Marumi Fortunella japonica (Thunb.) Swingle Kumkvat
Giapponese, Golden, Hsia chü, Chin tou, Chinkan, Chintou, Jin dou, Jin gan, Jin ju, Jin kan, Kin Kan, Lu chü, Lu ju, Luowen, Maru kinkan, Maru-kinkan, Muntala, Rotonda, Rotondo, Round, Shan chü, Shan ju, Vangasay, Xia ju
This variety obviously originates in Japan, but some sources also claim that it's Chinese variety, where it was supposedly discovered in 1846 by Robert Fortune. This cultivar was known in the past as C. japonica Thunb., C. inermis Roxb. Or C. aurantium subsp. japonica var. globifera.
It's a small, dwarfed tree or shrub that is less vigorous than any other kumquat, but is very wide and has few thorns on its branches. The leaves are smaller, slightly pointed at the tip with serrated petioles. It resembles kumquat 'Nagami' in certain traits, but is not so widely cultivated. It has white flowers and slightly flattened, spherical fruit that can grow from small to medium-sized (2-3cm) weighing 10-20g. The rind is thin, sweeter, golden yellow with spicy flavor and excellent aroma. Its pulp is very sweet and is usually divided into 6 segments with 3-6 almost green, oval seeds.
This variety also likes higher temperatures and the idle temperature for overwintering is around 5°C. The fruit ripens in the same time, as kumquat 'Nagami'. This variety is also widely cultivated in Vietnam homes in the time of lunar New Year celebrations. Some references mention also usage as a rootstock.