I have about 5 ulmus thomasii grafts with siberian
elm rootstocks. So I have been watching them
closely for the past years to help me identify
rock elm from other elms. And I wonder how that
works with a graft. Whether the tree thinks it is
RockElm and let the rockelm portion lead in
metabolic signals. Or whether the rootstock metabolism plays roles on
the branches and
leaves.

Some trees sort of want the rootstock to take over
and will constantly send out runners and overtake
the foreign main stem.

I think this subject is massively complicated and
complex as to the graft and how metabolism and
signals are exchanged. I have seen an apple tree
with 4 grafted units. A rootstock and then 3 different
types of apple on 3 different main stems.

What I suspect is that as a graft gets older, that some of the growth
is of cells that have sort of
"decided the tree" And these cells thus have overcome any of the
conflicts of tree identity.

On a different note, my horse has found a new
favorite spot since I let him in a different pasture.
There is a dense patch of tree and shrubs where
it is very dark and shady and that is where the
horse spends much of his time. I reckon it is
to escape the biting flys which need the Sun for
direction and not willing to go into that dark grove.