Tort] COOPER—LAYERING AMONG CONIFERS 371 
He speaks of “horizontal snakelike branches crawling over the 
ground, ascending or erect at the ends,” but does not state, nor do 
his figures show, that these branches take root. 
According to Mayr (9) all deciduous trees and conifers are 
able to produce roots when branches or weak stems are bent down 
and placed in contact with the ground for a time. He mentions 
the following genera as among those that have been observed to 
reproduce by layering: Abies, Picea, Pinus, Larix, Pseudotsuga, 
Chamaecy paris, Cryptomeria. 
Micuta (10) briefly notes the habit, and gives an illustration 
of a spruce (Picea excelsa) surrounded by a circle of young trees 
developed from layered branches. 
VOGTHERR (13) speaks of the habit as occurring frequently, 
though often overlooked, and states that it is commonest in moist 
habitats in northern latitudes and in mountain regions. 
Reproduction by layering among conifers has been reported 
in America, so far as I have been able to discover, in two species 
only, both of the genus Abies. 
SuDWorTH (12) in discussing the reproduction of the alpine 
fir (Abies lasiocarpa [Hook.] Nuttall) says (p. 111): ‘Occasionally 
at high elevations branches lying on ground take root (layer), 
from which, however, reproduction is probably rare.” 
In Silvical Leaflet (4) of the Forest Service, devoted to Abies 
lasiocarpa, is the following paragraph: 
Alpine fir frequently exhibits a tendency to reproduce by layering. The 
lower branches, which are procumbent, become covered with earth, roots are 
Produced, and the branches increase in size and assume an upward curve. It 
is doubtful, however, if the tree ever actually reproduces itself in this manner. 
The tendency becomes more apparent with increasing altitude, the main trunk 
tte shorter, while the layered branches form a saucer-like whorl at its 
ase. 
CLEMENTS (3), speaking of the same species in the Colorado 
mountains, states that “all the young firs examined had started 
by layering from the lower branches of parent trees.” 
Concerning the eastern balsam fir (Abies balsamea [L.] Mill.) 
I have found but one notice of the habit. CarrreNDEN (1) in 
discussing the timberline trees of the White Mountains says: - 
