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Lesser Burdock

Arctium minus

  • Name also: Burweed, Louse-bur, Common Burdock, Button-bur, Cuckoo-button, Wild Rhubarb
  • Family: Daisy Family – Compositae, subfamily Carduoideae
    (formerly Aster Family – Asteraceae)
  • Growing form: Biennial herb. Strong-rooted.
  • Height: 50–100 cm (20–40 in.). Stem branching, rough, short-haired.
  • Flower: Single flower-like approx. 1.5–2.5 cm (0.6–1 in.) capitula surrounded by involucral bracts. Capitula ray-florets lacking, disc florets reddish violet, tubular. Stamens 5. Pistil of 2 fused carpels. Involucre virtually spherical, woolly when young, becoming glabrous. Involucral bracts overlapping in many rows, long, branched, narrowly lanceolate, rigid, usually with orange hooked tips. Capitula a racemose cluster, branches straight, pedicels 0–4 cm (0–1.6 in.) long.
  • Leaves: Alternate, stalked. Blade broadly lanceolate–ovate, cordate-based, often large-toothed, underside white-greenish-cottony.
  • Fruit: Oval, virtually straight, brown, black-flecked achene, tip with short, yellow barbed down.
  • Habitat: Yards, farms, sometimes roadsides, heaps of earth in urban areas, wasteland.
  • Flowering time: July–September.

Lesser burdock thrives best among people, often growing behind cow byres or against the walls of outdoor buildings. Its habitat in Finland is close to its natural habitat, but it is hard to say if it arrived under its own steam or if it only arrived with people. Before people began to affect the environment, species that like open areas did not have much room to manoeuvre among the coniferous forest. Suitable habitats were mainly comprised of peatland meadows, the shores and banks of waterways, and fell tundra, and perhaps mammoths, cattle and other large mammals that lived in Finland after the Ice Age also played a part in keeping areas of land open. We know very little, however, about the meadow plants that existed in these times when the ancestors of the Finns cleared the first fields in the forest and sent the cattle out to graze for the first time on natural pasture. It is likely that several southern European meadow species would have appeared with the arrival of cattle and cultivated seed – and native plants spread on their own to clearings in the forest.

Burdocks are quite difficult to tell apart, and they can also cross-breed with each other. Lesser burdock can be differentiated from common woolly burdock (A. tomentosum) by the form of the inflorescence: the latter’s capitula are grouped together in a corymbose bunch of equal length, while lesser burdock’s capitula are in a racemose group. Additionally, lesser burdock’s capitulum becomes glabrous later on, not densely woolly like woolly burdock’s. Lesser burdock only grows to half the size of woolly burdock. Woolly burdock is a more rural plant with no apparent wish to forge a niche for itself in densely populated areas, so given the way the modern world is moving it is no surprise that it has become rarer over the last 20 years. Lesser burdock and wood burdock (A. nemorosum), which look very alike, can grow in the same places. The easiest way to tell them apart is that the latter is generally much larger.

Other species from the same genus
Other species from the same family

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