This is a dark-green, hairless, annual plant with slender, hollow, finely-ridged stems, which grows on arable and waste ground. Reaching 50 cm in height, it bears umbels (2–3 cm) of small white flowers (2 mm across) each with five petals. Below this umbel are three to five bracteoles or small bracts which droop or turn back giving a the umbel a slightly bearded appearance. They bloom from June to August. The flat and triangular leaves are bi- or tri-pinnate. They emit an unpleasant smell when crushed. The egg-shaped fruits are ridged. This is an introduced plant belonging to the Apiaceae family.
I first saw this plant near Bannow Island, County Wexford when on a BSBI field trip with Paul Green, Vice-county Recorder, in 2010 when I also photographed it.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre