SUMMARY 375 



favored the growth of fern plants. Where these large 



ferns died and fell to the ground, great masses accumulated. 



As the earth's surface changed, these masses became 



covered with soil or water, and under tin- influence "i' 

 heat and pressure they changed into coal. At tin- Bame 

 time natural <_ r as and petroleum, or rock oil, were formed. 

 No coal is being formed at the present time, and when our 



present supply is exhausted, we shall have t<> find other 

 sources of heat and power. 



SUMMARY 



Ferns and their allies are less dependent on water than 

 are the alg;e, fungi, and mosses. They are more highly 

 organized, as they have epidermis, stomata, mechanical 

 tissue, conductive tissue, stem, roots, and Leaves. Their 

 life history shows the alternation of generations, consisting 

 of spore, protonema, prothallium, and sporophyte. Club 

 mosses, horsetail, and selaginella are closely related forms. 

 Coal was formed when ferns grew to the size of trees in 

 regions which were then hot and moist. 



QUESTIONS 



What parts of the flowering plant are found in the fern '.' In an animal 

 what corresponds to epidermal tissue? to conductive tissue ? to funda- 

 mental tissue? to mechanical tissue? Compare the life history of a 

 moss and a fern. Why can ferns do with less water than mose Illus- 



trate by diagrams or sketches the life history <>t" a fern. What plants 

 related to ferns ? Tell how coal beds were formed. 



REFERENCES 



Bergen, Foundations of Botany. Bryophytes, page 277, Pteridophj 

 page 286. 



Campbell, A University Textbook of Botany, Bryophytes, pa 

 Pteridophytes, page -11. 



Curtis, A Textbook of General Botany, Chapters VII and VIII. 



Leavitt, Outlines of Botany. Bryophytes, page 108, Pteridophytes, | 

 204. 



