LIFE HISTORY OF A FEEN 



have died and fallen away. The rhizome bears true roots 

 (Fig. 2), and its tissues are differentiated into epider- 

 mal, fundamental, mechanical, and conducting systems 

 (Fig. 3). In tropical countries there are "tree ferns," 



FiQ. 6. — Osmimda Clayt-oniana. Young sporophylls, showing circinate 

 vernation. Note the spore-bearing pinna;. 



with upright stems, and this type of fern is common 

 among the fossil plants of earlier geological ages (Fig. 4). 

 There are also climbing ferns. 



3. Two Kinds of Fern-leaves. — Careful examination 

 of the leaves of certain mature ferns will disclose the fact 



