
1901 | GENETIC DEVELOPMENT OF FORESTS ii te 
including young plants of beech and maple, are excluded 
because the insolation is great. Some few plants that seem to pre- 
fer more xerophytic conditions likewise will not thrive. Then the 
struggle is nar- 
rowed to those 
plants that can 
endure strong in- 
solation, that pre- 
fer tolerably 
good edaphic 
conditions, and 
whose seeds are 
present. It is ob- 
vious that those 
plants in the 
neighborhood 
that have the 
lightest seeds will 
have the largest 
representation of 
seeds on the 
ground first, and 
of these the most 
rapid growerswill 
prevail the first 
year ortwo. The 
so-called ‘fire- 
weeds’’ meet 
the requirements 
best. Epilobium 
angustifolium,Eri- 
geron Canadensis, 
and certain gold- 

Fic. 12.—A hemlock-maple forest bordering onan 
arbor vitae swamp. The tangled growth of the arbor vitae 
seen in the nagar The hemlocks ,are 
Swamp is 
encroaching on the arbor vita 
enrods spring at once into an occupancy of ‘the field. and there 
is given a “ fire-weed ” physiognomy to the clearing ( fig. 14). 
The poplars (P. tremuloides and P. grandidentata) and the 
