Herb Robert (Geranium robertianum) seems able to survive almost anywhere. I have seen it at the foot of hedgerows, in the undergrowth beneath trees, and in really hostile habitats like the angle crack in concrete at the junction of walls and paths, and on stone steps in Charlton Down. I think the colour of the foliage is dependent on the degree of shade and moisture in which the plant is growing – so that the redder leaves and stems are on plants in the drier places. They are low-growing creeping plants with much-divided leaves and hairy stems. There are small pink flowers and lovely long pointed beak-like seed capsules that are the give-away sign that they are members of the cranesbill family of plants.