Mosses and liverworts

This small (c. 2cm diameter) cushion moss is Grimmia pulvinata. A survey of the distribution of this moss in the 1960s by Oliver Gilbert showed that it occured only in places where there was little SO₂ pollution. At that time Morpeth town and the outlying housing estates all had high SO₂ so it occurred only on the fringes. The effects of the pollution were often very local. For example, it was absent from garden walls of the older (coal heated) houses at Kirkhill, but it invaded the walls of the newer, centrally heated houses that were built in the late 1960s. With the huge reduction in SO₂ in the town it is now common everywhere there is a suitable surface. 

The commonest thalloid liverwort in Morpeth is probably Lunularia (the spore producing bodies are half-moon shaped, hence the name Lunularia). The lobes on this specimen were about 1cm across. It grows in moist, shady places, often on clay or silt on the edges of streams. It also grows on soil in plant pots where it can be a menace to small seedlings. Other thalliod liverworts found in the area are Pellia epiphylla (with thin, almost translucent thalli) and Marchantia polymorpha (with the spores or gemmae in circular 'bowls').

For a selection of photographs of mosses and liverworts go to Google Images and type the full name of the species, or go to: http://www.bioimages.org.uk/HTML/T76.HTM