Corydalis ambigua aka Capnodes Ambiguum

Corydalis ambigua is a small perennial in the poppy family, Papaveraceae. Its native range runs from the Russian Far East to Korea. It also includes northern and north-central Japan. Kew records it as a tuberous plant of temperate regions. In northern Japan, it grows in woods and meadows. These sites range from low ground into the mountains. Plants For A Future notes uncertainty over its species status. It links the plant closely with Corydalis fumariifolia.

The plant reaches about 0.7 feet (0.2 metres) tall. Its spread is about 0.3 feet (0.1 metres). Leaves appear from March to June, giving it a short leafy season. The plant has an underground tuber and returns as a perennial. Each flower has both male and female organs. Bees pollinate the flowers, and plants can also set seed themselves. The seeds ripen from May to June.

Grow it in moist soil that drains well. It suits light sandy soil and medium loam. It accepts mildly acid, neutral, and mildly alkaline conditions. Partial shade suits its needs in cultivation. A woodland garden or a shaded border edge offers suitable conditions. Plants For A Future also lists peat beds as suitable sites. It gives a USDA hardiness range of zones 5–9. The same source describes the plant as frost hardy. Its small size suits planting where low woodland plants remain visible.

Fresh seed offers one way to raise new plants. Sow it soon after ripening, since drying soon reduces viability. Sow on the surface and keep the seed moist. One report gives germination within one to three months at 15°C. Another reports that seedlings emerge in spring. Stored seed may benefit from warm treatment followed by cold treatment. Seedlings make just one leaf in their first year. Leave them undisturbed in their pot during that year. Young plants are prone to damping off. Plants For A Future reports that rabbits tend to leave plants alone.

Plants For A Future records the cooked root as edible. It gives this use a low rating of one out of five. The root and tuber also have a history of medicinal use. Reported uses include pain relief, easing spasms, and sedation. These records do not establish safe home use. The supplied evidence gives no species-specific toxicity finding.