In species which show a distinct difference between <answer>heartwood</answer> and sapwood the natural color of <answer>heartwood</answer> is usually darker than that of the sapwood, and very frequently the contrast is conspicuous (see section of yew log above). This is produced by deposits in the <answer>heartwood</answer> of chemical substances, so that a dramatic color difference does not mean a dramatic difference in the mechanical properties of <answer>heartwood</answer> and sapwood, although there may be a dramatic chemical difference.
When trees have a visible difference in color between sapwood and heartwood, which is darker?
heartwood