Stone masonry. It is an arcane skill and I know nothing about it. So when I am out looking at Tree Shaped Tombstones I am also searching for clues. How these things were made, customized and installed interests me.
Here is one of the twelve foot tall versions you occasionally run across in fancier cemeteries. Note the "seam"in mid picture. These were assembled in two or three segments that were set one atop another. Since all the lines of the bark are true I have to assume it was carved as a single unit then taken apart for shipping purposes.
Here a marker is tipped over, showing us the base. It is rough carved either because it would not be seen or perhaps to hold mortar for secure installation. I refuse to believe that the base seen here - an earlier grave marker - was original. That seems most disrespectful and besides the older stones are pristine. I think this one was put on its side not by nature or by vandals but in preparation of having a new, secure base installed.
Note also the central hole in the stone. I suspect these were drilled in to provide a convenient place for a lifting device, something like a set of large tongs.
In support of this theory I have seen a handful of examples where you can see the hole in the top of one of these segments. Here I think is one where the upper half fell off - and probably broke - so long ago that the exposed surface of the lower segment is moss encrusted.
Is this another temporary base? It looks a bit more long standing but really is parking your monument on some loosely assembled bricks sensible?
This one has me thinking. In the above photo you can see the classic "feet" that represent tree roots. I have always assumed they were features of the original carving. But in this specimen there is a chiseled slot with a metal pin right at the bottom of a "tree". Again you can see the rough surface for mortar although no trace of it can be seen. Perhaps this was how various standard features such as flower pots or doves were attached? Note in this case a solid, plausible looking stone foundation.