Sisymbrium irio

Small yellow flowers form in clusters at the end of the stems. Its basal leaves may be lobed. Rosette leaves vary from deeply lobed to being separated fully into leaflets (compound) in the lower part. Upper leaves are somewhat oblong, mostly with two basal lobes angled away from the base, stalkless, smaller than the lower leaves, and do not clasp the stem. It is a flowering plant in the cabbage family which is native to the Middle East, north Africa and southern Europe, and which has spread widely around the world as an invasive plant of dry, disturbed land in towns, deserts and farmland. It has traditionally been used as a medicinal herb for a variety of ailments. Its English common name originated when it flourished after the Great Fire of London in 1666, although it is not native to Britain and it does not tend to persist there. London rocket can easily be confused with other species of Sisymbrium. Characters to look for include the compact flower head, the way the developing seedpods extend above the flowers, and the long, thin pedicels which are narrower than the fruits.