REPRODUCTION BY LAYERING AMONG CONIFERS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 149 
WILLIAM S. COOPER 
(WITH ONE FIGURE) 
Many types of plants multiply more or less by layering, or may 
be made to do so by artificial means. The fact seems not to be 
well known that various conifers, particularly members of the genera 
Picea and Abies, possess this power and multiply by it to some 
extent. Having by accident discovered a case of layering in the 
balsam fir (Abies balsamea [L.] Mill.) during the course of ecological 
work on Isle Royale, Lake Superior, I found that the habit was a 
factor of considerable importance in the dynamics of the forest. 
Investigation into the literature of the subject brought to light 
a few scattered references to layering of coniferous trees, which 
are noted below. It is not probable that the list is exhaustive. 
I. Literature 
The earliest description that was found was contained in Lov- 
DON’S Arboretum et Fruticetum Britannicum (8), vol. IV, pp. 2297- 
2298. The author quotes Mr. James M’Naps in The Gardener's 
Magazine as follows: 
_ From the pendent habit of the lower branches of the spruce (Picea excelsa 
Link) some curious anomalies are occasionally found in its habit of growth. 
The shoots next the ground, when they have attained a considerable length, 
naturally rest on the soil at their extremities; and the soil being kept moist by 
the shade of the branches, these often root into it; and the points of their 
shoots taking a vertical direction, a series of new trees are formed in a circle 
round the old tree. 
A particular specimen, growing in Scotland, is described thus: 
Many natural layers from the trunk and from the primary substems 
have taken root, so as to form a double series of young trees in two concentric 
circles round the parent trunk. 
A little farther on is the following: 
That portion of the branch which is between the trunk of the original 
tree and the part where it roots into the ground, and which is sometimes several 
feet in length, rarely i in diameter after its extremity has rooted... . . 
369] [Botanical Gazette, vol. 52 
