Weed Seed: Silky bent-grass (Apera spica-venti)

Family

Poaceae

Synonyms

Agrostis spica-venti

Distribution in Canada

Found in ON

Duration of life cycle

Winter annual

Seed/Fruit type

Grain, enclosed by palea and lemma

Seed identification features

Size

  • floret length: 3.0–3.7 mm
  • awn length: 4.0–7.0 mm
  • width: 0.5 mm

Shape

  • in outline: elongated oval
  • in cross-section: elliptical

Surface texture

  • roughened, pebbled surface, like sandpaper
  • short, stiff hairs on back of lemma, from middle to tip

Colour

  • medium brown

Other structures

  • long, thin awn extends straight from tip
  • short, thin stalk (rachilla) on inner base of seed
  • tuft of long, white bristles at base of outer side (lemma)
  • grain is soft (will yield under pressure)

Similar species

Interrupted bent-grass (Apera interrupta)

  • found in BC, ON, and the northwestern United States
  • similar to silky bent-grass in shape, awn, tuft of hairs at base, roughened surface texture and short hairs at top of lemma
  • floret longer than silky bent-grass by 1.0–2.0 mm, with an awn up to 7.0 mm longer

Velvet bent-grass (Agrostis canina)

  • found in QC, NB, NS, PE, NL, and the northeastern United States
  • similar to silky bent-grass in shape, size, awn and rachilla
  • Longer than silky bent-grass by 1.0–2.0 mm
  • awn is not bent, surface is smooth, and colour is darker than silky bent-grass

Species Comparison Chart

Species Length Awn length Surface texture
silky bent-grass 3.0–3.7 mm 4.0–7.0 mm roughened
interrupted bent-grass 4.0–5.0 mm 4.0–14.0 mm roughened
velvet bent-grass 4.0–5.0 mm 1.0–3.0 mm smooth

Photos

Photo - Silky bent-grass (Apera spica-venti) seed (showing inner side)
Silky bent-grass (Apera spica-venti) seed (showing inner side)
Photo - Silky bent-grass (Apera spica-venti) seed (close-up of inner side [rachilla])
Silky bent-grass (Apera spica-venti) seed (close-up of inner side [rachilla])
Photo - Silky bent-grass (Apera spica-venti) seed (showing outer side [lemma])
Silky bent-grass (Apera spica-venti) seed (showing outer side [lemma])
Photo - Silky bent-grass (Apera spica-venti) seeds
Silky bent-grass (Apera spica-venti) seeds

Similar species

Photo - Interrupted bent-grass (Apera interrupta) seed (showing inner side)
Similar species: Interrupted bent-grass (Apera interrupta) seed (showing inner side)
Photo - Interrupted bent-grass (Apera interrupta) seed (showing outer side)
Similar species: Interrupted bent-grass (Apera interrupta) seed (showing outer side)
Photo - Velvet bent-grass (Agrostis canina) seed (showing inner side)
Similar species: Velvet bent-grass (Agrostis canina) seed (showing inner side)
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