I claim the ornamental design for a topiary potted plant structure, as shown and described.
FIG. 1 is a perspective view of a topiary potted plant structure showing my new design;
FIG. 2 is a front elevational view thereof, shown at a reduced scale, the rear elevational view being identical thereto, and the left and right side elevational views being substantially identical thereto, the sole difference being the ordering of the elements crossing at the top;
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a bottom plan view thereof.
The broken lines showing a potted plant in FIG. 1 are included for the purpose of illustrating the invention in use and form no part of the claimed design.