Corydalis fumariifolia subsp. azurea ("Ezoengosaku")

Japanese name: エゾエンゴサク （蝦夷延胡索）
Scientific name: Corydalis fumariifolia subsp. azurea

[Overview]
A perennial 10–30 cm tall, growing in woods and grasslands.
It has a round tuber underground.
A single flower stem arises from the tuber.
One of the leaves on the flower stem is a scale leaf.
Side branches sometimes arise from the axils of the scale leaf or the ordinary leaves.
Two leaves are produced, 1–3 times ternately compound; the leaflets are 1–3 cm long, vary greatly in shape, and have entire margins or are 3-lobed.
A raceme at the stem tip bears many flowers densely.
The flowers are 1.7–2.5 cm long, blue to bluish purple.
There are 4 petals, but the upper one is longer than the others and has a long spur.
A bract, usually entire, is attached at the base of each flower stalk.
The seeds have an appendage (caruncle) that ants like, and they are carried and dispersed by ants.

[Uses]
The tuber is used medicinally.
The leaves and flower stems are used as wild vegetables.

[Cultivation]
Propagate from seed or by dividing the bulbs.
It prefers well-drained, well-aerated soil.
It does best in a sunny place from the emergence of new shoots until flowering and in partial shade after flowering; during dormancy, let it pass the summer in cool shade.
When planted in the ground, it is best set under deciduous trees.
When watering, take care to avoid both excess moisture and dryness; water thoroughly when the soil surface dries, and do not let the soil dry out completely even during dormancy.
During the growing season, apply organic fertilizer such as oil cake placed on the soil.
Pests and diseases include aphids and soft rot.

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