Sherardia arvensis

Morphological description

Small annual herbaceous plant, generally 5 to 20 cm tall, but can also reach up to 40 cm. The habit is prostrate or ascending, with thin, slender stems, branched from the base and quadrangular to the touch. The surface of the stems is rough, with curved aculeate hairs that make them scabrous to the touch, especially along the edges.

The leaves are arranged in whorls, 4 in the lower part, 6 in the upper part, with a spiral arrangement along the stem. They are lanceolate, small in size (about 2-8 mm long and 1-5 mm wide), with scabrous and mucronate margins, that is ending with a sharp point or a short spine. The leaf is uninerved, tapered towards the base and often with ciliolate margins.

The flowers are gathered in terminal or axillary inflorescences, formed by small few-flowered heads (from 2 to 10 flowers), surrounded and often exceeded by an involucre composed of 6-10 lanceolate bracts, arranged in a star shape, scabrous along the margins and fused at the base. The flowers are tetramerous, with a hypocrateriform corolla (funnel-shaped with expanded edges), predominantly pink-lilac in color, although sometimes white-flowered specimens can be found. The corolla measures about 4-5 mm, with a cylindrical tube about 1.5 times the lobes (3-4 mm tube and 1-1.5 mm lobes). Four stamens are present with filaments inserted on the corolla tube.

The calyx is persistent and enlarging in the fruit, with 4-6 subulate and triangular teeth 0.3-1 mm long, bristly and rough due to short hairs. The fruit is a bilocular schizocarp 2-5 mm long, composed of two mericarps fused at the base and each crowned by three persistent and bristly calyx teeth. The root system consists of a thin and slender root.

Habitat and distribution

The species is widely distributed throughout the Italian territory, present in almost all regions and altitudes up to about 1900 m a.s.l. It preferably grows in open and ruderal environments, such as cultivated fields, uncultivated lands, pastures, garrigues, path edges, vineyards and grassy places. It is frequently considered a weed in agricultural crops due to its ability to adapt to different soils, generally well-drained and sunny.

In the Mediterranean basin it is present in almost the entire area, from southern Europe to western Asia up to North Africa, especially in temperate and Mediterranean climate zones. It prefers sunny exposures and fresh but well-aerated soils, with a certain hardiness that allows it to rapidly colonize disturbed habitats.

Flowering period

Flowering extends from March to July, with possible extensions up to September in some Mediterranean areas or under favorable climatic conditions. The long duration of the flowering period allows the plant to complete the annual life cycle in a wide range of environmental conditions. In Italy the flowering peak generally occurs in late spring.

Ecology and pollination

Sherardia arvensis is an annual plant with a rapid life cycle, adapted to colonize temporary or disturbed environments. The hermaphrodite flowers, small and gathered in terminal heads, attract various pollinating insects, particularly small hymenopterans and dipterans, which favor pollination. The corolla with an elongated and lobed tube is structured to facilitate access to nectar by insects with suitable mouthparts.

Seed dispersal occurs through schizocarps that separate into two mericarps, favoring mechanical dissemination and potentially accidental transport by animals or agricultural machinery. The presence of bristly hairs on the fruit can facilitate adhesion to the hairs or fur of animals, contributing to dispersal.

Curiosities and traditional uses

In the past, the thin roots of this plant were used to extract a red pigment, employed in fabric dyeing. However, the limited yield and the less intense color compared to that obtained from Rubia tinctorum (madder) prevented the development of large-scale commercial cultivation. There are no established medicinal or food uses, nor significant references in Italian folklore, although the common name “toccamano” suggests a popular tradition linked to touch or manual use of the plant, perhaps due to its rough surface.

Etymology

The genus name, Sherardia, is a tribute to William Sherard (1659-1728), an English botanist from Oxford, student of Tournefort and Hermann. The specific epithet arvensis derives from the Latin arvum, meaning “field”, indicating the typical habitat of the species, that is cultivated or open lands.

The Italian common name “toccamano” seems to refer to the tactile sensation caused by the roughness of the stems and leaves, a distinctive characteristic of the plant, but its historical origin is not precisely documented.

Sources

• Prof. S. Pignatti, Flora d’Italia
• Acta Plantarum – Flora delle regioni italiane (scheda di Anja Michelucci)
• Tela Botanica / H. Coste, Flore descriptive et illustrée de la France
• World Flora Online (WFO)