508 



INTRODUCTION TO CEYPTOGAMIC BOTANY. 



or invested by a distinct cover (indusium), springing mostly 

 from a vein, but sometimes extending to the neighbouring 

 parenchym ; rhizoma creeping or after a time erect and sub- 

 globose, or cylindrical and arboreous, sometimes climbing. 



570. No plants are more easily recognised than Ferns, not- 

 withstanding the multitudinous forms under which their fronds 

 appear, and their diversity of growth. The circinate aestiva- 

 tion and hypophyllous fruit, added to the peculiar habit and 

 venation, at once establish their nature. Stangeria (Fig. 1) 

 has, indeed, the same venation and aestivation, but the strobili- 



Fig. 110. 



a. HymenopJiyllum Lyalli, natural size. From a New Zealand 

 specimen. 



b. Two pinnss of Oleichonia microphyUa, the tip of one of wMeli is 

 expanded by a hot moist atmosphere. 



c. Young leaves from bulbs of Marattia alata, to show the large foli- 

 aceous processes of the base of the stipe. Magnified. 



d. Horizontal section of cysts of Olearia hirta, magnified. 



e. Ends of ditto. The three last fi'om Kew. 



/. Cysts from a tree-fern from Guatemala, magnified. 



