The said industrial design consists of the shape and configuration of a case for holding natural or artificial plants as shown in the drawings; the case for holding natural or artificial plants presents a series of transversely and vertically aligned frames each presenting a similar structure, the frames in a first position where the side walls of transversely adjacent frames are contiguous and the front walls of the frames in each row present of convex curved surface in plan view; in a second position, the front walls of the frames in each row are aligned and present a generally flat front surface for the case; in a third position of the frames, the front walls of the frames in each row present a concave curved surface in plan view;each structure of the case of the uppermost row of frames has a flat top wall, a flat front wall with a large U-shaped open area therein, and side walls which extend rearwards from the front wall and then converge rearwards to a flat rear wall; each flat rear wall presents a central partial wall portion extending forwards a short distance therefrom; the inner surface of each structure presents a stepped section along the bottom inner surfaces of the side and back walls; the bottom wall of each structure presents a flat surface section with a cylindrical section which extends above and below the bottom wall adjacent the left rear corner of each structure; the bottom wall of each structure also presents a short generally cylindrical section close to the right rear corner thereof which extends above and below the bottom wall; the bottom wall also presents a central generally truncated triangular raised section in plan view which slopes downwards and rearwards from the front wall to the flat surface section of the bottom wall; the flat rear wall of each structure presents spaced apart concentric circular areas; each structure of the case other than the uppermost row of frames has a flat front wall with a large U-shaped open area therein, and side walls which extend rearwards from the front wall and then converge rearwards to a flat rear wall; each flat rear wall presents a central partial wall portion extending forwards a short distance therefrom; the inner surface of each structure presents a stepped section along the bottom inner surfaces of the side and back walls; the bottom wall of each structure presents a flat surface section with a cylindrical section which extends above and below the bottom wall adjacent the left rear corner of each structure; the bottom wall of each structure also presents a short generally cylindrical section close to the right rear corner thereof which extends above and below the bottom wall; the bottom wall also presents a central generally truncated triangular raised section in plan view which slopes downwards and rearwards from the front wall to the flat surface section of the bottom wall; the flat rear wall of each structure presents spaced apart concentric circular areas.Representations of the design are shown in the figures wherein:Fig. 1 is a front elevation view of the design of a case for holding natural or artificial plants is in a first position;Fig. 2 is a rear elevation view thereof;Fig. 3 is a left side elevation view thereof;Fig. 4 is a right side elevation view thereof;Fig. 5 is a top plan view thereof in the first position;Fig. 6 is a bottom view thereof;Fig. 7 is an enlarged top plan view thereof;Fig. 8 is a front view thereof in which the case for holding natural or artificial plants is in a second position;Fig. 9 is a top plan view thereof in which the case for holding natural or artificial plants is in the second position;Fig. 10 is a top plan view thereof in which the case for holding natural or artificial plants is in the third position;Fig. 11 is an enlarged fragmentary view of a portion defined by area A - A, line B - B, and line C - C of Fig. 1;Fig. 12 is an enlarged fragmentary view thereof taken along line D - D of Fig. 8;Fig. 13 is an enlarged sectional view thereof taken along line E - E of Fig. 11; andFig. 14 is an enlarged sectional view thereof taken along line F - F of Fig. 12.Diagrams of the design are included.