The Oneseed burr cucumber (Sicyos angulatus) belongs to Cucurbitaceae (the Gourd family). It is an annual herb that is native to eastern and central North America. It was confirmed to naturalize in Japan in 1952 and it is naturalized over land now. This herb grows in dry riverbeds and barrens, and spreads by trailing vines. The leaves are round-cordate and divided into 5-7 lobes shallowly. The female to male flowering clusters are borne on the axils and bloom small yelow-green flowers from August to September. The fruit is a long ovate berry with dense short hairs and spines. Seeds are flattened and ovate, one per fruit. It is also designated as an "invasive alien species (IAS)" in our country.