1913] FULLER—LAYERING IN BLACK SPRUCE 453 
granite hills with typical roches moutonnées contours and with eleva- 
tions varying from 100 to 200 meters, in Chicoutimi County, border- 
ing an arm of the river known as Ha! Ha! Bay. In these exposed 
situations there occurred a characteristic pioneer forest association 
consisting, as far as its tree species were concerned, of black spruce 
(Picea mariana Mill. BSP.), Jack pine (Pinus Banksiana Lamb.), 
the white birch (Betula alba papyrifera (March.) Spach.), and the 
aspen (Populus tremuloides Michx.), together with occasional trees 
Fic. 2.—The prostrate branches of the black spruce rooting in the mat of mosses 
and lichens and producing upright shoots; one such shoot has been provided with 
a white background. 
of a few other species. Because of the slow weathering of these 
areas, the pioneer stages of forestation were much prolonged, but 
appeared to be promoted by the development of a peculiar growth 
habit and a resulting vegetative reproduction by layering. This 
habit was most highly developed and occurred most frequently in 
the black spruce. 
Grown in swamps or thickets the black spruce is characterized 
by a narrow irregular cone of branches. This cone was found to be 
