50 



EASY LESSONS IN VEGETABLE BIOLOGY. 



OHAPTEE IX. 



ACROGIENS, OE PLANTS WHICH G&OW AT THE SUMMIT. 



1. IN fresh-water ponds and rivers, growing in 

 tangled masses of a dull green color, we may often 



Fig. 20. 



find plants with stems about as thick as a stout needle, 

 but perhaps three or four feet long, with branchlets 

 (improperly called leaves) arranged in whorls at regu- 

 lar intervals upon the axis. These are the stone-worts, 



