Ontario Weeds: Common burdock
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Flowers and Fruit
- Habitat
- Similar Species
- Related Links
Name: Common burdock, Arctium minus
(Hill) Bernh.,
Other Names: petite bardane, Burdock,
Burs, Clotbur, Lesser burdock, Wild burdock, Wild rhubarb, bardane
mineure, rapace, rhubarbe sauvage, toques
Family: Composite or Aster Family (Compositae)
General Description: Biennial, reproducing
only by seed.
Photos and Pictures
Burdock, first-year rosette. |
Burdock, second-year plant beginning to flower. |
Common burdock. A. Rosette of leaves. |
B. End of flowering branch. |
Stems & Roots: Stems erect, 60-180cm
(2-6ft) high, often widely branched, thick, hollow, grooved lengthwise;
first leaves in a basal rosette, becoming large (up to 50cm, 20in.
long, and 30cm, 12in. wide), with heart-shaped base, coarse, resembling
a clump of cultivated rhubarb, but the undersides of the leaf blades
are white woolly and the stout leafstalks are hollow; lower leaves
on the stem of second-year plants similar to basal leaves, smaller,
alternate (1 per node); middle and upper leaves gradually smaller
with shorter, slender stalks and the blade tending to be less heart-shaped
and more pointed towards both ends, especially among the flower
heads.
Flowers & Fruit: Flower heads
globular, numerous, borne singly on short stalks or in small clusters
at ends of branches and from axils of leaves; each head about 2cm
(4/5in.) in diameter, densely covered with purplish, hooked bristles;
ray florets absent; disk florets purple or occasionally white, closely
packed in the centre of the head; at maturity the head or bur (hence
the common name "burdock") easily breaks off its stalk
and clings to clothing and animal fur, gradually scattering the
brownish angular seeds, each about 6mm (1/4in.) long. Flowers from
July to September.
Habitat: Common burdock occurs throughout
Ontario in waste places, pastures, open woods, roadsides, fencerows
and barnyards but seldom in cultivated land.
Similar Species: It is distinguished by
its rosette of very large heart-shaped leaves resembling Rhubarb
but woolly on the undersurface and with hollow leafstalks, and its
tall, branched stem in the second year with many short-stalked flower
heads or burs densely covered with hooked spines and borne singly
or in small clusters at ends of stems and from leaf axils, these
turning brown at maturity.
Related Links
... on general Weed
topics
... on weed identification, order OMAFRA
Publication 505: Ontario Weeds
... on weed control, order OMAFRA
Publication 75: Guide To Weed Control
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