The Watermelon (Citrullus lanatus) belongs to Cucurbitaceae (the Gourd family). It is an annual her that is probably native to central or southern Africa. This herb had been cultivated in Egypt before 4000 years ago. It was introduced into Japan via China in early Edo Era (1603-1868). The stem is vine and longated. The leaves are divided into lobes pinnately and alternate. The yellow flowers come in the axils in summer. The fruits are globose to oblong pepo. The inner endocarps ripen red or yellow and edible.