Torreya nucifera var. nucifera (kaya nut)

Japanese name: カヤ （榧）
Scientific name: Torreya nucifera var. nucifera

[Overview]
An evergreen coniferous tree growing in the mountains, reaching as much as 25 m in height with a trunk 2 m in diameter.
It is dioecious.
The bark is smooth and gray, and develops vertical fissures in old trees.
The leaves are arranged spirally, but because the bases are twisted they appear to be in two rows.
The leaves are linear to linear-lanceolate, 1.5–2.5 cm long and 2–3 mm wide, and the tip is hard and sharply pointed, so they hurt when touched by hand.
The upper surface of the leaf is dark green and glossy, and the underside is pale green with two white stomatal bands.
The male flowers are borne in the leaf axils of the previous year's branches and are oblong, about 1 cm long.
The female flowers (ovules) are borne several at a time at the tips of short branches arising from the leaf axils of the previous year's branches, and one of them matures.
The seed is elliptical, 2–3 cm long and 1–1.5 cm in diameter, enclosed in an aril, and ripens in October of the following year.
The aril is green at first, turns purplish brown when ripe, and splits to reveal the pale brown seed.

[Uses]
The wood is hard and is used for go boards, construction, utensils, carving, shipbuilding and more.
It is considered the finest material especially for go and shogi boards.
The seeds are edible, and the oil obtained from them is used for food and for hair dressing.

[Cultivation]
Propagate from seed or by grafting.
It prefers a fertile, sunny, well-drained site with moderate moisture.
It is resistant to air pollution and is shade-tolerant and drought-tolerant.
It is suitable for planting from Honshu southward.
There are almost no pests or diseases, but aphids and scale insects may attach, and sooty mold may occur if ventilation is poor.

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