224 BOTANICAL GAZETTE [MARCH 
moderate shade, the last named shrub (white-flowered raspberry) 
often forms a dense tall thicket growth beneath them. There is 
also a characteristic group of herbs that follow close upon the decline 
of the fireweeds. These are Castilleja pallida (L.) Spreng. var. 
septentrionalis (Lindl.) Gray, Lilium philadelphicum L., Pleris 
aquilina L., and others in the early stages; and Aster macrophyllus 
L., very abundant in the mature burn forest. A forest mainly of 
birches in clumps, with undergrowth as described above, is prac- 
tically certain indication that fire has recently visited the area. 
Fic. 53.—A group of birch stump sprouts in an area that was burned about 35 
years ago: the original trunk is shown; near Park Place Hotel 
Frequently neighboring burns of different ages are indicated by 
patches of birch forest of differing height. 
None of the areas of burn forest of historic age upon Isle Royale 
are old enough to show the late stages in the transition to the 
climax. The process is indicated, however, by the frequent 
occurrence of young spruce and balsam under the light shade ol 
the birches. Occasional conifers germinate immediately after the 
fire, but the thorough occupation of the ground by the fireweeds 
and the rapid growth of the birch sprouts, as well as the dryness 01 
the ground, prevent them from starting in abundance. The devel- 
