''Galeopsis tetrahit'', the common hemp-nettle or brittlestem hempnettle, is a
flowering plant in the family
Lamiaceae
The Lamiaceae ( )
or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...
, native to
Europe and northwestern
Asia.
It is a
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of t ...
annual plant
An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary according to geographical ...
growing to 1 m tall; it is a
pioneer species and thrives on disturbed sites or roadsides. The plant looks like
mint but is taller. The stems have reflexed hairs and swollen nodes. In cross section, the stem is square. The leaves are rhombic to elliptic, with coarsely to bluntly serrate edges. The flowers are multicoloured, with purple, pink, or white areas; diminutive, bilateral and snapdragon-like, and are mostly visited by
bumblebees.
The species is considered by some authorities to have arisen as a
natural hybrid between ''
Galeopsis pubescens'' and ''
Galeopsis speciosa''.
Description
Common hemp-nettle is an erect annual plant and grows to a height of about . The stem branches occasionally and is squarish and hairy, with glandular hairs on the upper part of the plant. The nodes are swollen and widely spaced and the pale green, stalked leaves are in opposite pairs. The leaf blades are hairy and are ovate with a long tapered tip and with regular large teeth on the margin. The
inflorescence forms a terminal spike and is composed of whorls of pinkish flowers with dark markings on the lower lip. The calyx has five sharp-pointed lobes and the corolla forms a two-lipped flower about long with a fused tube. The upper lip of each flower is convex with dense, glandular hairs and the lower lip is three-lobed, the central lobe being the largest, squarish with a flat or rounded edge. There are four stamens, two long and two short, the
gynoecium has two fused carpels and the fruit is a four-chambered
schizocarp. The plant has a slightly unpleasant smell.
Distribution and habitat
Common hemp-nettle is native to Europe and northwestern Asia. Its typical habitat is rough ground, arable land, logging clearances and waste places. It spreads readily as its sharp calyces adhere to clothing and animal pelts.
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References
Flora Europaea: ''Galeopsis tetrahit''
Plants for a Future: ''Galeopsis tetrahit''
{{Taxonbar, from=Q157684
tetrahit
Plants described in 1753
Flora of Europe
Flora of Asia
Medicinal plants
Taxa named by Carl Linnaeus