Weed Seed: Eriochloa villosa (Woolly cup grass)

Invasive Plant - Woolly cup grass (Eriochloa villosa)

Family

Poaceae

Common name

Woolly cup grass

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.

Listed on the List of Pests Regulated by Canada established under the Plant Protection Act.

Distribution

Canadian: Limited populations are under official control in QC.

Worldwide: Native to temperate and subtropical parts of eastern Asia. Reported to be introduced beyond its native range in the Caucasus region, western Siberia, southern Asia and Iran. Also introduced to the Ukraine, France and the United States (Darbyshire et al. 2003Footnote 1). Well-established in the mid-western states (CFIA 2014Footnote 2).

Duration of life cycle

Annual

Seed or fruit type

Spikelet

Identification features

Size

  • Spikelet length: 3.9 – 6.2 mm
  • Spikelet width: 2.0 – 3.2 mm

Shape

  • Ovate-shaped spikelet with a pointed tip, compressed dorsiventrally

Surface texture

  • Glumes and sterile floret of spikelet are smooth and leathery; fertile floret is hard with a grid pattern

Colour

  • The spikelet is straw yellow, often with purple streaks; floret is straw yellow

Other features

  • Ring of hardened tissue at the base of the spikelet

Habitat and crop association

Cultivated fields, open grassy places, hillsides, roadsides, along fences and ditches, and wastelands (CFIA 2012Footnote 3, 2014Footnote 2). A problematic weed in corn and soybeans in the United States (CFIA 2014Footnote 2).

General information

Woolly cup grass was accidentally introduced into the United States in the 1940s (Owen 1990Footnote 4). In the midwestern United States, where it interferes with corn and soybean crops, it has proven difficult to control with pre-emergence herbicides because it germinates throughout the growing season (Owen 1990Footnote 4).

This species has also appeared in climatic zones outside of the Midwest in places such as California and Pennsylvania, suggesting that the species can adapt to many climatic conditions (Darbyshire et al. 2003Footnote 1).

Similar species

Field paspalum (Paspalum laeve)

  • The two species are a similar size, straw-yellow colour, oval shape, and flattened cross-section.
  • Field paspalum spikelets have humped profiles, papery glumes and no purple streaks, while woolly cup grass spikelets are flattened in profile; have leathery glumes and purple streaks. Field paspalum does not have a ring of tissue at the base of its spikelet.

Photos

Woolly cupgrass (Eriochloa villosa) spikelets, florets and caryopses
Woolly cupgrass (Eriochloa villosa) spikelet
Woolly cupgrass (Eriochloa villosa) spikelet, side view
Woolly cupgrass (Eriochloa villosa) spikelet base with ring of hardened tissue
Woolly cupgrass (Eriochloa villosa) floret with inner bracts
Woolly cupgrass (Eriochloa villosa) caryopsis

Similar species

Similar species: Field paspalum (Paspalum laeve) spikelet
Similar species: Field paspalum (Paspalum laeve) floret, profile
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