Juglans mandshurica var. sachalinensis (Japanese walnut, "Onigurumi")

Japanese name: オニグルミ （鬼胡桃）
Scientific name: Juglans mandshurica var. sachalinensis

[Overview]
A deciduous tree 7–10 m tall, exceeding 20 m in large specimens.
It is found on slopes along mountain rivers, and may form colonies in places that are flooded when the water rises.
Leaf scars remain on the stems as knobs; the scars are inverted triangles with vascular bundle marks at the three corners.
The leaves are alternate, odd-pinnately compound, 40–60 cm long, and consist of 11–19 leaflets.
The leaflets are elliptic, 8–18 cm long and 3–8 cm wide, with fine teeth.
The underside of the leaves is densely covered with stellate hairs.
The petiole and leaf axis are densely covered with brown soft hairs and glandular hairs.
There are male flowers and female flowers.
The male inflorescence is a catkin 10–22 cm long that hangs down from the leaf axils of the previous year's branches and is densely covered with soft hairs and glandular hairs.
The male flowers are small, 4–5 mm long, are borne in large numbers on the inflorescence, and have 12–20 stamens.
The female inflorescence is a spike 6–13 cm long that stands upright at the tip of a branch of the current year and is densely covered with long hairs and glandular hairs.
The female flowers are 7–8 mm long, 7–10 are borne on the inflorescence, and the red styles are conspicuous.
The fruit is an ovate nut 3–4 cm long, densely covered with brown hairs.
Inside the fruit is a stone (the walnut) 2.5–3.5 cm long with a wrinkled surface.

[Uses]
The seeds (kernels) are edible.

[Cultivation]
Propagate from seed or by grafting.
As long as the site is sunny, well drained and moisture-retentive, it is not particular about soil.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient.
Apply organic fertilizer in early spring and autumn.
Stem blight can occur.

[Notes]
The name is said to include "oni" (demon) because the walnut is hard and deeply wrinkled.

View this page in Japanese (日本語)