PLANTS WITHOUT SEEDS 
23 
The first land plants were the liverworts. 
These are like the algae except that they de¬ 
veloped roots and thicker cell walls to keep the 
water from drying out. The liverworts could 
live on land, but it had to be moist. They 
could not stand more than a short dry spell. 
The mosses seem to have come next after the 
liverworts, for although they grow in moist 
places, they are able to stand short periods of 
dry weather fairly well. 
Mosses grow close together. The clusters of 
plants soak up water and hold it like a sponge. 
That is one way in which they provide against 
drying out. All parts of the plant, however, 
must be near to the water, for there is no system 
of tubes to carry the moisture from the roots to 
the leaves. The absence of tubes shows that the 
mosses came early in the history of plants. 
Mosses sometimes send up little shoots that 
look like flowers. They are not flowers, al¬ 
though we might call them the great grand¬ 
mothers of flowers, and they do not produce 
