Autumn Ladies' Tresses

Autumn lady's tresses is a polycarp, perennial, herbaceous plant that remains underground during its dormancy in summer with tubers. The species has thirty chromosomes (2n=30).

Root. Underground there are two to four (or exceptionally six), egg-shaped or ovate-oblong, hard tubers which are usually 1–3 cm (0.39–1.18 in) long and ¾–1½ cm (0.3–0.59 in) in diameter, slightly tapering towards the tip. They are pale brown and smooth with short transparent hairs on the outside. These tubers, as in many orchids, have an earthy musty smell, originating from the mycorrhiza. There are no thick filamentous secondary roots as in many other orchids.

Stem. The plant needs many years to grow large enough (eight years) to produce above-ground parts, and to produce a flowering stalk (another three years). Even then, it mostly flowers once every few years, and will during hard times not surface at all. The stem is greyish green, usually 7–20 cm (2.8–7.9 in) (in Southern Europe exceptionally 40 cm) high, unbranched, erect, and terete. Especially further up, the stem is covered with short transparent glandular hairs. Below the flowers stand three to seven grayish green, acute leaves that envelop the stem, with membranous edges and three to five veins. Sometimes the withered leaf remains of the rosette of the previous year are still visible at the base of the stem.

Leaf. …

Autumn lady's tresses occurs in Europe and small adjacent parts of North Africa and Asia. In the west, it occurs from Ireland to Portugal, in the south from Spain including the Balearic Islands, the coastal mountains of Algeria, Italy including Sicily, Greece including Crete, the Mediterranean, Aegean and Black Sea Coasts of Turkey and the Caucasus Mountains, North Iran eastwards to the Western Himalayas. To the North its limit is from northern England, the Netherlands, Denmark and the southern Baltic, Poland to western Ukraine. It is now considered regionally extinct in Denmark, but it has been introduced to the Swedish island of Öland, where it now seems to be established. In Switzerland the most recent locations are around Lake Lucerne, the Rhine Valley near Chur, in the area of Lake Walen and in Ticino. In Italy it is found in the north-east near the sea. In Great Britain and Ireland its northernmost occurrence is on the Isle of Man. It has never been found in Scotland. In Ireland it has a scattered southern distribution north to County Sligo, with the only known colony in Northern Ireland discovered in 2023 in County Down. …

Autumn lady's tresses may be found on quite different substrates, from weathered chalk and limestone to sand and gravel in dunes and slightly acidic heathlands. Occasionally, it has also been found on clay on sloping sites. It sometimes occurs in lawns, and was reported from the top of a wall in Sicily. Soils need to be low in nitrogen and phosphorus and neither dry nor wet. The species occurs in different plant communities, most commonly in highly diverse Festuca ovina–Avenula pratensis grasslands that exist because of intense grazing by sheep or rabbits. These grasslands contain grasses, dicots, and mosses in different mixtures. The turf is short, continuous and consist of very small individual plants. Characteristic species that may be abundant in these grasslands in the UK include the grasses Sheep's fescue Festuca ovina, red fescue F. rubra, Quaking-grass Briza media, crested hair-grass Koeleria macrantha and Crested dog's-tail Cynosurus cristatus, the dicots ribwort plantain Plantago lanceolata, Small burnet Poterium sanguisorba ssp. …

The botanical name is derived from the ancient Greek σπεῖρα (speira) "spiral" and ἄνθος (anthos) "flower". The species name spiralis also refers to the placement of the flowers in a spiral.