LORS Ee 
November, 1912. 
Vol. 12 No. 11 
THE RELATION OF SNOW COVER TO WINTER 
KILLING IN CHAMAEDAPHNE CALYCULATA* 
Bv FRANK C. GATES 
During the course of a piece of investigation at the University 
of Michigan during 1910—1912, some interesting observations 
and measurements were made upon Chamaedaphne calyculata, 
a heath plant which grows in the peat bogs of the vicinity. 
The winter of 1910-11 was normal for southern Michigan. No 
extremely low temperatures were recorded and the snow, al- 
though above the average during the early part of the winter, 
was below it during the coldest weather, so that at the time 
of severest cold (— 20? C.) the bushes of Chamaedaphne were 
less than half protected. The cold spells were of short duration, 
however. 
The winter of 1911-12 was extreme both in amount and dura- 
tion of cold and of snow. New records were set both for the 
absolute minimum and for the duration of severe cold. 
Before entering into the main subject a brief account of the 
vegetational history of Chamaedaphne wil be advantageous. 
During the early part of a growing season the shoots of the year 
develop large (2-4 cm. long) leaves. Towards the end of the 
growing period small leaves, in whose axils are flower buds, are 
produced. Both large and small leaves remain on the bush 
over winter. With approaching winter the green color of the 
leaves is replaced by a dark reddish brown, the petioles become 
red, and the leaves bend up into an upright position. With the 
* Contribution from the Botanical Laboratories of the University of Michigan, 
No. 135. Spelling changed from the form recommended by the Simplified Spelling 
Board, to conform to the usual procedure in TORREYA.—ED. 
[No. то, Vol. 12, of TORREYA, comprising pp. 229-256, was issued 4 October 1912.] 
