442 PHARMACEUTICAL BOTANY 
One of these fertilizes the ovum forming an odspore (zygote). 
The odspore begins to divide and ere long develops into an 
embryo which soon becomes differentiated into foot and shoot 
regions. ‘The foot absorbs nourishment from the prothallus, for 
a short time, until the first root commences to function. The 
shoot elongates carrying ‘the first leaves above the soil and giving 
rise to the first root or radicle at its base. Through continued 
growth and differentiation a mature sporophyte is developed which 
consists of a creeping, prostrate, dichotomously branching stem 
covered with crowded, light green, linear, awl-shaped, and 
_bristle-tipped leaves and bearing several ascending fertile. 
branches which terminate in one or two spikes. Each of these 
spikes consists of a slender axis bearing numerous more or less 
deltoid, bristle-tipped scales, each one having a kidney-shaped 
sporangium at the base of its upper surface containing numerous 
Spores. 
FamiLy II.—SE.LaGINELLACEZ# (Little Club Mosses), includ- 
ing the single genus Se/aginella with species for the greater part 
tropical. Plants similar in habit to the Lycopodiacee but produc- 
ing microspores and megaspores, hence showing heterospory. 
The microspores are formed in microsporangia which are borne 
all 
for ornament. One of them, Selaginella lepidophylla, a native of 
Mexico, is a “resurrection plant,” curling up if allowed to dry 
and, when apparently dead, capable of being revived in water. 
Famity III.—Isorracra (Quillworts) including the single 
genus Isoetes whose species are plants with short and tuberous 
stems giving rise to a tuft of branching roots below and a thick 
rosette of long, stiff, awl-shaped leaves above. They produce 
microspores and megaspores and so show heterospory. 
