Spreading hedge-parsley

Torilis arvensis, the spreading hedge-parsley or tall sock-destroyer, is a slender annual herb in the family Apiaceae growing up to about 1 m tall. The branching stems are rough with stiff, downwardly-pointing hairs. The alternate leaves are pinnately to bipinnately compound, with several pairs of narrowly lance-shaped leaflets up to about 6 cm long that are themselves deeply cut into pointed segments or teeth. From early summer it produces wide, open compound umbels of small white flowers tinged pink, the petals notably unequal in size, on long, slender rays without conspicuous involucral bracts. The most distinctive feature is the dry schizocarp fruit, 3–5 mm long, densely coated with straight or curving prickles that cling tenaciously to clothing and animal fur for seed dispersal — the basis of the colourful common name. Native to parts of Europe, the Mediterranean basin and southwestern Asia, it has spread as a weed of disturbed ground, road verges, fallow fields and pasture margins across North America and elsewhere.