Yes, green means it needs light :)

Fair enough...no other relationship? :)

I can't think of any general rule. I have shade plants with dark green leaves and with nearly yellow leaves. I have plants where the green leaves go yellow in the shade and plants where the yellow leaves go green in the shade.

So any idea what the physiological purpose of light vs dark vs purple foliage might be? I remember reading that purple foliage plants need more light...