Arctium lappa

Morphological description

A large biennial herbaceous plant, Greater Burdock has an erect and robust habit, with a height ranging between 80 and 200 cm. The stem is grooved, often reddish, and branches in the apical part, sometimes covered by a light layer of silky tomentum. The base of the stem and the petioles of the basal leaves are filled with pith (not tubular), a distinctive characteristic compared to other similar species.

The leaves are large, alternate, with a blade that can reach remarkable dimensions, up to 50 cm long and 40 cm wide. They are ovate or heart-shaped, especially the basal ones, while the cauline leaves tend to be sessile and smaller, with decreasing size towards the apex. The upper surface of the leaves is bright green, glabrous, while the lower surface appears whitish and cobwebby, with a dense tomentose hairiness that gives a grayish appearance. The petioles are grooved and filled with pith.

The inflorescence consists of spherical capitula, 3-4 cm in diameter, gathered in terminal corymbs and borne on peduncles at least 2.5 cm long. Each capitulum is wrapped by acuminate, glabrous, entirely green bracts, with a hooked apex, which give the plant the characteristic ability to cling to animals and clothes. The flowers are tubular, hermaphroditic, violet or purplish in color, with a corolla about 1.4 cm long and a tube about 8 mm. The stamens and stigmas are glabrous, but with a tuft of hairs at the apex of the style.

The fruit is an oblong-elliptic achene, about 6-7 mm long, reddish-brown with black spots, wrinkled at the apex, surmounted by a pappus of yellowish ciliate bristles at the base and by a disc with a wavy and pleated edge.

The root system is characterized by a large taproot, fleshy, brown on the outside and white inside, which allows the plant to store nutrients during the first year of life, when the basal rosette develops.

Habitat and distribution

Greater Burdock is widespread almost everywhere in Italy and is present throughout temperate Europe and Asia, with a Eurasian range extending from the European continent to Japan. In Italy it commonly grows in ruderal environments, along roadsides, wastelands, forest clearings, and paths, from the lowlands up to about 1,800 meters altitude. It prefers well-drained soils, often disturbed or rich in nutrients, and adapts to sunny or partially shaded exposures.

In the Mediterranean it is mainly found in the more temperate regions, where anthropized environments and open woods offer favorable conditions for its growth.

Flowering period

Flowering occurs in the second year of the plant’s life, generally between July and September, with a higher concentration in July and August. In some geographical areas, especially at altitude or in cooler climates, flowering may undergo slight variations but remains concentrated in the summer season.

Ecology and pollination

Greater Burdock is an entomophilous species, mainly pollinated by pollinating insects such as bees and other hymenopterans that visit the numerous tubular flowers to collect nectar and pollen. The corymbose structure of the capitula favors the attraction of numerous insects simultaneously.

Seed dispersal occurs thanks to the pappus formed by hooked bracts, which easily attach to animal fur or clothing fabrics, facilitating the spread of the species over wide distances and in diverse environments.

Curiosities and traditional uses

Greater Burdock has played an important role in traditional medicine and popular culture of many civilizations. Its roots and leaves are known for their medicinal properties: they contain polyphenolic compounds, polysaccharides such as inulin, essential oils, tannins, lignans, and B vitamins.

It is traditionally used as a depurative, anti-inflammatory, antibacterial, diuretic, and hypoglycemic herb. In particular, the root is employed to treat dermatitis, eczema, psoriasis, acne, boils, and other skin conditions. Bardana extract is used both internally and externally, for example to stimulate hair growth.

In cooking, the petioles of young leaves are consumed boiled or fried, while the large fleshy root can be eaten raw in salad or cooked like carrots, also in frying.

Historically, Bardana has been used both in European folk medicine and in Asian medicine. For example, ancient Chinese doctors used it for colds and respiratory infections; in medieval Europe it was included in herbals and recommended for various diseases, although its therapeutic efficacy was later questioned by modern experts.

The plant also has a role in beekeeping, being a good source of nectar for honeybees.

Etymology

The genus name derives from the Greek “arktos” meaning “bear”, probably referring to the spiny infructescences and the rough appearance of plants of this genus, which recall the roughness of bear fur. The specific epithet “lappa” derives from the Latin “lappare”, meaning “to grasp”, referring to the ability of the infructescences to easily adhere to animals or clothes.

In Italian, the common name “Bardana” is traditional and widespread, while “Greater Burdock” distinguishes it from other species of the genus present in the territory.

Sources

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