Why is wood so strong and useful for building, even though it comes from a living tree?
Wood is mostly xylem.
Wood is mostly xylem. Its water-conducting cells have thick walls reinforced with lignin, and once mature these cells die, leaving hollow, rigid tubes. This dead, lignified tissue is exactly what gives wood its strength and rigidity while still being light — perfect for furniture and construction. The inner heartwood, fully dead, is the strongest supporting part of the trunk.
Key point
Wood is dead, lignin-thickened xylem, which makes it strong, rigid and light.
Common mistake
thinking the useful wood is made of living cells.
Memory tip
lignified dead xylem = strong wood; heartwood is the toughest core.
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