An evolution in grafting

Question

My question stems (pardon the pun) from two ideas:

1. That trees live for a very long time and that there have been many evolutions of trees in that time.

2. It is possible to graft trees of the same genus together to form a tree composed of two different stocks.

Theoretically, if trees were held back from death, would it be possible to make a segment of trees tracking their evolution and following their ancestors?

For example, a branch of a lemon tree on the branch of the citrus ancestor tree, onto its ancestor, etc. until they reached the first tree. I think it could result in a tree that could produce every fruit of its lineage, but it's just a theory, right?

Obviously this is a purely theoretical idea, but I'm curious. Or, if it's not just a theoretical idea, and that trees could be "brought back" (like there are efforts for different animals).

Answer 1

It is possible to buy citrus trees with more than one variety grafted to it. See here and here.

Note that the first link talks about incapability problems. And all of these trees are considered to be the same species.

So I'm going to answer "no", it's not possible in practice, with current grafting techniques. You can get a few varieties grafted onto one rootstock. But grafting an entire evolutionary tree with thousands or millions of grafts isn't going to be possible. The graft point is the weakest point, it's prone to disease, and the tree can only get so big.

Answer 2

Two words: Luther Burbank. He's your new hero. One of his early exploits was producing a crop of sapling plums IIRC faster than anyone else could. He did this by grafting seedling plums onto sapling apricots, which mature faster.

Later experiments involved cross-breeding near-species which apparently produced offspring that represented a spectrum of the divergence between the two species. That is, he crossed modern corn (maize) with indigenous American grasses (wild oats, so to speak) and produced some plants that were like corn, some that were like grass, and some that were different blendings of those characteristics.

He was known for large-scale breeding experiments, and would walk through the plots at a swift pace directing that this and that plant be discarded.

I learned all this from a marvelous little biographical ... pamphlet, I guess you'd call it. From the 50s or 60s so a small printing project of 30-40 edited, illustrated pages was still a big project. But I've since misplaced it. :(