Compléter Wood 1Version en ligne Wood as a technical material (I) par Fernando Martínez 1 hardwoods centre softwoods heartwood Hardwoods evergreen hardens harder ring sapwood material annual natural heavy strength manufacturing Heartwood deciduous builders bark Softwoods Wood is a that has been used for many centuries by and craftspeople . There are two basic types of wood : hardwood and softwood . are generally than and come from trees . come from trees . They are not usually as as . Each year a new layer of growth is added just below the , producing an . New growth is called . New layers grow on the outside and the centre to form . is found at the of a tree and is the best part of a tree to use for , because of its hardness and .