Citrus hassaku

Japanese name: ハッサク （八朔）
Scientific name: Citrus hassaku

[Overview]
An evergreen tree cultivated as a fruit tree.
The branches are rather upright, thick and sparse.
The leaves are alternate, elliptical, with shallow serrations on the margin.
They look simple, but are actually degenerated compound leaves and have winged petioles.
The flowers are white, 5-petaled and fragrant.
Many stamens are fused up to the middle of the filaments, forming a staminal tube.
The fruit is spherical to oblate, large at 350–400 g, and ripens yellow.
The rind is thick.
There is little juice, but the fruit is easy to eat because it is not very sour.

[History]
It is a chance seedling discovered in 1860, at the end of the Edo period, at Ejitsu Jodo-ji temple in Takuma-cho, Innoshima, Onomichi, present-day Hiroshima.

[Uses]
The fruit is eaten as a fruit.

[Cultivation]
Propagate by grafting.
It prefers a sunny, well-drained location with good water retention.
It dislikes cold, so it is best planted on the south side of a building where it is sheltered from the north wind in winter.
As a home fruit tree, it can be grown outdoors as far as the central and southern Kanto region.
Young trees transplant easily, but mature trees are difficult to transplant.
For plants in the ground, watering is unnecessary unless sunny weather continues and the soil dries out.
In spring and autumn, apply organic fertilizer or a fast-acting chemical fertilizer.
If the branches become too dense and the inside of the crown gets too little sunlight, the branches die.
Dead branches cause pests and diseases and reduce fruit set, so around March prune and thin moderately so that sunlight reaches the inside.
If many fruits set, thin them in July–August.
Pests and diseases include melanose, canker, citrus leafminer, scale insects, spider mites and aphids.
It is a food plant of swallowtail butterfly larvae.

[Notes]
The Japanese name is said to come from the fact that the fruit was eaten from around the first day (sakujitsu) of the eighth month of the old calendar.

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