A bifurcating vertical fin system provides sheltered pockets for vertical vegitation.  These pockets shelter from increasing wind speeds on mid to high rise towers so plants do not become dislodged.  As the tower rises the vertical fins bifurcate more and more creating smaller and smaller sheltered pockets. 

Fins are semi-porous to allow some air flow through them to reduce the fins vibrating in the wind or becoming dislodged themselves.