14Y 



the predominant form, here growing very dense and close. There are also 

 dense strips of considerable length on the shore along the northern end of 

 the lake. Its distritnition seems to be determined by the presence of solid 

 sand-beds or liars wliore it deliglits to grow. It generally grows wholly 

 on shore or in oidy qnite shallow water, and does not seem to lil^e the 

 beating of waves so well as does N. Idciistris. Fig. 3 shows a characteristic 

 set of relations isonth of Chicago Hill picri. ^^'illows on ice ridge at the 

 left. tSciriHis (iiik ricinnis on sandy liaiii';. N. hicitstris in water with stiMns 

 on shore. A patcli of ronUdcrhi inrdutn in water in foreground. 



Fig. .3. 



POXTEDERIA CORD AT A occurs in small or isolated patches all around 

 the lake, but by far the largest and most continuous stretch is at the south 

 end. not a great way from the mouth of Clear Creek. This plant is gener- 

 ally associated with KympJiaea adrcua and is closely similar to it in 

 structure and habit. It generally foi*ms a belt between the main mass of 

 NijmpMeo and the shore. The Pontedcria farthest from shore grows in 

 among the Nijniphaea nearest the water's edge. Sagittaria, in so far as it 

 grows along the shore, occupies nearly the same position, except tliat it 

 grows at the water's edge. Poiitcdn-id and Xmnphned grow in considerable 

 abundance in the pond soutli of tlie lake, and Smjitttiriit I'as its best de- 



