Walls are, with increasing age and if they are allowed to acquire patina, a good habitat for many animals and plants.
I would like to introduce some of them in this post.
Black Nightshade (Solanum nigrum)
The Black Nightshade can cope with many habitats, in my garden it grows in the compost heap.
On walls or stairs it usually keeps smaller than in nutrient-rich soil.
Cleavers (Galium aparine)
Cleavers is not a typical wall dweller, but can survive there if there is enough humus in the crevices.
Spring Draba (Draba verna)
Its size alone makes Spring Draba perfectly adapted to growing on walls and in stone cracks. It only grows a few centimetres high. In the photo it can be seen with a Summer Lilac (Buddleja davidii).
Red Dead-Nettle (Lamium purpureum)
If necessary, the Red Dead-Nettle can also grow on a dry stone wall, but it remains smaller there, as can easily be seen in the picture.
Ivy-Leaved Toadflax (Cymbalaria muralis)
In German-speaking countries, Ivy-Leaved Toadflax is known as Mauer Zimbelkraut, which can be translated as Wall Cimble Weed. It bears this name because it usually grows on walls.
Greater Celandine (Chelidonium majus)
The Greater Celandine can grow up to 70 centimetres high and colonises roadsides, gardens, parks, bushes, preferably in semi-shady areas. It belongs to the poppy family (Papaveraceae). Apart from Europe, it is also native to Asia and North Africa.
Sweet Violet (Viola odorata)
The Sweet Violet or Wood Violet (Viola odorata) is a wild perennial that is also popular as a garden plant. It can grow on walls and between other stones.
Lesser Celandine (Ficaria verna)
Lesser Celandine (Ficaria verna) is rarely found on walls. It grows better in evenly moist, humusy to slightly loamy soil.