Abstract: A metal anchor tube is driven into the ground or blacktop and defines a cavity which receives the lower end portion of an elongated cylindrical flexible marking tube extruded from a resilient plastics material. The upper end portion of the marking tube supports a light reflecting member which may be in the form of a reflective sheet located within the marking tube and visible through an opening or window within the tube. In one embodiment, the lower end portion of the marking tube is releasably coupled to the anchor tube by an internal wedge plug which compresses the marking tube against the anchor tube and is inserted and removed by means of a tool. In another embodiment, the releasable coupling is formed by an anchor tube having tabs which project inwardly into corresponding holes within the flexible marking tube.