SECTION VIII. PTERIDOPHYTA (FERNS, 

 EQUISETA, AND LYCOPODS) 



The Pteridophyta, as indicated in the text, are the plants 

 from which the higher plants had their origin in geologic 

 periods earlier than the present era. Their organization and 

 life history are therefore of especial interest in interpreting the 

 structure, ecology, and life history of the higher plants. In 

 order to make clear the contrasts and similarities between the 

 Filicales, or true ferns, and the higher seed plants, the following 

 laboratory directions are written, from the same standpoint and 

 with similar headings and references as the directions on the 

 higher herbaceous and woody plants of Part I. Constant refer- 

 ence is also made to the earlier work of the student, and to 

 the text dealing with the organization and adaptations of higher 

 plants to the environment. 



A. FILICALES 

 SPOROPHYTE 



Select for study one or more species of common wild and 

 cultivated ferns which show both mature and young, growing 

 leaves. Wash the earth carefully from stem and roots of at 

 least one specimen and study as follows : 



1. Plan of the plant body. Compare the general plan of 



the plant body of a fern with that of herbaceous and 



woody plants studied earlier in the course, and with 



such seed plants as may be available for comparison. 



a. Is the central axis, or stem, divided into nodes and 



internodes, with regular points of origin for leaves 



113 



