--tree bark--

 the beginning(sprout)--

  the sprout of a plant or tree, is the main water vein, or canal,
being seen, before becoming dehydrated on it's exterior--

bark(down to the molecules)--

  this dehydration can be described as "ch"(carbon and hydrogen,
aka, "sap"), flowing to the exterior of the trunk, and "h" evaporating,
from being heated by the suns rays, and hardening on the outside,
due to only "c" being left on the utmost exterior of the bark...
thus a cross section of a tree would look like--

--exterior of tree...(left--ccccchchchchcccc--right)...exterior of tree--

  after a tree sprouts, the water is diverted to the "solar
field"(canopy), of the plant or tree, i feel this is why a plant(tree) 
that has a heavy canopy, or "solar field", has bark, stiffening
the sides of the main-vein of the tree, to support the canopy's
weight, while vegetables/plants with lighter canopy's, do not--

bark/tree growth correlations--

  bark is made from leaking "sap", dehydrating, hardening,
and becoming thicker over time, i suggest, that as the bark thickens,
the side of the bark nearest to the inside of the tree, re-hydrates,
and becomes the next internal ring of the tree, at a predictable rate
(this is how we currently discover a tree's age), this re-hydration,
occurs from the bark sealing the tree/plant's internal rings of carbon
and hydrogen(around the main water vein of the plant), from the
elements, stopping the dehydration/evaporation of moisture and hydrogen
in the inner layer of the bark--

conclusion--

  some species of tree, or plant, have different, or no, bark...
depending on the region they grow(climate conditions), and size of
solar field(canopy)--


 (cs)