32 MISSOURI BOTANICAL GARDEN. 



region a sewage pipe enters. Here Oscillatoria is dominant. 

 The floor of this stream is smooth and muddy. The surface 

 of the water is never frozen in winter. It varies in volume 

 with precipitation and becomes very turbid at these times. 

 Cladophora canaliculars during the winter was covered 

 with diatoms which as the spring advanced diminished until 

 by the first of May they had disappeared. The plants looked 

 ragged and unhealthy at this time, but soon began to branch 

 and regain their bright green color. On the stones near 

 Cladophora, Stigeoclonium glomerata suddenly appeared in 

 the spring and within a month disappeared. In the east end 

 of the stream where the water was sluggish the Blue Greens 

 were the principal forms. On the mud at the edge of the 

 water in this region, a small form of Vaucheria grew, — a 



3rent species from the one in the Arboreti 

 dominant forms were present during the 



Here 



study. 



boretum pond 



This is a small crescent shaped body of 

 water from a few inches to two feet deep. It has no outlet so 

 that the water is stagnant. It contains much decaying as 

 well as living vegetation, consisting of Typha, J uncus, Iris, 

 Acorus and Nymphaea, which makes conditions favorable for 

 a rich growth in algal forms. This pond freezes earlier and 

 remains frozen longer than the Fountain pond. 



body of water has more characteristic forms 



other. 



v, 



water. Here Vaucheria forms a thick mat with sev< 

 teriums (see list) Oscillatforias and a Lyngbya scattered 

 among its filaments. In the center and east wing in deeper 

 water the other algae were attached to the stems of Acorus 

 or Nymphaea or floating in a tangle of decaying vegetation. 

 Oedogonium was very rare here, though common in the 

 habitats which had Cladophora. Tetraspora w T as first attached 

 then floating over the whole water surface. Scenedesmaceae 

 were practically absent. Chaetophoraceae are predominant. 

 This is the only location in which Ulothricaceae were found. 

 Nelumbium pools. These are two cement basins with no 



outlet. The water is 2-3 in. deep. They are covered in win- 



