Can foliage be given an up-vector to orient plants placed on walls?

If I made a foliage mesh that bends down, like a tree branch, or has a specific up/down direction, like ivy on a wall, can I set that vector as the up-vector for painting the foliage on vertical surfaces? I’d like to be able to paint Ivy on a static mesh and have the leaves all angle downwards but if I do that the yaw becomes basically arbitrary (or random) so sometimes leaves will be sticking straight up. I need the Z axis to follow the normal of the surface I’m painting on, but I also need the Y axis to stay as close to world-up as possible.

Can this be done? i am lonely.