Descurainia sophia aka Tansy Mustard

Descurainia sophia belongs to the mustard family, Brassicaceae. It is short-lived. It grows as an annual or biennial, lasting one or two years. Its names include flixweed, flaxweed, and herb Sophia. It is native to temperate parts of Eurasia and North Africa. The RHS lists Britain and Ireland as native sites too. It now grows far beyond this range, including western North America. It grows by roads, on waste ground, in fields, and in open woods.

This plant grows fast to about 2.6 feet (0.8 metres) tall. It spreads to about 1.6 feet (0.5 metres). Its fine texture gives it a light, open form. It looks more like a self-sown weed than a formal bedding plant. Still, it can add texture to plantings with a wild look. It grows from seed and seeds itself with ease. Ground that has been disturbed gives new plants room to grow. This can make it hard to keep in one patch.

Plants For A Future lists its bloom time as June to August. Seeds ripen from August to September. In warmer parts of the American Southwest, blooms can last much of the year. Each flower has both male and female organs. Bees and other insects bring pollen to the flowers. Plants can also set seed with their own pollen. The flowers give insects nectar and pollen. The many seeds also play a part in local food webs.

Flixweed grows in sun or light shade. It can grow in sand, loam, or clay. It copes with slightly acid, neutral, or slightly alkaline soil. It grows best in moist soil, including ground wet for part of the year. Open soil with light disturbance helps it grow. Plants For A Future lists USDA hardiness zones 4–9. It can grow in garden beds, but take its self-seeding into account. The evidence points to a plant for open, disturbed sites, not tidy display beds.

People use the leaves, shoots, and seeds as food. Cook the leaves as greens, or add small amounts to raw dishes. Raw leaves taste strong and hot. Eating too much may cause irritation. Do not gather plants from polluted sites. They can build up minerals. The seeds provide food and a semi-drying oil. People have used the leaves to help keep stored corn from spoiling. Folk medicine uses include help with gut and breathing problems. These reports do not prove such treatments are safe or work.