- Latin synonym: Listera cordata
- Name also: Heartleaf Twayblade (USA)
- Family: Orchid Family – Orchidaceae
- Growing form: Perennial herb. Rootstock horizontal.
- Height: 10–20 cm (4–8 in.). Stem unbranched.
- Flower: Perianth irregular (zygomorphic), greenish–brownish–reddish, approx. 0.5 cm (0.2 in.) wide. Tepals 6 in 2 whorls, of which one elaborated into labellum. Labellum under perianth, spurless, tip deeply 2-lobed. Androecium and gynoecium fused into a column, stamens 1, stigmas 2. Inflorescence a short, lax, 3–14-flowered raceme.
- Leaves: 2 opposite on lower half of stem, stalkless, amplexicaul. Blade widely cordate, with entire margins, parallel-veined, shiny on top, underside greyish green.
- Fruit: Almost spherical, yellowish, quite erect capsule. Seeds minute, dust-like.
- Habitat: Coniferous forests, stream banks, peat-covered areas, bog margins.
- Flowering time: June–August.
Although lesser twayblade is quite common it is small and inconspicuously greenish, and it challenges the botanist to push their powers of observation to the limit. It is a little easier if you know where to look: the likeliest places in southern Finland are fir bogs where blueberries grow, while in the north its habitat is a little drier, and also a little richer. Lesser twayblade rarely grows alone, so if one is found it implies the existence of others nearby. Its habit of growing in patches is due to the way it propagates itself vegetatively: thin creeping runners in the moss develop an adventitious bud, from which grows a new plant, which sends out another runner, and so on.
Lesser twayblade’s flowers are – like its pollinators (fungus gnats and dark-winged fungus gnats) – very small. Fungus gnats collect nectar to survive, not to feed their offspring. Although they are less industrious than e.g. bees, they make up for it with their large numbers, longevity, and the fact that they like the same habitat as lesser twayblade. A closer look at lesser twayblade’s flowers reveals their beautiful shades of green, brown and dark red; its fragrance on the other hand is unpleasant to the human nose, and is reminiscent of rotting food. The groove in the flower’s labellum holds a lot of nectar in relation to the small size of the plant. Most of the flowers develop capsules, although the change can be difficult to observe. Its good seed production is unfortunately of no real use if its habitat is disappearing. The species demands a consistently damp micro-climate, so clear-cutting and drainage ditches are destructive to them. It has become a lot harder to find as large parts of its traditional habitat have disappeared – at least for now. As is so typical of the Orchid family they can appear out of nowhere, if only the forest is allowed to grow old enough.