Weed Seed: Common hemp-nettle (Galeopsis tetrahit)

Family

Lamiaceae

Distribution in Canada

Found in Canada

Duration of life cycle

Annual

Seed/Fruit type

  • nutlet - a 1-seeded dry fruit with thick shell
  • develop in groups of 4 nutlets

Seed identification features

Size

  • length: 2.5–3.0 mm
  • width: 2.0–2.5 mm

Shape

  • in outline: obovate (upside-down egg-shaped), with widest point above middle
  • in cross-section: lens-shaped

Surface texture

  • bubbled with random pattern
  • slight sheen overall

Colour

  • medium brown
  • bubbled areas are light brown, with occasional black spots

Other structures

  • hilum area is at base of seed (cut diagonally)
  • hilum area is dull and roughened

Similar species

Good reference material is needed to distinguish these 3 species.

Hairy hemp-nettle (Galeopsis pubescens)

  • native to Europe; not yet found in North America
  • similar to Common hemp-nettle in size, obovate shape, single diagonal hilum, and bubbled surface pattern with black spots
  • darker brown and oval shaped (not as narrowed at hilum end as Common hemp nettle)

Large-flowered hemp-nettle (Galeopsis speciosa)

  • found in AB, ON, QC
  • similar to Common hemp-nettle in size, obovate shape, single diagonal hilum, and bubbled surface pattern with black spots
  • darker brown colour than Common hemp-nettle
  • hilum end more strongly narrowed than Common hemp-nettle

Photos

Photo - Common hemp-nettle (Galeopsis tetrahit) seed (inner side with hilum at base)
Common hemp-nettle (Galeopsis tetrahit) seed (inner side with hilum at base)
Photo - Common hemp-nettle (Galeopsis tetrahit) seed (outer side)
Common hemp-nettle (Galeopsis tetrahit) seed (outer side)
Photo - Common hemp-nettle (Galeopsis tetrahit) seeds
Common hemp-nettle (Galeopsis tetrahit) seeds

Similar species

Photo - Similar species: Hairy hemp-nettle (Galeopsis pubescens) seeds (inner side [L], outer side [R])
Similar species: Hairy hemp-nettle (Galeopsis pubescens) seeds (inner side [L], outer side [R])
Photo - Similar species: Large-flowered hemp-nettle (Galeopsis speciosa) seeds (inner side [L], outer side [R])
Similar species: Large-flowered hemp-nettle (Galeopsis speciosa) seeds (inner side [L], outer side [R])
Date modified: