As the name implies, these forests are dominated by hardwoods that shed their leaves in the fall. Derived items include construction materials, furniture, paper, fuel, and synthetic materials based on cellulose, e.g., rayon and cellophane. In general, angiosperm wood denser than gymnosperm wood, as a reflection of the increased amount of lignin. Rings of secondary xylem develop each growing season. In contrast, the superficial, conductive sapwood is usually wet.
Woods demonstrate different grains .
Knots are the bases of branches covered over by subsequent lateral growth of the tree trunk. USA and Canada are leading lumber-producing countries. Pine is often used in house construction, as it is light but strong. P. strobus was the most important timber tree in US until 1900s, when white pine blister rust introduced. In the US, oaks are the most economically important hardwoods.