Alnus japonica var. japonica (East Asian alder, "Hannoki")

Japanese name: ハンノキ （榛木）
Scientific name: Alnus japonica var. japonica

[Overview]
A deciduous tree 15–20 m tall, growing in wet marshy places and forming wetland forests.
The bark has shallow cracks and peels.
Leaves are simple and alternate, elliptical, 5–13 cm long and 2–5.5 cm wide, with 7–9 pairs of lateral veins.
The leaf margins have uneven serration.
The petiole is 1–3.5 cm long.
There are male and female flowers, which bloom before the leaves unfold.
The male flowers grow on cylindrical catkins 4–7 cm long, hanging down in groups of 2–5 at the tips of the previous year's branches.
The male catkins are brown and have short stalks.
The male flowers are small and borne in threes beside scale-like bracts; the perianth is 4-lobed and there are 4 stamens.
The female flowers grow on cone-like inflorescences, 1–5 at a time, in the leaf axils just below the male catkins.
The female flowers have no perianth, and the reddish purple stigmas are conspicuous.
The fruiting spike is elliptical and cone-like, 1.5–2 cm long and 1.5 cm wide, with the fruits attached to the inner surface of the scales.
The fruit is a flattened nut with narrow wings on both sides, and the style remains at the tip.

[Uses]
The branches, leaves, and bark are used medicinally.
The fruiting spikes and bark can be used as dye.
The wood is used for firewood and charcoal, as well as for tools and pencils.
It was also planted around rice paddies to serve as trees for drying harvested rice sheaves after the rice harvest.

[Cultivation]
Propagate from seed or by cuttings.
Although it is a wetland plant, it also grows in dry places, and thanks to symbiotic microbes it grows well even in poor soil.
Plant it in a sunny place.
There are no particular pests or diseases.

[Notes]
It is a food plant for the larvae of the Midori-shijimi (Japanese green hairstreak butterfly).

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