Commonly known as the wallflower this herbaceous hardy perennial and member of the cabbage family has long been cultivated in gardens, but its wilder cousin still remains in Scotland. It can be found on castle walls, cliffs and old stonework in the Borders, East and Southwest. It is the showiest of the wild cabbage family but in other ways quite typical, having cross-shaped yellow flowers and thin capsule-shaped seed pods or siliques. It doesn’t mind a poor soil as long as it gets full sun and is noted for attracting pollinating insects such as bees.
The flowers, bright yellow with 4 petals in a cross-shape, are up to 3cm in diameter and have a pleasant fragrance. They grow in a blunt terminal cluster at the top of the stem.
The stems and leaves are covered in flattened hairs, and the leaves themselves are lanceolate (lance-shaped) narrow, getting narrower up the stem.
The fruits, like all those of the cabbage family are known as ‘siliques’, dry, long and thin with a papery membrane in the middle, and are dehiscent, which means they split up the sides to release the seeds. Honesty, also a Brassicaceae is the most famous version of a siliqua.
In large doses wallflowers are toxic, and have been only cautiously used in herbal medicine, though recent research has shown that in small amounts they can be beneficial to the heart.