- Name also: Fumewort (unofficial)
- Family: Poppy Family – Papaveraceae
(formerly Fumitory Family – Fumariaceae)
- Growing form: Perennial herb. Tuber spherical.
- Height: 5–15 cm (2–6 in.) Stem ascending–erect.
- Flower: Corolla irregular (zygomorphic), red–purple, approx. 15 mm (0.6 in.) long; petals 4, of which two inner petals partly united, uppermost spurred, spur 6–10 mm (0.24–0.4 in.) long. Sepals 2, soon falling. Stamens 6 in 2 groups, each with 1 whole and 2 half stamens. Gynoecium composed of 2 fused carpels. Inflorescence a short, 2–6(–8)-flowered raceme. Subtending bracts large, entire, ovate–obovate, quite blunt.
- Leaves: Alternate, stalked. Lowest stem leaf scaly, other (1–)2 leaves ternate–biternate, leaflets fairly round.
- Fruit: Resembling a siliqua, ovately lanceolate, flat, 15–20 mm (0.6–0.8 in.) long capsule.
- Habitat: Broad-leaved forests.
- Flowering time: (April–)May.
- Endangerment: Protected in the provinces of Oulu and Lapland.
Corydalis intermedia is a demanding fumewort species that grows mainly in broad-leaved forests and coppices on the Åland Islands, the archipelago and in Häme. It is a modest, delicate and low-growing species which easily goes unnoticed among forest litter, and often because the seeker has arrived too late. Corydalis intermedia is part of the group of feral herbs that flowers earliest in Finland – it has already bloomed by the beginning of May and only the underground root tubers remain over the summer. Before the aerial shoots wither, one or two bulbils with new tubers at their base develop in the tip of tubers in the basal leaves’ axils. These gradually develop their own rootstock and become independent from the aging, disintegrating tuber. If there are two tubers they separate from each other and both develop their own shoots independently. Corydalis intermedia regularly self-pollinates and the seeds mature quickly and land in the soil as the aerial parts of the plant wilt and disappear. In some years it can take over ten months for corydalis intermedia to show itself again.
Genus Corydalis plants used to be included in the Fumitory (Fumariaceae) family, which was recently downgraded to a Poppy family subgroup Fumarioidea. Corydalis intermedia and solid-tubered corydalis (C. solida) resemble each other, but the latter’s subtending bracts have lobed tips. Also, solid-tubered corydalis has significantly more flowers (10–20), while corydalis intermedia normally has 2–5, and 8 at the most. Solid-tubered corydalis is also less demanding and is clearly more common than corydalis intermedia.