Explore a tree trunk!
Cork
What we think of when we think of "bark". A dead protective layer that keeps the tree safe from many different threats. Takes many forms: ridged, smooth, flaky, powdered.
Cork cambium
One of the two parts of the trunk that is actually growing. It produces the cork to its outside and the cork skin to its inside.
Cork skin
A live layer that can photosynthesize! Also known as the phelloderm. When a tree trunk looks a little green, it's because the bark is thin enough that the cork skin can still photosynthesize.
Active phloem
One of the two highways of the trunk! Takes the sugars produced by the leaves and moves them to the roots.
Vascular cambium
The second of the two growing parts of the trunk. It produces phloem to its outside and sapwood (or xylem) to its inside.
Sapwood
The "soft wood" of the trunk, also known as the xylem. Brings water, minerals, and stored sugars up from the roots and distributes them to the leaves!
Heartwood
As the sapwood ages it begins to die and fill up with defensive and structural chemicals, becoming heartwood. Heartwood no longer transports water or nutrients but now serves the purpose of strengthening and supporting the tree.
Pith
The soft and spongy core of the trunk, usually very small in mature trees. On young trees, small branches, and shoots, it seems to help with storage, but in older trees it is just a vestige of that earlier function.