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

Similar species