A few weeks ago we were plant-spotting around the small town of Lesmahagow in South Lanarkshire, walking across a dampish long-abandoned field. I believe this field was part of a once-glorious estate in the days of the Industrial Revolution when the area was mined for coal and families became rich. I’d like to know more about the history of this place which has been described as a ‘water-meadow’ but I haven’t found any information so far. It lies beside the River Nethan, next to a ruined building and a ruined walled garden.
There came the cry ‘Butterfly Orchid’ and we converged on a single, quite distinctive white orchid. The second cry was ‘Let’s find more’ and we did. Quite many, perhaps 100 stalks of Platanthera chlorantha.
A rare sight, two orchid species together. Lesmahagow, July 2026. Left: Dactylorhiza fuchsii, the common spotted orchid, right: Platanthera chlorantha the Greater Butterfly-orchid. Image: John Grace.
Widely distributed across Britain and much of temperate Eurasia, Platanthera chlorantha the Greater Butterfly-orchid, is admired for its tall flowering spikes, delicate greenish-white blossoms and sweet nocturnal fragrance. We were fortunate to find it in full-flower. Although never among the commonest of orchids, it remains locally abundant in suitable habitats and considered to be an excellent indicator of long-established, unimproved grassland and woodland.
Platanthera chlorantha is easily confused with the closely related Lesser Butterfly-orchid (Platanthera bifolia). The two species appear similar from a distance; careful examination reveals a few distinguishing features (Cole and Waller 2020)1.
The most important diagnostic character is the position of the pollinia. In orchids there are parcels of pollen (‘pollinia’) rather than the usual individual grains found in other flowers. In Greater Butterfly-orchid the pollinia diverge markedly from one another, forming a broad V-shape when viewed from the front. In Lesser Butterfly-orchid they are close and nearly parallel. This difference reflects adaptation to different pollinators and is regarded as the most dependable identification feature. Other characters such as height and number of flowers are not so reliable1.
Greater Butterfly-orchid, showing arrangement of flowers on the stem. Image: Chris Jeffree.
Growth begins in spring as new shoots emerge from a tuber formed during the previous year. Leaves develop rapidly before the flowering stem elongates during late May and June. Flowering in Britain generally occurs from late May until July. The pollinators are large night-flying moths. As they drink the nectar, the pollinia stick to the moth’s eyes rather than its proboscis (a strange state-of-affairs). Following successful pollination, capsules mature during late summer. Each capsule contains many thousands of microscopic seeds. Like all orchids, these seeds possess virtually no food reserves and depend upon infection by compatible mycorrhizal fungi to germinate successfully, and a few years might pass before the plant emerges above the ground.
Greater Butterfly-orchid, showing flowers. Pollinia are visible on the central flower. Nectar spur (up to 3 cm long) can best be seen in the top left part of the picture. Image: Chris Jeffree.
Hybrids can be formed between the two species. Studies in the Netherlands and Sweden (cited in Stace et al. 2016) show that the hybrids can be formed rather easily and they are fertile. However, in the wild the structure of the flower is adapted for pollination by different species of moth, hence cross pollination is unusual. The two species have somewhat different soil requirements (Stace et al. 2016): P. chloranther has a preference for well-drained and somewhat calcareous soils whereas P. bifolia is more acid-loving. Their separation is further ensured by their fragrances: they emit difference scents to attract their own preferred species of moth2.
Orchids do sometimes occur in urban settings. In the Urban Flora project P. chloranther was found three times on Skye (Broadford and Portree), once in Dumbuch (Dumbartonshire) and once in Bearsden.
A remarkable image showing a night-flying moth on Butterfly orchid. According to the title on wikipedia this is the pine hawk-moth (Sphinx pinastri) and its proboscis measures ‘approximately 29.6 mm to 31 mm’. Attribution: Kārlis Kalviškis, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
More often, the sites are not urban. Browsing the BSBI data base for P. chloranther (643 Scottish records since 2020) we find many are distinctly out-of-town. They include place-names that stir the hearts of true Scots: Glencoe and Culloden Battlefield, but also several golf courses and an airfield. Orchids of course spend much of their time below the ground, making a brief appearance for pollination. Human affairs and the goings-on above the soil are of no concern unless they are disturbed.
The butterfly orchid gets its name from the shape of the flowers, which look like butterflies. The Latin name is from from Ancient Greek meaning ‘broad anther with green flowers’.
Distribution of Platanthera chlorantha in Britain and Ireland. From BSBI/Maps.
Notes
1. Summary of differences, as revealed in Darwin’s landmark 1862 book, On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects.
| Feature | Platanthera bifolia (Lesser) | Platanthera chlorantha (Greater) |
|---|---|---|
| Pollinia Structure | Close together and parallel (“II” shape). | Widely spaced and divergent (“V” shape). |
| Anther Position | Narrowly separated. | Widely separated. |
| Moth Attachment Site | Proboscis (tongue). | Compound eyes. |
| Nectar Spur | Slender and shorter. | Thicker and slightly longer. |
2. The long spur of this orchid is a reservoir of sugar-rich nectar, which only moths with the longest proboscis can reach.
References
Bateman RM, Stott KM and Pearce DF (2023) Trait analysis in a population of the Greater Butterfly-orchid observed through a 16-year period. Front. Plant Sci. 14:1213250. doi: 10.3389/fpls.2023.1213250
Durka W et al. (2017). Darwin’s legacy in Platanthera: are there more than two species in the Platanthera bifolia/chlorantha group?. Plant systematics and evolution, 303(3), 419-431.
Mõtlep, M et al. (2026), Differences in reproductive performance traits of two Platanthera species. Nordic Journal of Botany, 2026: e03854. https://doi.org/10.1002/njb.03854
Proctor M, Yeo P and Lack A (1996)The Natural Histroy of Pollination. Collins.
Nilsson LA (1983). Processes of isolation and introgressive interplay between Platanthera bifolia (L.) Rich and P. chlorantha (Custer) Reichb.(Orchidaceae). Botanical Journal of the Linnean Society, 87(4), 325-350.
Proctor M, Yeo P and Lack A (1996)The Natural Histroy of Pollination. Collins.
Stpiczyńska, M. (2003). Nectar resorption in the spur of Platanthera chlorantha Custer (Rchb.) Orchidaceae – structural and microautoradiographic study. Plant Syst Evol 238, 119–126.
Stace CA, Preston CD and Pearman DA (2016) Hybrid Flora of the British Isles. BSBI.
©John Grace
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