To try and clear up what that weird title is saying: the colour of foliage changes based on Location, Rotation, and Scale. This seemingly happens to nearly all plants (if not all) with each one reacting more or less extreme. Generally it seems that the settings interfere with the Saturation and tend to add a slightly greenish tone randomly.
Here you can see the same Autumn Oak at the same position in the Default Condo but with different Scale and Rotation. Notice how one setting has it more saturated than the other.
This has been a bug for quite some time and has been kinda annoying to build around.