- Written also: Shepherd’s-purse
- Family: Mustard Family – Brassicaceae (Cruciferae)
- Growing form: Annual herb.
- Height: 10–40 cm (4–16 in.). Stem glabrous–sparsely haired.
- Flower: Corolla regular (actinomorphic), white, under 0.5 cm (0.2 in.) wide (sometimes lacking); petals 4, round-tipped, approx. 2.5 mm (0.1 in.) long. Sepals 4. Stamens usually 6, sometimes up to 10 (in which case petals have become stamens). Gynoecium fused, a single carpel. Inflorescence a raceme, extending in fruiting stage.
- Leaves: In basal rosette and alternate on stem, rosette leaves short-stalked, stem leaves stalkless, amplexicaul. Rosette leaf-blades usually pinnately lobed, sometimes curved or entire, stem leaves with toothed margins–entire, with sagittate base and tapering tip.
- Fruit: Many-seeded, triangular, broadening towards tip, with clearly notched tips (heart-shaped), wingless, 6–9 mm long silicula. Stalk approx. 10 mm (0.4 in.), spreading.
- Habitat: Yards, gardens, roadsides, paths, fields, waste ground, islets.
- Flowering time: May–October.
Shepherd’s purse left its Mediterranean homeland a long time ago and has travelled with people to suitable places all around the world. It is a weak competitor and cannot thrive in a crowded situation in the wild but it grows well in cultivated areas with quite dry, stony ground. Its small flowers are self-pollinating and if the soil is not frozen or covered in snow it can even bloom all year round. One of shepherd’s purse’s siliculae produces an average of 5,000 seeds – significantly more in larger plants – which are sticky and attach to passers-by and remain viable in the soil for up to 15 years. The seeds are able to germinate almost anywhere and shepherd’s purse can be found growing in very different environments, from concrete town centres to bird rocks.
Many people get to know shepherd’s purse for the first time from vegetable patches and flower beds, and although it is nowadays viewed as a weed the young shoots and overwintered rosette leaves used to be used as a culinary herb. It is a modest plant but has been widely used medicinally, e.g. to control excessive menstruation. It contracts blood vessels so it was used to treat wounds in e.g. World War II when more powerful medicines were unavailable. Its blood-clotting substances are found especially in plants that have been attacked by a white mould and whose shoots are distorted and malformed.