Induced Changes in Reserve Materials in Evergreen 
Herbaceous Leaves. 
BY 
GWYNETHE M. TUTTLE, M.Sc., 
Botanical Department, University of Alberta. 
With seven Figures in the Text. 
E VERGREEN trees are generally divided into two classes: (a) ‘starch * 
trees, whose reserve food is stored in the form of starch, and (b) ‘ fat ’ 
trees, in which the starch is converted into oil during the autumn. According 
to Warming (1), the presence of oils and fats in the latter may enable the 
plant to withstand lower temperatures, ‘ in that fatty oil in the form of an 
emulsion prevents the sub-cooling of the plant tissue and increases the 
power of resistance to frost ’. Hence we find this class of trees largely 
distributed throughout the colder regions, while the ‘starch’ trees are found 
in localities of higher winter temperature. 
Much attention has been given to this phenomenon in trees, but no infor- 
mation is available in connexion with herbaceous plants. Since many 
evergreen herbaceous plants grow in the shade of the ‘ fat ’ trees subjected 
to the same extremes of cold, it would seem possible that they should 
exhibit similar features. It was with a view to ascertaining a few facts in 
this connexion that the present work was undertaken. My attention was 
called to the need for investigation in this direction by Dr. F. J. Lewis, to 
whom I am greatly indebted for helpful criticism and suggestions given 
throughout the progress of the work. 
The only recent investigation bearing on this subject is that of Kiichi 
Miyake (2) at Tokyo. He confined his attention solely to the calculation 
of the winter starch content of a number of trees and herbaceous plants 
from different parts of Japan. The conclusion is reached that the starch 
content of trees in winter is very small compared with that during the 
summer, but that the content varied with trees of different species and also 
with the region from which the material came — that from Northern Japan, 
[Annals of Botany, Vol. XXXIII. No. CXXX. April, 1919.] 
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