1913] COOPER—ISLE ROYALE 217 
Among the delta swamps studied, the largest was at the head 
of McCargoe’s Cove. The alluvial flat was here 0.8 km. long by 
o.4km. wide. All the stages are here well developed except the 
swamp forest, which has been fire-swept. Part of the meadow-like 
marsh is shown in fig. 49, and a sketch map of the delta is given in 
g. 50. Farthest out, in water a meter and more deep, is a zone 
of Potamogeton perfoliatus L. Within this, in a few inches of water, 
grows Equisetum fluviatile L. Next comes the sedge mat, firmly 
grounded, with Carex filiformis as the principal species, accompanied 
chwewiiepe 
Fic. 49.—Delta swamp at the head of McCargoe’s Cove: sedge, grass, and shrub 
ielekien w are shown; the swamp forest has been burned. 
by bog herbs. The area dominated by Calamagrostis is the most 
extensive, and its level is perceptibly higher than that of the sedge 
zone. With Calamagrostis grow other herbaceous species, many of 
them tall, such as Thalictrum dasycarpum Fisch. and Lall. (tall 
meadow rue), Chelone glabra L. (turtle-head), Epilobium angusti- 
folium L. (fireweed), and Symplocarpus foetidus (L.) Nutt. (skunk 
cabbage). Stools and patches of Calamagrostis were seen as in- 
vaders of the sedge society, and occasional shrubs, pioneers of the 
next group, were scattered over the area occupied by the grass. 
Myrica Gale L. (sweet gale) is the first shrub to invade the 
