208 
GOTE TURESSON 
by the flora that occupies the bottom of the skunk cabbage pits. 
The nature of the flora which finds shelter here will become clear 
from the following list of plants found in six different pits. 
I. Angelica genuflexa, Limnorchis leucostachys robusta, Viola palustris. 
II. Angelica, Galium aparine, Trientalis latifolia. 
III. Angelica, Athyrium cyclosoriim, GauUheria shallon, Spiraea 
douglasii. 
IV. Alnus oregona (seedling) Angelica, Athyrium, GauUheria shallon, 
Hieracium scouleri, Lonicera involucrata, Rhamnus purshiana, 
Sambucus callicarpa (seedling). Spiraea douglasii (seedling). 
V. Athyrium, Car ex sp. 
VI. Epilobium adenocaulon, Car ex sp. Potentilla palustris. 
Most of the above mentioned plants do not produce any flowers 
on account of deep shade and crowded conditions in the pits. How- 
ever, seedlings of trees often get a start here and some succeed in 
reaching further development. Many of the trees and shrubs now 
growing in the bog, as for instance Alnus oregona and Cornus occi- 
dentalis, began in all likelihood their development in one of these 
pits. 
The importance of the skunk cabbage pits and their floras in the 
replacement of the xerophytic bog flora by a more mesophytic is 
perhaps greater than it appears to be. There is no doubt, however, 
that partial drainage of the bog also has played its part in bringing 
about the present composition of the vegetation. 
LITERATURE CITED 
1. Atkinson, G. F. A College Text-bock of Botany. Henry Holt and Co. 
New York. 1905. 
2. Blytt, A. Essay on the Immigration of the Norwegian Flora during Alternating 
Rainy and Dry Periods. Christiania. 1876. 
3. Burns, G. P. A Botanical Survey of the Huron River Valley. VHI. Edaphic 
Conditions in Peat Bogs of Southern Michigan. Bot. Gaz. 52: 105-125. 
1911. 
4. Cooper, W. S. The Climax Forest of Isle Royale, Lake Superior, and its develop- 
ment. Bot, Gaz. 55: 1-44, 1 15-140, 189-235. 1913. 
5. Cooper, W. S. The Ecological Succession of Mosses, as Illustrated upon Isle 
Royale, Lake Superior. PI. World 15: 197-213. 1912. 
6. Cowles, H. C. The Physiographic Ecology of Chicago and Vicinity. A Study 
of the Origin, Development and Classification of Plant Societies. Bot. Gaz. 
31: 73-108, 145-182. 1901. 
