Marsupella emarginata Notched Rustwort

Similar to Marsupella aquatica, which some regard as just a closely related variety (see account of that species for a general description and details on the differences between these two taxa). It is a species of soil covered rocks, usually near streams in the uplands, sometimes on dripping, vertical rock surfaces. The recurved, lateral margins of the leaves and the deep notch (up to one third of the length of the leaf) are distinctive characters. Under the microscope the leaf cells show extremely thickened corners (trigones). It has a distinctive west and northern distribution in Britain and it is relatively common in the uplands of Wales. In West Glamorgan it is most common in the uplands of Neath Port Talbot. Sporophytes are frequent.