Transcription of video clip Trunk layers

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© Jardin botanique de Montréal
Outer bark, secondary phloem, and cambium

The outer bark is the first trunk layer, the one we see.

The inner bark, in red, is called secondary phloem. The phloem transports sugars throughout the tree.

Following is the cambium, a very thin row of living cells.

It is from the cambium, in green, that each trunk layer is constructed.

© Jardin botanique de Montréal
Sapwood and heartwood

Then there’s sapwood, which transports water from the roots to the leaves.

Finally, deep inside the trunk, lies the heartwood, acting as structural support.