This annual weed (sometimes overwintering) grows in hedge banks, fields, roadside and waste ground throughout Scotland, but it is rarely seen in Central and the Northwest Highlands.
Growing up to almost a metre high it has stiff erect stems with spreading branches almost at right angles. The lower leaves are deeply lobed and pinnated, or sectioned, with leaflets growing in pairs along the leaf blade, with a large terminal lobe. The upper leaves have only the terminal lobe which can appear more pointed.
The flowers are tiny and pale yellow, no more than half a centimetre wide. The four petals are uniform and form a cross shape, with usually 6 white-anthered stamens, 4 long and 2 short, around a central carpel. The flowers grow in small tight clusters on a raceme that lengthens during the fruiting stage.
As they ripen the carpels develop into thin hairy siliques carrying many seeds. These grow closely against the stem.
Hedge mustard is edible. Young leaves can be added to salads and the seeds ground into mustard powder. It has also been used medicinally to treat a sore throat or husky voice. For this reason it is also known colloquially as ‘Singer’s plant.’