Copy and pasted:
"2.) Two-Toned Leaves
Two-toned leaves usually have split coloring in a relatively straight line. This mutation often affects just one or two leaves on the whole plant, though sometimes you'll get a whole stem or part of the plant that displays this characteristic.
The two-toned leaves don't seem to have much effect on anything, but it's kinda cool looking!
I believe this happens due to a type of “variegation” (
wikipedia link) and may be due to “sectorial chimera”. Other plants besides cannabis plants can have this happen, too!
"
http://www.growweedeasy.com/weird-or-what#two-toned-leaves
In my own words- its a "sectorial chimera." Where a small part of the plant has slightly different genetics than the rest of the plant; or at least that how I understand it. This is just a google image search showing a bunch of other plant species with sectorial chimera
https://www.google.com/search?q=sec...ved=0ahUKEwjau67M55nQAhVINSYKHeC6BTEQ_AUIBigB