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. 2016^Footnote 1)

Worldwide: Native to North and South America, from the central United States to Argentina and Chile (USDA-ARS 2016^Footnote 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. 2003^Footnote 3). Reported as a weed in alfalfa, beans and corn in Mexico (Hanan Alipi and Mondragón Pichardo 2009^Footnote 4).

General Information

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

Similar species