YI. 



HOW COLD AFFECTS PLANTS.* 



If one should carefully note the exit of his 

 floral acquaintances in the autumn he would 

 find that not all of them succumb to the rigors 

 of the cold season at the same time. Some 

 of the members of the plant communities pe- 

 culiar to meadows, woods and slopes will 

 give over activity at the first suggestion of 

 frost, while others endure a long succession 

 of freezing nights before they finally perish. 



Still others, the conifers and evergreens, the 

 thick beds of mosses, and the thin green layers 

 formed by the liverworts and the grayish 

 coating formed by the lichens, live through 

 arctic winters without great apparent change, 

 except indeed that some grow and fruit in and 

 under the snow. Between the groups which 



*GiYen before the Botanical Seminar, University of Minne- 

 sota, Nov. 13th, 1897. 



