I have never heard of medlar before. Clearly it is a fruiting tree.

Fruit trees are the most commonly grafted type of tree. I have a couple of apple trees I had grafted. My knife skills are not up to par, and only the grafts done by a professional sealed up and healed properly to allow the grafted branch to grow.

The rootstock is usually chosen from a hardier variety. Primarily it gives the tree certain immunities and strengths against disease and temperatures. The rootstock also determines the growth rate of the entire tree. Often times rootstocks will form suckers very easily. Prune these off completely every year, otherwise you will get branches that compete with the grafted area. Trees look a bit strange when they have more than one type of branch and leaves growing on it.

People often graft fruit trees, flowering trees, roses, and yes, even bonsai. In bonsai, sometimes they will graft a single bud onto a trunk, simply because they want to add a branch in a location where there wasn't one before. I am not that persnickety about tree style and design, but for a grafting expert, they might as well use their knowledge to benefit their efforts, right?

This tree has a beautiful vase shape, ideal for growing fruit on. The only design flaw I see is the six branches all joined at the same location. This will eventually become a weak spot for the tree, and may cause the wood to form a bulbous lump underneath. Sometimes trees grow like this forever and have no problem. During a storm be careful, as one of those limbs might be prone to break. Maybe it will be okay if the tree is kept pruned to this size.

Hawthorn has very small berries that the birds enjoy. It looks nothing like this tree. I have one excellent hawthorn in my collection if you look back through my posts.