Epilobium hirsutum

Morphological description

Perennial herbaceous plant, the Great Willowherb is characterized by an erect habit, with a height ranging from 50 cm up to 2.5 meters. The stem is robust, often branched in the upper part, and typically has a quadrangular section at the base, while it becomes more rounded at the top. The stem surface is densely covered with long, spreading hairs, sometimes mixed with smaller glandular hairs, giving it a hairy and velvety appearance.

The leaves are arranged mainly oppositely on the lower parts of the stem, while above they alternate and assume a semi-clasping position, partially embracing the stem. They are lanceolate or ovate-lanceolate, measuring between 1.5-2 cm in width and 4-12 cm in length, with an irregularly toothed margin and an acute apex pointing forward. The leaf surface is slightly velvety, covered with simple and glandular hairs, with well-visible secondary veins.

The inflorescence consists of wide and loose clusters, composed of 8-20 hermaphrodite, erect, and pedunculated flowers. The flowers are relatively large, with bilobed petals measuring from 6 to 20 mm long and 6-15 mm wide, of intense purplish pink color, often described as fuchsia. The sepals, green and mucronate, measure about 6-10 mm in length. The stamens are eight, erect, while the stigma is deeply divided into four lobes arranged in a cross, initially erect and later curved.

The fruit is a linear and pubescent capsule, which can reach lengths between 5 and 10 cm. The seeds are small (about 1 mm), oblong-obovoid, with a papillose surface and equipped with a tuft of woolly hairs (coma) 5-7 mm long, which facilitates wind dispersal. The root system includes a stoloniferous rhizome, often superficial, which allows the plant to expand horizontally and survive adverse conditions.

Habitat and distribution

The Great Willowherb is a common and widely distributed species throughout the Italian territory and the Mediterranean basin. It prefers humid and cool environments, such as ditch edges, marshes, reed beds, riverbanks, ponds, and generally wet places. It develops on soils of various types, provided they are sufficiently moist, and can grow from the plains up to about 1700 meters of altitude.

In Italy it is present in all regions, from the plains to hilly and mountainous areas, showing good adaptability. In the Mediterranean and much of Europe, it is mainly found in riparian and wet habitats, but it is also present in other areas with similar conditions. The plant prefers sunny or partially shaded exposures, where soil moisture is constant.

Flowering period

Flowering generally extends from July to September, with some local variation related to climate and altitude. In more temperate and humid climates, flowering can begin as early as June, while at altitude or in cooler conditions it lasts until September. The flowers are fragrant and last several days, favoring the attraction of pollinating insects.

Ecology and pollination

The species is an important melliferous resource for various insects, including bees and butterflies, which visit the flowers to collect nectar and pollen. The flower structure, with erect stamens and protruding stigma, facilitates entomophilous pollination. The plant reproduces both sexually, through seeds dispersed by the woolly coma and wind, and vegetatively through the stoloniferous rhizome.

Adaptation to wet habitats and the rhizomatous root system allow it to quickly colonize marginal areas of water bodies and river courses, contributing to soil stabilization and the ecological balance of aquatic and marsh plant communities.

Curiosities and traditional uses

The Great Willowherb is known in popular tradition for its medicinal properties. Historically it has been used as an astringent and emmenagogue, and more recently preliminary studies have highlighted potential uses for prostate problems and in the prevention of some viral infections. For external use, the plant has been employed to treat dermatitis, mouth inflammations, pharyngitis, and superficial wounds.

The hairy tufts of the seeds, although not able to replace cotton, have been used to make lantern wicks, exploiting their slow combustion capacity. It is also a valuable melliferous plant, contributing to the production of quality honey.

It is important to emphasize that traditional medicinal uses are for informational purposes only and do not replace official medical treatments.

Etymology

The scientific name derives from Greek: "epi" means "above" and "lobos" indicates "lobe," referring to the position of the petals above the ovary. The specific epithet "hirsutum" refers to the plant's hairiness, particularly evident on the stem and leaves.

The Italian common name "epilobio maggiore" highlights the relatively large size of the flowers compared to other species of the genus, while "garofanino d’acqua" refers to the similarity of the flower color to that of the carnation and its typically aquatic habitat.

Sources

• Prof. S. Pignatti, "Flora d'Italia"
• Acta Plantarum - Flora delle regioni italiane (scheda di Giuliano Salvai)
• Tela Botanica / H. Coste, "Flore descriptive et illustrée de la France"
• World Flora Online (WFO)