Cork is derived from Quercus suber , which produces layers several inches thick. This plant is adapted to a fire-climax environment and the cork provides insulation. It consists of air-filled cells which can be compressed ut to 10,000 lbs per square inch without rupturing. These cells also give cork its buoyant properties. A tree must be about 25 years old before cork can be harvested, and the first year's harvest is poor and usually ground for composition cork.
Later harvests are superior.
These terms refer to the plants that made the wood, NOT to the characters of the wood. Rays are present in both types of wood. Resin canals can occur in xylem, phloem, or bark of either type, but are more common to softwoods. Gymnosperms produce softwood . The xylem consists only of tracheids , which are long cells that conduct water through openings in the side walls.