Nature on our doorsteps: Ivy-leaved Toadflax, adapted to life on a wall

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

In May clumps of a small scrambling plant come into flower on many old walls throughout the built-up environment.

This wall plant is Ivy-leaved Toadflax, where ‘ivy-leaved’ describes how the plant’s small leaves look like rounded leaves of Ivy.

Its flowers are mostly lilac or light purple in colour, with a centre spot of yellow on a white background.

Its three lower petals spread outwards, forming a little platform where insects can land to pollinate it, while the two upper petals stand upright.

These flowers look very like the flowers of another plant, the original Toadflax, which once commonly grew as a weed in fields where flax was grown as a crop for the linen industry.

Ivy-leaved Toadflax is a native of the Mediterranean and eastern Europe where it grows naturally in the cracks and crevices on rocky cliffs and amongst stony ground.

In our urban environment, the plant grows well on old walls.

Rocky cliffs and walls, however, are harsh environments to grow in.

The lilac-coloured flowers of Ivy-leaved Toadflax attract pollinating insects

There is very little soil to offer a foothold for roots or to provide nutrients to growing plants.

Plants are also exposed to either very dry conditions or to periods of heavy rain.

Ivy-leaved Toadflax is well-adapted to these challenging situations.

Its roots are thin and wiry, and this helps them reach deep into cracks on the wall or in the mortar between bricks.

These roots also have a special partnership with a root fungus which provides nutrients to the plant in return for sugars that the plant produces.

The plant is also adapted to make sure its seeds are not wasted.

The stalk that holds the flower pushes the flower away from the wall to make it visible to passing insects.

After pollination, however, the stalk curves back in towards the wall so that the seed capsules are pushed into dark cracks where the seeds can safely grow.