146 EVOLUTION OF PLANTS 
reduced to a single vegetative cell, and a single anthe- 
ridium in which are developed biciliate spermatozoids 
like those of Lycopodium (D). 
In both Lycopodium and Selaginella, the stem of the 
sporophyte is long and extensively branched, while the 
leaves are small and moss-like. The tissues, especially 
the vascular bundles, are not unlike those of the ferns. 
Sometimes the stem and root grow from a single apical 
cell, sometimes a group of initial cells is present, but 
even when there is a single apical cell, it never shows the 
almost mathematical regularity in its divisions found in 
the leptosporangiate ferns or in Equisetum. 
The sporangia in both Lycopodium and Selaginella 
are borne singly, either upon the inner face of the 
leaves, or upon the axis just above a leaf. They are 
kidney-shaped capsules, which open by a longitudinal 
cleft (Fig. 37, B). The sporophylls are usually 
crowded together into a cone or strobilus, somewhat 
as in Equisetum. In Lycopodium all the sporangia are 
alike, but in Selaginella the oldest one (or ones), at the 
base of the cone, matures but four spores (macrospores), 
which are very much larger than the numerous micro- 
spores produced in the upper sporangia (Fig. 38, B). 
The development of the two kinds of spores is the same 
up to the point where each mother-cell divides into the 
four spores. In the microsporangia all the spores de- 
velop, but in the macrosporangium only one tetrad comes 
to maturity, the others serving simply as food for the 
developing macrospores. These begin to germinate 
within the sporangium, and besides using up the other 
spore-tetrads as food, are nourished from the sporophyte 
through the cells of the sporangium-wall, which re- 
