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FRANK C. GATES 
angustifolium, and Erigeron ramosus. Overtopping all other vegeta- 
tion are a few scattered giant trees of Pinus strohus and Pinus resinosa. 
Fig. 2. Diagram showing the daily rate of evaporation in cc. and the pre- 
cipitation in cm. for the intervals between readings from certain stations in the 
hardwood series, 191 5. 
The principal trees in the hardwood or beech-maple association 
are Fagus grandifolia, Acer saccharum, Tsuga canadensis, Betula lutea, 
and Tilia americana. Shrubs occur largely in openings, Acer penn- 
sylvanicum being most abundant. A large number of herbaceous 
species grow near the ground. Among the more frequent of these 
are Aralia nudicaulis, Maianthemum canadense, Trillium grandiflorum, 
Trientalis americana, Aster macrophylhcs, Streptopus longipes, Strep- 
topus roseus, Medeola virginiana, Clintonia horealis, and Actaea alba. 
Clearings made in different years, now covered with mixtures of 
vegetation, furnish series from bare ground up to the hardwood as- 
sociation. Another series leads from bare ground, through aspens, to 
