The ornamental design for a planter, as show and described.
FIG. 1 is a front, perspective view of the design of the present invention;
FIG. 2 is a left side elevational view of the design of the present invention;
FIG. 3 is a rear elevational view of the design of the present invention;
FIG. 4 is a right side elevational view of the design of the present invention;
FIG. 5 is a front elevational view of the design of the present invention;
FIG. 6 is a top plan view of the design of the present invention, and,
FIGS. 7-13 each show a different front, perspective view of an embodiment comprising an arrangement with multiple planters according the design of the present invention.
The bottom lines in the drawings depict portions of the planter that form no part of the claimed design and/or represent unclaimed environment.