- Latin synonym: Sisymbrium sophia
- Family: Mustard Family – Brassicaceae (Cruciferae)
- Growing form: Annual herb.
- Height: 30–60 (12–24 in.) cm. Stem upper part commonly strongly haired, lower part stellate-haired.
- Flower: Corolla regular (actinomorphic), pale–greenish yellow, under 0.5 cm (0.2 in.) wide; petals 4, narrow, 1.5–2 mm (0.06–0.08 in.) long. Sepals 4, usually longer than petals. Stamens 6, of which 4 long and 2 short. Gynoecium fused, a single carpel. Inflorescence a raceme, extending in fruiting stage.
- Leaves: Alternate, stalkless. Blade 2–3 times pinnately lobed, greyish green, stellate-haired, lobes narrow, quite linear.
- Fruit: Many-seeded, commonly slightly arching, terete, resembling a pearl necklace, 1.5–2 cm (0.6–0.8 in.) long, spreading siliqua under 1 mm (0.04 in.) thick. Stalk 5–10 mm (0.2–0.4 in.), thin, ascending oblique.
- Habitat: Yards, house walls, roadsides, heaps of earth, waste ground, cattle yards, harbours, railway yards.
- Flowering time: July–August.
Flixweed originally grew in on the steppes of Western Asia but it has followed people across Europe as far as Finland. Perhaps it has been transplanted on purpose because the plant’s seeds were used to treat dysentery in cattle and expel parasites from the gut, and it was also used externally to treat wounds and other injuries.
Flixweed is a typical old culture plant that grows in Finland’s oldest towns and villages in nitrogenous places. The significance of flixweed was probably greater when street paving did not reach all the way to house walls. The more intense way of building that prevails nowadays does flixweed no favours and they are not commonly found in new suburbs. Flixweed grows mainly in the south and south-west of the country and it can be found growing casually as far north as Rovaniemi and Kemijärvi. The species’ seeds still apparently arrive in Finland with trains. It is not in any way common anywhere in Finland and seems to have become rarer in its former habitats. Flixweed’s seeds survive a long time in the soil, however, and it can reappear in an old yard or road running through a village when the land becomes lighter.
Flixweed’s leaves are almost as finely-lobed as dill’s, although it is in no way related to this member of the Carrot family, and the structure of the plant reveals it as a member of the Mustard family. Insects visit the rather modest flower, but they can self-pollinate if so required and an exceptional amount of siliquae develop. Fixweed can be separated into different variations which differ from each other with regards to e.g. hairiness and the length of their petals.