Ontario
Weeds: Hemp-nettle
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Flowers and Fruit
- Habitat
- Similar Species
- Related Links
Name: Hemp-nettle, Galeopsis tetrahit
L.,
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.
Photos and Pictures
Hemp-nettle. A. Base of plant.
B. Portion of stem with 2 flowering branches.
C. Flower.
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.
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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