Question
So, does the word "cambian" refer to anything at all?
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Followup To

Question -
I have a general question about tree terminology. Xylem and
phloem are found in the cambian layer or cambium layer? And
do you capitalize either word?

Answer -
It is cambium layer! The phloem is on the out side of the
cambium and the xylem is on the inside of the cambium layer.
No capitalization!
In herbaceous dicots a limited amount of secondary thickening
occurs, while it is more evident in perennial, woody dicots. The
stem increases in thickness as it grows older. In the vascular
bundle of a young dicot stem the xylem and phloem are
separated by cambium.

Secondary thickening begins when mature parenchyma cells in
the medullary rays which lie between the adjacent vascular
bundles become meristematic and form the fascicular cambium.
The fascicular cambium forms a continuous ring of cambium as
it joins up with the fascicular cambium. This cambium ring
undergoes division to form secondary phloem to the outside and
secondary xylem to the inside.  

Answer
Bark is what you see when you look at a living tree trunk or branch. It's composed of several kinds of tissue. Much of it is tough cork which, among other things, protects the tree from physical damage. Inside the bark, next to the cambium layer, is phloem tissue -- the part of the tree's plumbing system that transports the tree's photosynthesized food downward from the leaves or upward to growing buds or fruits.

The cambium layer is the only living part of the stem .It exists between the darker bark and the lighter wood. Cambium cells, which form a kind of cylinder inside the the twig, divide and produce bark tissue on one side, and wood tissue on the other. Wood is familiar to everyone, but the thing to know about it here is that it is composed of dead cells (even in living trees) and that these cells, unlike the phloem, conduct water and dissolved salts upward from the roots. When we think in terms of the wood's cell structure and its job of conducting water and salts, we refer to the tissue as xylem. The pith is a food-storage area in the center of the stem.

I hope that answers your question.