Greater Butterfly Orchid
- Written also: Greater Butterfly-orchid
- Family: Orchid Family – Orchidaceae
- Growing form: Perennial herb. Tubers unbranched.
- Height: 25–60 cm (10–25 in.).
- Flower: Irregular (zygomorphic), lime greenish, approx. 1–2 cm (0.4–0.8 in.) wide. Tepals 6, in 2 whorls, with one inner tepal elaborated into labellum and uppermost outer tepal helmet-shaped. Labellum under perianth, spurred, 10–16 mm (0.4–0.6 in.) long almost linear, narrow, lime greenish. Spur 18–27 mm (0.7–1.1 in.) long, becoming wider towards tip, quite blunt. Androecium and gynoecium fused into a column, stamens 1, pollinia some distance from each other, stigmas 2. Inflorescence a narrow conical spike. Flower lightly scented or scentless.
- Leaves: Basal leaves 2, almost opposite, stalked. Blade obovate–broadly elliptic, with entire margins, glabrous. Upper stalk with 1–3 alternate small, almost linear upper leaves.
- Fruit: Erect capsule, almost parallel to stalk.
- Habitat: Broad-leaved forests, coppices, pastures. Calciphile.
- Flowering time: June–July.
- Endangerment: Protected in all of Finland, except the Åland Islands.
Greater butterfly orchid and lesser butterfly orchid (P. bifolia) are very closely related species, and it is not always easy to tell them apart, although there are differences in their size, habitats and flowering times. The clearest markers are in the flower. Lesser butterfly orchid flowers are white, while greater butterfly orchid flowers are pale lime green – the species’ Swedish name, literally ‘pale green night pansy’, is very descriptive. Greater butterfly orchid only grows in Finland in the Åland Islands and on the south-west coast, while lesser butterfly orchid, which is not so demanding, appears on the mainland even quite far north.
Lesser butterfly orchid is well-known for its summer evening fragrance while greater butterfly orchid on the other hand is usually regarded as scentless, although certain people can distinguish its clear, if weak, fragrance. The difference is not in the amount of perfume but rather its quality. Lesser butterfly orchid’s pleasant, heady fragrance is mainly comprised of aromatic esters while greater butterfly orchid’s flowers contain mainly large-moleculed compounds that belong to the alcohol group. Aromatic esters attract primarily hawk moths, while alcohol is favoured by other moths. The structure of the flower is also tailored to suit certain pollinators: lesser butterfly orchid’s almost fused pollinia closely pinch the base of the hawk moth’s proboscis, while the greater butterfly orchid’s pollinia attach to the moth’s eyes and the distance between the pollinia is the same as the distance between the eyes of the most important pollinators. In order for the viscidia to definitely hit the right spot, the greater butterfly orchid must ensure that the insect pushes its head right against the flower and its nectar spur is a shade longer than the moth’s proboscis. Despite all the arrangements the same insects sometimes visit both flowers where the species grow side by side. Hybrids are created occasionally, but they are very rare. Unexpectedly, their markers are roughly intermediate forms of their parent plants’.