The ornamental design for a plantpot, as shown and described.
FIG. 1 is a top, front perspective view of a plant pot in accordance with the present invention, shown with one of the panels raised and the other top panel closed;
FIG. 2 is a top plan view thereof, shown with both top panels closed;
FIG. 3 is a front elevation view thereof, the left side, right side, and rear elevation views being identical thereto; and,