ECOLOGICAL STUDY OP BRUSH LAKE. 1 57 



side the wide, shallow, artificial area of water corresponding to 

 this zone is mostly covered with Chara sp., various pond weeds, 

 Batrachium divaricatum (Schr.) Wimm., and Zannichellia 

 palustris L. 



An interesting plant also is Cicuta bulbifera L., which is 

 covered in the fall* with little bulbs. These drop off and float 

 around on the surface of the water. Although found in several 

 places this plant does not seem able to hold much ground consid- 

 ering the great advantage it has of being distributed into every 

 favorable nook and corner by means of its brood buds. Eleocharis 

 palustris (L.) R. & S. and Scirpus lacustris E. are also promi- 

 nent in this zone. The floating plants of the water-lily zone are 

 abundant, as would be expected. Other plants which are present 

 are as follows : 



Roripa palustris (L.) Bess. 

 Naumbergia thyrsiflora (L.) Duby. 

 Scutellaria lateriflora L,. 

 Bidens cernua L. 

 Polygonum punctatum Ell. 

 Alisma planlago L. 

 Sagittaria latifolia Willd. 



4. Decodon Zone. This is one of the most remarkable 

 societies surrounding the lake. It is a Decodon-Solanum dul- 

 camara zone. The characteristic plant, which in many places 

 forms almost a pure society, is the tall crownformer, Decodon 

 verticillatus (L,.) Ell. The twining bittersweet, Solatium dul- 

 camara L,., is also very prominent. Some of these plants develop 

 as floating individuals, having no connection with the ground, 

 but developing numerous water roots along the submerged part 

 of the stem. This zone is 30 feet wide at the north end. It 

 begins in water from one to one-half foot deep and ends at the 

 outer edge in water of about three or four inches, or even beyond 

 the water's edge. At the north end it is limited on the outside 

 by the shrub zone which extends to the edge of the water or 

 beyond. The tali shoots of the Decodon, man}' of which are 

 fasciated, form a tangled mass through wdiich it is very difficult 

 to pass both when they are green and in winter when dry. The 

 Decodon is especially well adapted for holding air in the cortical 

 layer of the much branded base and is thus well fitted to carry on 



