Asarum tohokuense ("Togokusaishin")

Japanese name: トウゴクサイシン （東国細辛）
Scientific name: Asarum tohokuense

[Overview]
An evergreen perennial growing in deciduous forests.
The stem creeps along the ground.
One or two leaves emerge; they are simple and alternate, ovate, 5–13 cm long and 3–13 cm wide, with a deeply heart-shaped base.
The leaves are thin and not glossy on the upper surface, and short hairs grow along the veins.
The leaf stalk is 3–16 cm long.
The flowers bloom sideways at ground level.
The flowers have no petals.
The upper part of the calyx tube, which is oblate, 6.5–10.5 mm long and 10–15 mm across, splits into 3 petal-like lobes.
The tip of the tube is slightly constricted.
The inner wall of the calyx tube is not dark purple throughout, but white to pale pink with partly dark purple areas.
The inside of the tube has 15–21 low vertical ridges.
The calyx lobes are ovate-triangular, 5–9.5 mm long and 7–12 mm wide, spreading flat or slightly obliquely, thick, with short hairs on the surface.

[Cultivation]
Propagate from seed, by division, or by root cuttings.
Sow seed as soon as it is collected.
It prefers shade and soil that is well drained and retains water well.
It dislikes dryness, so water thoroughly when the soil surface begins to dry.
In spring and autumn, apply slow-release fertilizer placed on the soil.
Pests and diseases include southern blight, soft rot, anthracnose, virus diseases, slugs and cutworms.

[Notes]
Plants in this region had long been regarded as all being Usuba-saishin, but research by Hiroki Yamaji, Teruko Nakamura and colleagues (2007) showed that it is an independent species.

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