Citrus japonica (kumquat, "Kinkan")

Japanese name: キンカン （金柑）
Scientific name: Citrus japonica

[Overview]
An evergreen shrub about 2 m tall.
The branches are thin and short, and branch densely.
It has short, sharp thorns.
The alternate leaves look simple but are reduced compound leaves. They are entire, leathery, elliptic, about 4.5 cm long and 1.8 cm wide, and thick, and the wings on the petioles are not well developed.
The flowers are borne in the leaf axils, solitary or in clusters of several, and bloom 2–3 times a year.
The fruit is spherical, about 2 cm in diameter, and ripens yellow-orange.
The rind is thin, sweet and fragrant, but the flesh is sticky and strongly sour.

[History]
It is thought to have grown wild in southern China, and it came to Japan before the Edo period.

[Uses]
The fruit is eaten fresh with the rind, or preserved in sugar, and is also used medicinally.

[Cultivation]
It is cold-hardy and easy to grow.
Propagate by grafting.
It prefers a sunny, well-drained site.
Although the tree is small, it bears many fruits, so fertilizer is needed throughout the year.
If left alone, the branches become too dense, the inside of the crown receives too little sunlight, and the branches die.
Dead branches cause pests and diseases and reduce fruit set, so thin and prune moderately so that sunlight reaches the interior.
Do not let the flowers that bloom in autumn set fruit, so the plant does not become exhausted.
Also, running short of water during the fruit growth period causes fruit drop.
In autumn and winter, the ripening period, keeping the plant on the dry side produces sweeter fruit.
Pests and diseases include melanose, citrus leafminer, scale insects, spider mites and aphids.
It is a food plant of swallowtail butterfly larvae.

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