crowded. Page 29.
4. PsiLOTUM.— Sporangia turbinate, 3-oelled, 3-valved. Leaves
distant, rudimentary. Page 80.