Sisymbrium officinale (L.) Scop.
Hedge mustard is an erect annual or overwintering plant native in waste places on rough and cultivated ground. It also grows on disturbed sites such as gardens, roadsides and field margins. Hedge mustard is common throughout the UK and is recorded up to 1,000 ft.
In a survey of weeds in conventional winter oilseed rape in central southern England in 1985 hedge mustard was found in 7% of the fields surveyed but was largely confined to the field margins. However, this may have been the result of herbicide application within the cropped area. A study of changes in the weed flora of southern England between the 1960s and 1997 suggests that hedge mustard has become more common. It is one of the commonest crucifers in Britain.
Hedge mustard has some therapeutic and medicinal uses.
Hedge mustard may be found in flower all year but mainly from May to October. Each seedpod contains an average of 15 seeds. The seed number per plant is around 2,700 but a large plant may produce 9,500 seeds.
For optimal germination in the laboratory, hedge mustard seed requires a combination of chilling at 2°C, light and nitrate prior to transfer to an incubation temperature of 24°C. Light and nitrate levels are limiting factors in seed germination. After burial in soil overwinter the light requirement is reduced and seed will germinate in the dark. The nitrate content in hedge mustard seeds has been positively correlated with germination levels.
The germination response of buried seeds is subject to seasonal changes. Temperature is the main factor regulating the changes. Dormancy is relieved by periods of low temperature and induced in periods of high temperature unless conditions are exceptionally dry. Fresh and recently buried seeds germinate at elevated temperatures whereas seeds buried for longer germinate better at low temperatures. Light, nitrate and desiccation stimulated germination of exhumed seeds. Buried seed exhumed at intervals and tested for germination, had a light requirement at burial but lost this with time over the period of burial.
In the field, seedlings emerge from autumn to early spring. Seed mixed into the surface 25 mm of soil and cultivated periodically emerged from December to June. Seed sown in early-May germinates in 7 days.
In a sandy loam soil, field seedlings emerge from the top 0 to 35 mm of soil with the majority emerging from the upper 25 mm.
Hedge mustard overwinters as a rosette of leaves.
Seed recovered from excavations and dated at 30 years old has been reported to germinate. Seed in dry-storage gave 100% germination after 5 years. Seed submerged in water did not germinate after a 3-month period.
Hedge mustard plants in the field margin should be cut down and any that encroach onto arable land hoed out. Seeding must be prevented.
Updated November 2007.