RELATIVES OF THE FERNS 6i 



summer weather the Azolla grows very rapidly 

 in this country, so that even the native 

 water plants are occasionally overwhelmed by 

 its activities. Sometimes the surface of the 

 pond is completely covered in with the foliage. 

 Underneath the floating leaves there is a large 

 quantity of roots which hang downwards into 

 the water. The plant produces two kinds of 

 spores, those known as megaspores being pro- 

 vided with a floating apparatus and singular 

 hook-like contrivance. The microspores, which 

 are ejected from the spore cases in packages, 

 have certain barbed attachments to which 

 the hooks of the megaspores readily adhere. 

 Thus the formation of the two kinds of pro- 

 thalli which takes place in the water will 

 be soon followed by the blending of the sex 

 elements. 



The Pill Wort {Pilularia globulifera) is an 

 allied species which grows on the mud bottom 

 of ponds or, on occasion, in swampy situations. 

 This is a singular plant, with needle-like leaves. 

 The spores are produced in cases at the base 

 of narrow leaves. These spore cases are rather 

 comphcated as a matter of fact, in that they 

 are divided into several compartments, in which 



