Sentence:  Thus the Birch Canoe was builded / In the valley, by the river, / In the bosom of the forest; / And the forest's life was in it, / All its mystery and its magic, / All the lightness of the birch-tree, / All the toughness of the cedar, / All the <WSD>larch</WSD>'s supple sinews; 
Meaning of the word marked with <WSD> tags:  A coniferous tree, of genus "Larix", having deciduous leaves, in fascicles.