- Latin synonyms: Dactylorhiza viride, Dactylorhiza viridis
- Name also: Longbract Frog Orchid, Long-bracted Green Orchid
- Family: Orchid Family – Orchidaceae
- Growing form: Perennial herb. Root tubers deeply lobed.
- Height: 10–30 cm (4–12 in.).
- Flower: Perianth irregular (zygomorphic), lime green–reddish brown, approx. 1–1.5 cm (0.4–0.6 in.) wide. Tepals 6, in 2 whorls, upper outside tepal helmet-like, one inner tepal elaborated into labellum. Labellum under perianth, spurred, lime green, narrow, tip 3-lobed, central lobe short. Spur very short, pouch-like. Androecium and gynoecium fused into a column, stamens 1, stigmas 2. Inflorescence a quite lax, 5–20-flowered spike. Subtending bracts large.
- Leaves: Alternate, stalkless, 3–5, usually 3, becoming smaller towards crown, ascending oblique. Lowest blades obovate, upper lanceolate, parallel-veined, with entire margin, green on top, underside grayish green.
- Fruit: Capsule, seeds tiny, like dust.
- Habitat: Broad-leaved forests, grove-like forests, meadow patches, moist meadows, rich swamps, roadside ditches, grove-like mountain birch woodland, rich fellside moors and meadows.
- Flowering time: June–August.
- Endangerment: Near threatened.
Frog orchid’s flowers are modest in appearance and also have a weak fragrance. It was initially thought that they do not interest pollinators at all, until a Finnish botanist decided to watch the plants during the night as well: in the wee small hours of the morning there was a lot of buzzing around as soft-shelled genus Cantharis blister beetles looked for nectar in the flower. It was also visited by hymenopterans, mosquitos and gnats, of which ichneumonoids in particular could well be the main pollinators alongside the beetles. It is possible that the flower only secretes nectar in the early morning, thus limiting its potential pollinators to a very select group. An abundant flow of nectar is good for insects that are active during the day, but these can take precious pollen to any old flower as they move around – it’s better to be satisfied with a smaller group that don’t really visit other flowers.
Frog orchid is a strongly mycotrophic species which greatly exploits its symbiotic relationship with fungus. The plant can look quite different depending on which part of Finland it is growing in – in the south it is large and greenish while in the north it is smaller, with smaller flowers which often have a more reddish brown colour. Possibly the variation in appearance and redness is because of environmental factors, in which case they would have no bearing on classification. Frog orchid used to have a genus of its own but is so close to genus Dactylorhiza that they are nowadays regarded as one. The fact that they are such close relations can be seen in the way that frog orchid sometimes breeds with heath spotted orchid (D. maculata ssp. fuchsii) and Lapland marsh orchid (D. lapponica).