3.2 : 針葉樹と広葉樹

Most cone-bearing trees have needle-like leaves and are classified as softwoods, and most hardwood trees have broad leaves that are shed on a seasonal basis.

Softwood's microstructure comprises large longitudinal cells known as tracheids and a minor proportion of radial cells called rays.

Construction elements, such as structural frames, sheathing, roofing materials, and exterior siding, use softwoods.

Cell fibers and cavities hold moisture in living or newly cut wood. As drying begins, cavity water evaporates, leaving residual water in fibers, causing the wood to shrink.

The stage at which wood shrinks is called the fiber saturation point. At this stage, most softwoods contain around 30 percent moisture.

Hardwood trees have a higher percentage of rays and two distinct types of longitudinal cells: small-diameter fibers and large-diameter vessels.

Hardwoods are used for furniture, door and window frames, interior trim, and floor installations.

Softwoods, when processed into timber, display a rough, simple grain structure, whereas hardwoods often exhibit finer, intricate grain patterns valued for aesthetics.