Weed Seed: Bothriochloa laguroides (Silver beardgrass)

Family

Poaceae

Common Name

Silver beardgrass

Regulation

Prohibited Noxious, Class 1 in the Canadian Weed Seeds Order, 2016 under the Seeds Act. All imported and domestic seed must be free of Prohibited Noxious weed seeds.

Distribution

Canadian: Absent from Canada (Brouillet et al. 2016Footnote 1)

Worldwide: Native to North and South America, from the central United States to Argentina and Chile (USDA-ARS 2016Footnote 2).

Duration of life cycle

Perennial

Seed or fruit type

Spikelet

Identification features

Size

  • Spikelet length: 3.5 - 4.0 mm
  • Spikelet width: 1.5 - 1.7 mm
  • Awn length: up to 12.0 mm

Shape

  • Spikelet is long oval shape with 2 pedicels from the base

Surface Texture

  • Spikelet is smooth and shiny with white hairs

Colour

  • Spikelet is pale yellow

Other Features

  • A pair of pedicels extend ¾ up the ventral side of the spikelet.
  • Pedicels may have sterile spikelets attached.
  • Copious white hairs around the base of and along the margins of the spikelet and the pedicels.
  • Short teeth along the upper margins of the dorsal side of the spikelet.

Habitat and Crop Association

Field edges, pastures, grasslands, woodlands, river bottoms, and roadsides, on well-drained soils and often on limestone (Barkworth et al. 2003Footnote 3). Reported as a weed in alfalfa, beans and corn in Mexico (Hanan Alipi and Mondragón Pichardo 2009Footnote 4).

General Information

Silver beardgrass has been used in landscaping in the United States (Barkworth et al. 2003Footnote 3).

Similar species

Yellow bluestem (Bothriochloa ischaemum)

  • Yellow bluestem is a similar size, oval shape, yellow colour and smooth surface as silver beardgrass.
  • Yellow bluestem spikelets on average are 4.5 mm long and 1.0 mm wide, approximately 1.0 mm longer than silver beardgrass.
  • The teeth on the back of yellow bluestem bracts are larger, and the hairs at the tips of the pedicels are 3.0 mm shorter than silver beardgrass.
  • The dorsal side of silver beardgrass spikelets is smooth and pale; yellow bluestem spikelets are furrowed with purple tips.

Photos

Silver beardgrass (Bothriochloa laguroides) spikelets
Silver beardgrass (Bothriochloa laguroides) spikelets
Silver beardgrass (Bothriochloa laguroides) spikelet, exterior
Silver beardgrass (Bothriochloa laguroides) spikelet, outer side
Silver beardgrass (Bothriochloa laguroides) spikelet, interior
Silver beardgrass (Bothriochloa laguroides) spikelet, inner side
Silver beardgrass (Bothriochloa laguroides) spikelet
Silver beardgrass (Bothriochloa laguroides) spikelet
Silver beardgrass (Bothriochloa laguroides) spikelet outer bract showing short teeth along edge
Silver beardgrass (Bothriochloa laguroides) spikelet outer bract showing short teeth along edge

Similar species

Similar species: Yellow bluestem (Bothriochloa ischaemum) spikelets
Similar species: Yellow bluestem (Bothriochloa ischaemum) spikelets
Similar species: Yellow bluestem (Bothriochloa ischaemum) spikelet, showing teeth along sides of bract
Similar species: Yellow bluestem (Bothriochloa ischaemum) spikelet, showing teeth along sides of bract
Date modified: