CALIFORNIA PLANTS IN THEIR HOMES 



others become themselves small trees. Geologists tell us 

 that ages and ages ago the earth must have been very 

 densely covered with ferns and kindred plants, much larger 

 than those we know to-day. Our principal coal fields have 

 been formed by these plants, so we may sit by our firesides 

 and enjoy the sunbeams imprisoned by ferns and their 

 relatives countless years ago. 



Fig. 30. 



1, 2, 3. Spore-cases of ferns, x 75. 4, 5, 6. 7. Early stages of maiden-hair ferns. 

 8. Fern prothallium, magnified and diagramatic. 9, 10. liverworts. 



