Pennywort

This single example of a pennywort was spotted, as you can see, clinging to a rock some 10 feet or so from the ground. Most of the wild flower books that we have show Hydrocotyle vulgaris (a marsh pennywort having green 'leaves'). I do not know, therefore, whether this may be considered as the same or a different species (any comments and/or advice would be greatly received).