Natsudaidai Sour Orange

Natsudaidai, also called Japanese summer orange, is a late-ripening citrus historically grown in Japan. In his 1967 account, Hodgson said it was then second in importance only to satsuma in Japan.^⁠[3]

Hodgson described Natsudaidai as showing characters of pummelo or sour orange and mandarin. He offered pummelo involvement as his opinion based on those characters; this is a historical morphological inference, not DNA evidence.^⁠[3]

The 1986 account reproduced by UCR says Natsudaidai is believed to have originated from a seed that drifted ashore in Yamaguchi about 1870; Hodgson’s 1967 account reports a seedling found in a Yamaguchi garden toward the end of the 17th century. These accounts do not resolve the date.^⁠[1]⁠[3]

A 1986 general Natsudaidai account reproduced on UCR’s Kawano page describes large fruit weighing 400–500 g, about 30 seeds on average, and acid content of 2–3%. These are historical profile figures; sample and measurement methods are not given.^⁠[1]