Sisymbrium loeselii aka False London Rocket

Sisymbrium loeselii is in Brassicaceae, the mustard family. One of its common names is small tumbleweed mustard. Its native range starts in central Europe. It reaches Siberia and the western Himalaya. It grows in temperate parts of this broad range. The RHS lists it as non-native to Britain and Ireland. Kew says it is annual or biennial. This means its life cycle takes one or two years. Plants For A Future calls it an annual.

Plants For A Future gives its height as about 1.6 feet [0.5 metres]. The account gives no width for a full-grown plant. Its flowers have both male and female organs. Insects help the flowers set seed through pollination. The plant is self-fertile, so needs no other plant to set seed. The sources give no bloom season or flower colour. They give no details of leaves, stems, or fruit. These gaps make it harder to name the plant from this account alone.

This mustard grows in many open sites and on disturbed ground. Records place it in fields and pastures. It grows by roads and on railway ground, too. Other sites include valleys, riverbanks, and prairies. In western China, records span heights above sea level of about 984–9,186 feet [300–2,800 metres]. These sites include farms and land with less human care. Plants For A Future says it may become a weed. It does not say how great that risk may be.

The plant accepts sand, loam, and clay soils in gardens. The soil may be slightly acid, neutral, or slightly alkaline. It grows in full sun or light shade. Soil can be dry or moist. Plants For A Future lists garden beds as a possible site. Sow seed where it will grow, in spring or autumn. The sources give no hardiness zone or set watering plan. They name no pests or diseases.

Plants For A Future lists no known food use. This does not mean that the plant is poisonous. The same source lists no known hazards. It notes past use of the leaves and flowers as medicine. Those uses were for scurvy and scrofula, not routine garden care. The report does not show that these treatments are safe or work. That account gives no other uses for the plant. Its stated garden role is thus limited to garden beds. Its risk of becoming a weed is worth noting.