Thoreau writes in his journal:
The black spruce, is the prevailing tree, commonly six or eight feet high, but very few, and those only in the most sheltered places, as hollows and swamps, are of regular outline, on account of the strong and cold winds with which they have to contend . . . So stout and tapering do they grow . They spread so close to the rocks that the lower branches are often half worn away for a foot in length by their rubbing on the rocks in the wind, and I sometimes mistook the creaking of such a limb for the note of a bird . . .