A modular plant tower assembly includes a self-supporting vertical framework of rigid vertical supports defining a relatively large base, and extending inwardly and upwardly from the base to a smaller top of the vertical framework. At least one horizontal closed-end framework includes rigid horizontal supports. The horizontal supports are interconnected at their respective ends, and surround the vertical framework at a location intermediate the base and the top. At least one of the horizontal supports forms a lateral bridge connector. The bridge connector is adapted for connecting one end of a bridge frame to the plant tower assembly, and an opposite end of the bridge frame being connected to an adjacent like tower assembly.