THE CLUB-—MOSSES 547 
Fic. 376.—Martin’s Selaginella (Selaginella Martensii, Selaginella Family, 
Selaginellacee). Germination of macrospore (98), cut vertically, 
showing the female gametophyte protruding from the ruptured spore- 
wall (spm) and exposing an unfertilized archegonium (ar), but still 
enclosing two embryos (emb!, emb2) which have been pushed down into 
the nutritive prothallus (pr) by their suspensors (et, et). (Pfeffer.)— 
Native home, Mexico; much cultivated. 
Fic. 377.—Martin’s Selaginella. Embryo (+32), cut vertically to show its 
suspensor (et), root (w), leaves (bl, bl), ligules (lig, lig), and tip of stem 
(st). (Pfeffer.) 
projection (lig) termed a ligule,! arises, which, by secreting mucilage, 
serves to keep the tender terminal organs from drying. 
The formation of macrospores that begin to germinate while 
still within the sporangium, marks a most important advance in the 
care of offspring; for by this means not only are the chances of cross- 
fertilization increased, but the embryo is afforded more protection, 
and the young plantlet can be provided with a larger quantity of 
promptly available food while preparing for independent life. Just 
one step further is needed as we shall see, to attain the high develop- 
ment of parental care achieved by seed-plants. A similar differen- 
tiation of the spores and sporangia into male and female is found 
also in certain types of Filicine, and in extinct Equisetine. 
As with scouring-rushes and ferns, so with the club-moss 
class, the modern species but feebly represent their kin of 
the coal age. These include giant lycopods such as Lepido- 
dendron (Fig. 278, page 301) and Sigillaria (Fig. 277, page 299) 
with much-branched trunks ten meters or more in height and 
often a meter in thickness, bearing cones as large as those 
of a pine tree, and forming extensive forests. 
1 Lig’ule < L. ligula, a little tongue. 
