31 



One may then expect the red maples and elms to begin to 

 show color on dry uplands, also in similar places the choke- 

 berry (Pyrus arbutifolia), tupelo (Nyssa sylvatica), Vir- 

 ginian creeper (Ampelopsis), and white birch (Betula poi)- 

 ulifolia, Ait.), etc. 



Early in September, before there had been any frost, a 

 southern hillside was brilliant with the crimson foliage of 

 the swamp or red maple. The thermometer rarely registers 

 so low as 32° Fahrenheit in Massachusetts in the first part 

 of this month, but it does occasionally in the latter part. 

 The cause of this premature coloration was obviously the 

 prevailing drought, affecting especially uplands, for it was 

 remarked that an extensive row of the same species in a 

 well watered meadow at the base was perfectly green. 



It was the hot weather and drought, together with the 

 injury sustained from insects, which had also induced the 

 colors in the other species above mentioned, for the same 

 kinds under more favorable conditions as to moisture con- 

 tinued green. That this was a correct view of the matter 

 was proved by numerous observations in different localities ; 

 the trees and shruljs with colored leaves being always in 

 dry situations. 



In the second period the weather conditions are consider- 

 ably different: the fall rains set in, the nights become cool 

 or even chilly, and a hoar frost is likely to occur in the 

 latter part of September. There was a light frost Sept. 20 

 of the present year 1900, the thermometer registering in 

 different localities from 36 to 39'' Fahrenheit. The effects 

 of this frost would hardly have been noticed except by a 

 close observer, for the reason above stated, that several 

 kinds of trees and many shrubs had already assumed autum- 

 nal hues ; some instances however were noted which served 

 to show that the foliage had been subjected to some other 

 influence than drought : Hydrangea Japonica, var. Hortensia 

 which till then was green, became much bronzed and later 

 changed to red ; the yellow leaves on elms, ashes and 



