510 BOTANICAL GAZETTE [JUNE 
water, it sinks by its own weight, thus forming the flatter, lower, and 
more compact part just back from the edge. Willow thicket is 
invading the moor in many places. It is replaced by meadow scrub. 
At several points sedge moor passes directly into sedge moor, thus 
omitting the thicket and scrub stages of succession. 
The principal species in the sedge moor of Boulder Park is 
Carex variabilis. It is a peat forming species. In reaction, the 
soil of the sedge moor is very slightly acid. The plants of the asso- 
ciation stand close together. There is always an abundance of 
moss, which is of great importance in the building of peat. The 
sedge moor becomes marshy during the spring and early summer 
and after heavy rains. Then, the water aids in the packing down 
of dead sedge plants. The water table is always high and the soil 
water content high throughout the year. Stratification occurs 
to some extent. The following species form a ground layer: 
Androsace subumbellata (A. Nels.) Small, Galium trifidum L., 
Crunocallis chamissonis (Esch.) Greene, Veronica serpyllifolia L., 
Alsine longifolia (Muhl.) Brit., moss, and liverworts. Caltha 
rotundifolia (Huth.) Greene is an important component of the sedge 
moor. It is not a shade plant and hence does not do as well in the 
denser parts of the association as in more open spots. 
Petasiies sagittata Gray is prevernal in the sedge moor. Caliha 
is the characteristic species of the spring aspect (May 15~July 1). 
The summer aspect (July 1-August 15) is marked by a large num- 
ber of sedges, grasses, and other herbs, most important of which are 
Carex variabilis, Deschampsia caespitosa (L.) Beauv., Hierochloa 
odorata (L.) R. and S., Sedum rhodanthum Gray, Pedicularis groen- 
landica Retz., and Agrostis hiemalis (Walt.) B.S.P. The appear- 
ance of gentians the latter part of August ushers in the autumn 
aspect (August 15—October 1). Chief of these are Pleurogyne 
fontana A. Nels. and Gentiana plebeya Cham. During the winter 
the sedge moor is a level expanse of withered shoots and leaves, 
chiefly Carex. 
As compared with drier associations, the seasonal aspects of 
the sedge moor change slowly. The reason for this is partly the 
fact that Carex hides other forms growing within it, and furthermore 
to the actual paucity of species in this area as compared with drier 
