Anyway, when I found myself ten minutes early for a bus in Banbury I took a look at an adjacent wall and was not disappointed. The wall was composed of blue brick - not the most promising of habitats - but it was host to a wide variety of organisms. A few vascular plants had taken root, most obvious of which were some Buddleias, Buddleja davidii. The local authority will need to remove these quite quickly or their roots will begin to split the wall. Less of a danger was posed by a tiny, stunted crucifer about a metre away. The plant was not in fruit (and fruit are very useful in determining a species) but the minutely hairy leaves suggest it was Common Whitlow-grass, Erophila verna, a highly variable plant which favours dry walls.
|Photo 1. Buddleia and the lichen Xanthoria parietina|
Mosses were also common. The grey species at the top left of Photo 2 is Grimmia pulvinata, but Bryum argenteum and Tortula muralis were present too. The mosses, like lichens, have no true roots so the lack of soil is of little consequence.
|Photo 2. Common Whitlow-grass?|