Citrus tachibana (tachibana orange)

Japanese name: タチバナ （橘）
Scientific name: Citrus tachibana

[Overview]
An evergreen small tree 2–6 m tall, found in evergreen forests in mountains near the coast.
Young branches are green and somewhat flattened, with stout, sharp thorns 0.5–1 cm long.
The leaves are alternate, ovate-oblong to ovate-elliptic, 4–8 cm long and 2–4 cm wide, with entire margins or shallow serrations.
They look like simple leaves, but they are reduced compound leaves and have very narrow wings.
The petiole is 0.4–1 cm long.
The flowers are borne singly in the leaf axils of new branches; they are white, 5-petaled and fragrant.
The petals are 0.8–1 cm long.
Numerous stamens are fused up to the middle of the filaments, forming a staminal tube.
The fruit is a flattened sphere 2–2.5 cm long and 2.5–3 cm across, ripening yellow.
The juice is very sour and not suited to eating raw.

[History]
It has long been planted in the grounds of temples and shrines.
Because it is evergreen, it evokes the image of "eternity" and is therefore valued.
The elixir of immortality "Tokijiku no Kaku no Konomi" in the Kojiki and Nihon Shoki is taken to refer to the tachibana, and so it is planted at the Shishinden of the Kyoto Imperial Palace as the Ukon no Tachibana.
The fruit and leaves are used as a family crest.
The Order of Culture is also designed after the tachibana.

[Uses]
It is used as rootstock for other citrus plants.

[Cultivation]
Propagate by grafting.
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.
When used as a garden tree, it suits regions with mild winters, from southern Kanto westward.
In other regions, growing it in a pot is better.
It prefers a site that is sunny, well drained and moisture-retentive.
Young trees transplant easily, but mature trees are difficult to transplant.
For plants in the ground, watering is not needed unless sunny weather continues and the soil dries out, but for young trees, watering well in summer to encourage good branch growth speeds up growth.
For potted plants, water thoroughly when the soil surface dries.
In spring and autumn, apply an organic fertilizer or a fast-acting chemical fertilizer.
If the branches become too dense and the inside of the crown receives too little sunlight, the branches die.
Dead branches cause pests and diseases and reduce fruiting, so around March thin and prune moderately so that sunlight reaches the interior.
If many fruits set, thin them in July–August.
Pests and diseases include citrus leafminer, scale insects, spider mites and aphids.
It is a food plant of the swallowtail butterfly.

View this page in Japanese (日本語)