LIFE HISTORY OF A FERN 151 
and leaf-stalk. There is always a terminal bud at the 
tip of the fern-stem (and of the branches when any oc- 
cur) ; and the leaves are usually attached just back of this 
tip. The stems are commonly (though not always) 
covered by hairs or scales (Fig. 106), and on their older 
portions, at some distance back from the tip, may be seen 
FIG. no. A, Upper epidermis; B, lower epidermis, of the fern, Drynaria 
meyeniana. (Camera lucida drawing.) 
the scars, or the ends of leaf-stalks, left by old leaves that 
have died and fallen away. The rhizome bears true roots 
(Fig. 107), and its tissues are differentiated into epider- 
mal, fundamental, mechanical, and conducting systems 
(Fig. 108). In tropical countries there are "tree ferns," 
with upright stems, and this type of fern is common 
among the fossil plants of earlier geological ages (Fig. 109). 
