2 3 6 
PHARMACEUTICAL BOTANY 
and descend the neck canal, one fertilizing the egg by uniting with 
it. This completes the sexual or gametophyte generation. The 
fertilized egg now undergoes division until an elongated stalk 
bearing upon its summit a capsule is finally produced, this being 
known as the sporogonium. The base of the stalk remains imbedded 
in the basal portion of the archegonium, at the tip of the leafy 
stalk, and forms a foot or absorbing process. In growing upward 
the sporogonium ruptures the neck of the archegonium and carries 
it upward as the covering of the capsule, or calyptra. The calyptra 
is thrown off before the spores are matured within the capsule. 
The upper part of the capsule becomes converted into a lid or oper- 
culum at the margin of which an annulus or ring of cells forms. The 
cells of the annulus are hygroscopic and expand at maturity, 
throwing off the lid and allowing the spores to escape. This com- 
pletes the asexual or sporophyte generation. The spores falling 
to the damp soil germinate into protonemata, thus completing 
the life cycle in which is seen an alteration of generations, the two 
phases, gametophyte alternating with sporophyte. 
DIVISION III. PTERIDOPHYTA 
The most highly developed cryptogams showing a distinct alter- 
nation of generations in their life history. They differ from the 
Bryophytes in presenting independent, leafy, vascular, root-bearing 
sporophytes. 
SUBDIVISION I. — LYCOPODINE/E OR CLUB MOSSES 
Small perennial, vascular, dichotomously branched herbs with 
stems thickly covered with awl-shaped leaves. The earliest forms of 
vascular plants differing from ferns in being comparatively simple in 
structure, of small size, leaves sessile and usually possessing a single 
vein. Except in a few instances the sporangia are borne on leaves, 
crowded together and forming cones or spikes at the ends of the 
branches — Homosporous. 
Family I. Lycopodiaceae, including the single genus Lycopodium 
with widely distributed species. The spores of Lycopodium clava- 
tum are official. 
