Nature on our doorsteps: Red Valerian

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.

THE tall spikes of Red Valerian are often seen growing on old stone walls, old buildings, and abandoned building sites.

Despite its name, the flowers can also be white and pink.

The plant can reach up to 75cm high when conditions are right, and it flowers from June until September.

Red Valerian originated in the Mediterranean where it grows in very dry situations in poor soils and rocky ground.

It is thought that it was first brought to Britain in the 1600s, after which it spread to Ireland and became naturalised here.

Its Latin name is Centranthus ruber, where Centranthus comes from the Greek words for ‘kentron’ meaning a spur, and ‘anthos’ meaning a flower.

Red Valerian can grow in very dry conditions on old wall

This perfectly describes the shape of Red Valerian’s individual flowers, which have long slender tubes (or spurs) behind a circle of 5 petals which are fused together.

Nectar is stored at the bottom of this slender spur, and so only long-tongued insects like moths, butterflies, and some bumblebee species can access it.

The caterpillar of the Angle Shades moth also eats its leaves.

Red Valerian’s seeds have tufts of fine hair-like filaments like the Dandelion.

These help the seed to spread widely in the wind. It is suggested that the railway lines helped Red Valerian spread quickly, where the gust caused by passing trains helped disperse the seeds far and wide across the country.

In some places around the world, Red Valerian is considered an invasive plant, and efforts are made to control its spread.

Red Valerian is not the same plant as the herb known as Common Valerian (Valeriana officinalis, or ‘official’ Valerian).

Common Valerian is used in herbal medicine while Red Valerian is not known to have useful medicinal qualities.

Red Valerian is said to be edible, and its young leaves are eaten raw in salads or cooked as a leafy vegetable.

Older leaves are said to be more bitter and are therefore not often used.