115 



above the drainage level at the northeast. The inner zone of vege- 

 tation is characterized by Scirpiis cyperinus, Bleocharis obtiisa, Lud- 

 zngia palustris, Juncus nodosiis, and a few relics of Panicuni virga- 

 tum. Outside this is a regular but narrow zone of Polytrichnm, 

 with Polygala sangninca, Juncus acuminatus, Hypericum gentianoides, 

 and Rhexia virginica. Next is the zone of Solidago graminif olia with 

 its usual associate Aristida Uiberculosa, and, as accessory plants, 

 RheA'ia virginica, Juncus acuminatus, Gerardia purpurea, and Poly- 

 gala sanguinea. Either of these outer zones may be absent for short 

 intervals, but are usually very distinct. 



The second pond, F, was almost diy when visited in August, 1908, 

 and its mucky bottom was about 15 inches (4 dm.) below the water- 

 level in pond B. Its vegetation had been badly destroyed by cattle. 



On the windward slope near B a mat of Polytrichnm is develop- 

 ing in a very shallow, flat depression three feet (9 dm.) above the 

 water-level and one foot (3 dm.) above its nearest neighbors. It is 

 surrounded by a large patch of Hypericum gentianoides extending 

 one to ten feet beyond it. 



From this detailed description it is seen that the vegetation of the 

 foregoing series of depressions of the swamp formation comprises 

 four associations of the following species. 



1. The Solidago association. Solidago graminif olia, Aristida 

 tuberculosa, Bquisetum arvense, Spiraea salicifolia. Car ex sp., Poly- 

 gala sanguinea, Gerardia purpurea, Juncus acuminatus, Rhexia vir- 

 ginica. Accessory or relic species : Stenophyilns capillaris, Lespede/^a 

 capitafa, Andropogon furcatus. Cassia Chamacchrista. 



2. The Salix association. Salix longifolia, Salix nigra, Popnlus 

 deltoides. Accessory or relic species : Panicum virgatum, Scirpus 

 cyperinus, Juncus acuminatus, Ludvigia pahistris. 



3. The Polytrichnm association. PolytricJium juniperinum, Hy- 

 pericum gentianoides, Salix pedicellaris. Aster sp., Lycopus ameri- 

 canus, Hypericum niajus, Viola lanceolata, Rhexia virginica, Spi- 

 ranthcs ccrnua. Accessory or relic species: Polygala sanguinea, Pan- 

 icuni virgatum , Juncus acuminatus, Ludvigia pahistris. 



4. The swamp association. Scirpus cyperinus, Juncus nodosus, 

 Bleocharis obtusa, Ludvigia pahistris. Relic species: Panicuni Z'ir- 

 gatum. 



The Salix and PolytricJium associations occupy parallel positions, 

 but develop under different conditions. The former demands a con- 

 siderable supply of moisture and is restricted to the deeper depres- 

 sions, whereas the latter may develop at almost any level in the blow- 



