Citrus japonica ‘Crassifolia’ ("Neihakinkan")

Japanese name: ネイハキンカン （寧波金柑）
Scientific name: Citrus japonica ‘Crassifolia’

[Overview]
An evergreen shrub about 2 m tall.
The branches are thin and short, and branch densely.
Short, sharp thorns are occasionally present.
The alternate leaves look simple but are reduced compound leaves. They are entire, leathery, elliptic, about 5.5 cm long and 2.5 cm wide, thick, and whitish on the underside.
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 short-ovate, about 2.5–3 cm in diameter, and ripens yellow-orange.
The rind is thin, sweet and fragrant, and among the kumquats this one is well suited to eating fresh.

[History]
It is said that in Japan it began in the late Edo period, when a merchant ship from Ningbo, Zhejiang, China, met a storm off Enshu-nada and put in at Shimizu Port. The village headman (nanushi) of Orito, Miho village, was given sugar-preserved fruit of this species and sowed its seeds.

[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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