Ontario Weeds: Motherwort
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Flowers and Fruit
- Habitat
- Similar Species
- Related Links
Name: Motherwort, Leonurus cardiaca
L.,
Other Names: agripaume cardiaque, agripaume,
herbe piquante
Family: Mint Family (Labiatae)
General Description: Perennial, reproducing
only by seed.
Photos and Pictures
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Motherwort. A. Top of plant before flowers open.
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B. Mature calyx with its 5 slender, spiny-tipped lobes.
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Stems & Roots: Stems erect, 40-180cm
(16-70in.) high, square, somewhat hairy along the angles, branched,
frequently several stems from 1 coarsely fibrous root crown; leaves
opposite (2 per node), lower ones long-stalked, rounded in outline,
palmately cleft into usually 5 or more main lobes which are coarsely
or irregularly toothed, upper leaves on shorter stalks, smaller, and
only 3- or 5-cleft.
Flowers & Fruit: Flowers in the axils
of small upper leaves; calyx tubular with 5 slender, sharp lobes,
3 pointing upwards and 2 downwards, becoming hard, sharp, and spiny
at maturity; the calyx breaking off and clinging as a bur to clothing
or fur; corolla pink to pale purple or whitish, upper lip conspicuously
white-hairy, not lobed, lower lip 3-lobed; each flower producing 4
nutlets ("seeds") which are triangular, dark brown and hairy
at the apex. Flowers from June to August
Habitat: Motherwort occurs throughout
southern Ontario in yards, waste places, fence lines, and roadsides.
Similar Species: It is distinguished in
non-flowering stages by its palmately lobed leaves (almost like maple
leaves) in geometrically precise arrangement in 4 vertical planes
around the square stem. Flowering and fruiting plants are distinguished
by their palmately lobed leaves, clusters of pinkish flowers in leaf
axils, and the calyx of each flower with 5 very sharp lobes, 3 pointing
upwards and 2 downwards, these becoming spiny bur-like clusters on
mature and dry stems.
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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