Galeopsis tetrahit

Scientific Name Galeopsis tetrahit L.
Common Names English: Common Hempnettle; German: Gemeiner Hohlzahn; French: Galéopsis tétrahit; Spanish: Galeópside, Tetrahit
Description Annual, seed-propagated weed with taproot; up to 40 cm (15.74 inch) tall.

Descriptions

Characteristic Features

Swollen stem nodes, stems square in cross-section. Pink-to-bluish-purple flowers arising from the axils.

Cotyledons

Strong, smooth-edged, oval-stemmed, with two lobes at the base and a rounded tip.

Stems

Square in cross-section, with swollen stem nodes; simple or branched, rough owing to their stiff hairs.

Leaves

Long oval in shape, with downy hairs on both sides, with large regular teeth and reddish-brown stem.

Propagatio Organs

Flowers

Dense whorls of flowers in the axils, pink-to-bluish-purple.
Upper lip helmet-like, middle lobe of the lower lip almost square, with a yellow blotch, edged with purple, on the lower lip.

Flowering Period

July-October.

Fruit

Nutlets enclosed in the calyx.

Seeds

Oval, grayish-brown, with irregular, pale, warty blotches. Seeds germinate at a depth of 1-4 cm (0.39 - 1.57 inch) in early spring.

Viability Of Seeds

Up to 5 years.

Propagation

Approx. 200-2,000 per plant.

Occurrence

Habitat

Arable land, sometimes in woods, fens and wet heaths, waste ground, disturbed sites, railroads.

Soil

Fresh loams and sandy soils with a high nutrient (nitrogen) content.

Additional Crop Information

Summer cereals, row crops, gardens, fruit tree cultivation, vineyards.

Agricultural Importance

G. tetrahit is the most important member of the hempnettle family. It moderately reduces yield and interferes with combine harvesting.

Control

Integrated Crop Management

The soil surface should be cultivated in spring and autumn. Regular hoeing in spring will destroy most seedlings. Delayed crop drilling allows time for pre-sowing cultivations to kill the first flush of seedlings.

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