Here’s a cute bicolored Japanese maple, Acer palmatum, that grows on N. Alberta Street.
Green and red leaves together. Are there two trees growing close together? It’s one tree. In this case a shoot from the tree’s grafted root stock has been allowed to persist, resulting in a two-tone appearance.
In the view below, you can clearly see that all the green leaves are located on one shoot on the left side, growing from the base of the tree.
This can happen with leaf form as well as color.
Here are the finely dissected leaves of the cultivar.
And the leaves from the grafted root stock shoots:
Quite a difference.
In this tree, it looks as though there has been some maintenance pruning so that the root stock foliage has not become dominant. In situations where they are not removed, they can take over because they are hardier.
Reversion is commonly seen in plants with variegated leaves, as in this Liriodendron tulipifera ‘Aureomarginatum.’ In this case, the situation arises not from root stock shoots, but due genetic reversion.
The foreground leaf on the right shows a reversion to the solid leaf color. The variegation is caused by a genetic mutation that is not stable. Plants can revert to the original solid or green leaf which will eventually take over because their growth is more vigorous.
It happens with conifers too. Here’s an example of reversion in a spruce cultivar.
Wild-looking, isn’t it? Rather than explaining the details of this occurrence in conifers, I’ll point you to this excellent article found in Northern Woodlands.