Weed Seed: Sweet vernal grass (Anthoxanthum odoratum)

Family

Poaceae

Distribution in Canada

Found in YT, BC, ON, QC, NB, NS, PE, NL

Duration of life cycle

Perennial

Seed/Fruit type

  • grain, enclosed by a palea and lemma
  • floret may be enclosed in sterile florets with awns (long bristles)

Seed identification features

Size

  • floret length: 2.0 mm
  • floret width: 1.0 mm
  • enclosed floret length: 3.0–3.5 mm
  • enclosed floret width: 1.0–1.2 mm
  • awn length: 5.0–9.0 mm

Shape

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

Surface texture

  • enclosing (sterile) floret surface is papery and slightly roughened like sandpaper
  • short, stiff hairs surround base and cover enclosing floret, obscuring surface
  • (fertile) floret has a smooth, glossy surface, and is slightly 2-lobed at top

Colour

  • medium reddish-brown, becoming pale at tip

Other structures

  • long, bent awn extends straight from tip of 2 papery, sterile florets surrounding fertile, plump floret

Similar species

Annual vernal grass (Anthoxanthum aristatum)

  • found only in BC
  • similar to sweet vernal grass in size, elliptical shape, reddish-brown colour, bent awn-tipped enclosing florets, and dense bristles
  • florets are similar to sweet vernal grass; plants are easily distinguishable by their duration and vegetative features
  • florets are slightly (~0.5 mm) smaller than sweet vernal grass
  • hairs are in vertical lines (outer, sterile, florets of sweet vernal grass are densely covered by stiff hairs)

Photos

Photo - Sweet vernal grass (Anthoxanthum odoratum) floret group 1
Sweet vernal grass (Anthoxanthum odoratum) floret group 1
Photo - Sweet vernal grass (Anthoxanthum odoratum) floret group 2
Sweet vernal grass (Anthoxanthum odoratum) floret group 2
Photo - Sweet vernal grass (Anthoxanthum odoratum) floret groups
Sweet vernal grass (Anthoxanthum odoratum) floret groups

Similar species

Photo - Annual vernal grass (Anthoxanthum aristatum) floret group
Similar species: Annual vernal grass (Anthoxanthum aristatum) floret group
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