April, 1908.] 
The Vegetation of Cedar Point. 
3°7 
Proceeding to the next oldest lagoon on Cedar Point we have 
the Lily Pond just to the west of the highest portion of Ridge 
No. G. The present status of the vegetation around the pond is 
about that termed, for the succession on Presque Isle, stages 
“H” and “I”. About the Lily Pond on Cedar Point the fol¬ 
lowing general vegetational structure appears: 
a. The Potamogeton Formation. 
b. The Castalia-Nymphaea Formation. 
c. The Decodon-Persicaria Formation. 
d. The Cephalanthus-Cornus Thicket Formation. 
e. The Rhus hirta Thicket Formation. 
f. The Ulmus-Acer Forest Formation. 
There should be in the deepest part of the pond a Chara 
Formation, but, for lack of the proper facilities for studying this 
vegetation this point was not determined. In similar ponds on 
Presque Isle there was evidence of a central Chara formation, 
although Pieters found in Lake St. Clair that this formation was 
usuallv scanty or entirely absent on a sandy bottom but present 
on a clay or alluvial bottom. 11 
The Potamogeton Formation. 
This formation has here the following structure: 
Facies: Potamogeton pectinatus, 
Potamogeton natans. 
Principal Species: Utricularia vulgaris. 
Secondary Species: 
Naias flexilis, Vallisneria spiralis, 
Philotria canadensis, Potamogeton sp. 
The Castalia-Nymphaea Formation. 
This formation is perhaps relatively of more importance in 
the vegetational structure here than is the preceding formation: 
Its structure is essentially as follows: 
Facies: Castalia tuberosa, 
Nymphaea advena. 
Secondary Species: 
Potamogeton natans, Philotria canadensis, 
Utricularia vulgaris, Potamogeton sp., 
Scirpus validus, Decodon verticillatus. 
This formation, relatively among its competitors, is a rapid 
soil-former. The plants of the formation typically exhibit large 
rootstocks, which upon their decay contribute considerably to 
the accumulation of humus, while the tangled mass of petioles 
and leaves in and on the water not only catch much floating 
debris, but, upon their decay, also add to the humus beneath. 
11. Pieters, A. J. The Plants of Lake St. Clair. Michigan Fish 
Commission Bull. 2 : 6 and 9. 1894. 
