Ontario Weeds: Hemp-nettle
Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Other Names
- General Description
- Stems and Roots
- Flowers and Fruit
- Similar Species
- Related Links
Name: Hemp-nettle, Galeopsis tetrahit
Other Names: ortie royale, Bee nettle, Dog nettle, Flowering nettle, chardonnet, galéopside à tige carrées
Family: Mint Family (Labiatae)
General Description: Annual, reproducing only by seed.
Hemp-nettle. A. Base of plant.
B. Portion of stem with 2 flowering branches.
Stems & Roots: Stems erect, 30-80cm
(12-32in.) high, branched, square, usually swollen at the nodes,
covered with rather harsh, straight, long, somewhat downward-pointing
hair; leaves opposite (2 per node), ovate to elliptic with stretched-out
tips, stalked, sparsely hairy, margins with rounded teeth, veins
mostly ending in notches between the teeth.
Flowers & Fruit: Flowers in dense clusters in the axils of leaves near the ends of stems and branches; calyx short, tubular, 10-ribbed, ending in 5 equal, narrow, sharp, spine-like teeth about 5mm (1/5in.) long; these very spiny when mature; corolla pinkish to light purplish or whitish, often variegated, and usually with 2 yellow spots, 12-23mm (½-7/8in.) long, of 5 united petals, irregular, tubular, 2-lipped at the end, the upper lip 2-lobed, lower lip 3-lobed, each flower producing 4 egg-shaped nutlets ("seeds"), narrowed and somewhat triangular towards the basal end, about 3mm (1/8in.) long and grayish-brown. Flowers from mid-July to mid-August.
Habitat: Hemp-nettle occurs throughout Ontario, especially in central and northern areas, forming dense stands in grainfields and also present in seeded pastures, gardens, waste areas and along roadsides.
Similar Species: It is distinguished by being an annual with erect square stems covered with harsh downward-pointing hair frequently with a prominent swelling below each node, opposite leaves with stretched-out tips, leaf margins with rounded teeth, and dense clusters of pinkish or light purplish flowers with slender, sharp calyx lobes which become hard and very spiny at maturity.
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