Spiranthes spiralis

Morphological description

Perennial herbaceous plant belonging to the Orchidaceae family, it has an erect and slender habit, with a height ranging from 5 to 30 cm. The root system consists of 3-4 fusiform, deep and tuberous rhizotubers, which serve as storage organs for the plant. The stem is thin, covered with dense hairs especially in the upper part, while at the base it takes on a reddish coloration; it does not bear true leaves but is covered by bracteiform sheaths.

The true leaves are arranged in a basal rosette, with an ovate-elliptical shape. During the flowering period, however, the visible leaves belong to the plant that will flower the following year and are destined to disappear with the appearance of the new stem.

The inflorescence is a long raceme of small white-greenish flowers, arranged according to a characteristic spiral that wraps around the stem, from which the genus name derives. The tepals are connivent and forward-facing in a hood shape, about 4 to 6 mm long, with a greenish exterior. The labellum is oblong, concave at the base, with a crenulate and fringed margin on the sides, directed downwards and joined to the tepals forming a tube; it is white with a greenish or yellowish base. The bracts, hairy, are similar to or slightly shorter than the ovary, which is also fusiform and hairy.

The fruit is an ovoid fissure-dehiscent capsule with three ribs, containing numerous minute seeds, typical of orchids, which are mainly dispersed by the wind.

Habitat and distribution

The species is mainly widespread in Mediterranean and Atlantic regions, with extensive penetration into the European hinterland up to the Caucasus. In Italy it is present from sea level up to about 1000 meters altitude, in environments such as poor and dry meadows, whether mown or uncultivated, at the edge of thermophilous woods, paths and pine forests. It prefers well-drained soils, often calcareous, and exposure conditions ranging from sunny to partially shaded.

Flowering period

Flowering occurs in autumn, generally from September to November, making this species the last orchid of the year in many areas. No particularly significant geographical variations in the flowering period are known.

Ecology and pollination

The flowers, small but fragrant, attract pollinating insects that facilitate pollination. The spiral arrangement of the flowers on the inflorescence favors effective visits by pollinating insects. The species adopts a reproductive strategy that combines the production of numerous minute seeds, dispersed by the wind, with the ability to perennialize thanks to the rhizotubers, thus ensuring survival even in variable environmental conditions.

Curiosities and traditional uses

No particular ethnobotanical applications, medicinal or traditional food uses are known for this species. However, its presence is reported as an indicator of poor meadows and valuable semi-natural environments, and for this reason it is protected in some Italian regions, including Lombardy and Emilia-Romagna, where collection is regulated or prohibited to preserve wild populations.

Etymology

The genus name derives from ancient Greek: "speira" means spiral and "anthos" flower, recalling the characteristic spiral arrangement of the flowers on the inflorescence. The specific epithet "spiralis" reiterates this spiral conformation. The common Italian name "viticcini autunnali" refers to the twining tendril-like shape and the late flowering period, which coincides with autumn.

Sources

• Acta Plantarum - Flora delle regioni italiane (actaplantarum.org)
• Acta Plantarum - Flora delle regioni italiane (scheda di Marinella Zepigi)
• World Flora Online (WFO)