94 LVOLUTION OF Life 
RHIZOCARPE, 
The Rhizocarpz, a group of minute water-plants, are 
represented by four genera found in different parts of the 
world, of which: the Pillwort and Pepperwort are probably 
the best-known, these plants being rather botanical curiosi- 
ties than objects of every-day attention. They are incon- 
Spicuous plants, growing in the mud at the edges of pools, 
or floating about in stagnant water, A plant of this group 
(Marsilea) (Fig. 127) consists of a creeping stem; from the 
upper side rise stalks ending in leaves, from the lower hang 
roots; at the base of the stalks, near the roots, are seen the 
spore-cases (sporocarps): hence the name of this order, 
Rhizos- (root) carpe (fruit). The spore-cases of the Pill- 
wort (Pilularia) and Pepperwort (Marsilea) contain both 
small and large spores. In Salvinia and Azolla the large 
and small spores have each their special spore-case. The 
importance of this arrangement of the reproductive appa- 
ratus in Salvinia and Azolla will appear when speaking 
of the flowering plants. The development of the future 
Rhizocarp from the large and small spores is the same as 
that observed in the Club-mosses, to which we will now turn. 
LYCOPODIACEZE. 
The Lycopodiacez (Fig. 128),or Club-mosses, are delicate 
creeping plants, producing leafy-like branches, resembling 
in their general appearance Mosses, though differing from 
them in structure and manner of reproduction. The Club- 
mosses of the present day are small plants; this was not 
always the case, the order being represented in past time 
by trees, attaining the height of sixty feet, with gigantic 
roots, giving the vegetation of that period a very charac- 
teristic appearance. The stem of the Lycopodiacez exhibits 
the same vascular and cellular structure noticed in the 
