green foxtail weed

Green Foxtail (A) — Setaria viridis — Family: Poaceae — Grass

Green foxtail is a clumping annual grass that commonly invades Michigan turfs. Young plants can be difficult to distinguish from other grasses like crabgrass. Green foxtail produces a characteristic ‘foxtail’-like seedhead.

Other weeds in the Grass (Poaceae) family:

Green foxtail is a clumping annual grass that commonly invades Michigan turfs. Young plants can be difficult to distinguish from other grasses like crabgrass. Green foxtail produces a characteristic ‘foxtail’-like seedhead.

Also Known As.

  • bottle-grass
  • wild millet
  • pigeon-grass
  • leaves rolled in the bud
  • ligule a fringe of hairs
  • collar narrow, hairy
  • auricles absent
  • sheaths slightly compressed, hairy along the edges
  • blades soft, flat, narrow at the base, slightly more than 1/4 inch wide, sharp-pointed

The foxtails, in general, can be confused with crabgrass as seedlings. Giant foxtail (rarely in turf) is easily distinguished by conspicuous hairs on the upper leaf surface and sheath. Yellow foxtail lacks hairs on the sheath and is very sparsely hairy on the upper leaf surface but has long hairs at the base of the leaf. Green foxtail has sheaths with hairy margins but lacks hairs on the upper leaf surface.

The most effective management of foxtail is to maintain a dense turfgrass sward. As a summer annual, seeds will germinate in the spring when soil temperatures and moisture are optimum. Foxtail can produces thousands of seeds per year. Minimizing seed production with consistent mowing can be an effective long-term deterrent. Taller mowing heights and judicious nitrogen fertilization can be very effective to reduce foxtail populations.

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Ontario Weeds: Green foxtail

Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents
  1. Name
  2. Other Names
  3. Family
  4. General Description
    • Photos and Pictures
  5. Stems and Roots
  6. Flowers and Fruit
  7. Habitat
  8. Similar Species
  9. Related Links

Name: Green foxtail, Setaria viridis (L.) Beauv.,

Other Names: sétaire verte, Bottle brush, Bottle grass, Bristle grass, Foxtail millet, Millet, Pigeon grass, Wild millet, mil sauvage

Family: Grass Family (Gramineae)

General Description: Annual, reproducing only by seed.

Photos and Pictures

Green foxtail (A – plants; B – leaf-base with hairy ligule and ciliate margins of leaf sheath).

Green foxtail. A. Plant with stem folded twice. B. Leaf bse. C. Spike. Bristly foxtail. D. Leaf-base. E. Spike. F. Cluster of 3 spikelets and 6 bristles with backward-pointing barbs.

Stem and leaf-base characteristics of a typical grass.

Stems & Roots: Stems erect or spreading, 10-100cm (4-40in.) tall or occasionally taller, usually round in cross-section but occasionally much flattened; leaves and leaf sheaths of very young plants often densely hairy but with upward-pointing hair; upper leaf blades and leaf sheaths mostly without hair; margins and both surfaces of leaf blades rough with very fine forward-pointing barbs; leaf sheath split with overlapping margins, both margins being fringed with a band of short hair; ligule a fringe of hair 1.5-2mm (1/16-1/12in.) long; no auricles.

Flowers & Fruit: Inflorescence a very dense spike 1-15cm (2/5-6in.) long and 0.6-2.0cm (1/4-4/5in.) wide, usually straight and erect or rarely somewhat curved, the larger ones sometimes with short branches up to 1cm (2/5in.) long, and covered with short green to slightly purplish bristles which give the inflorescence a bottle-brush appearance; the bristles have microscopic forward-pointing barbs that allow the seed head to be dragged downwards but not pushed upwards over the skin or a rough surface. Spikelets about 2mm (1/12in.) long by 1mm (1/25in.) wide; each contains a single fertile floret (“seed” or “grain”), that is rounded on one surface but flattened on the other, finely cross-ridged (seen only with magnification), and dull yellowish-green with brownish spots. Flowers from July to August.

Habitat: Green foxtail is very common and widespread throughout all agricultural regions of Ontario. It grows well in all soil textures and occurs in cultivated lands, waste places, roadsides, gardens and occasionally lawns.

Similar Species: It is distinguished from Yellow foxtail by its green or purple bristles, the absence of long, kinky hair on the upper surface of the leaf blade near the stem, the presence of a fringe of hair on both margins of the leaf sheath, and its somewhat smaller grains or seeds. It is distinguished from Bristly foxtail by its denser, more continuous spike whose bristles do not cling when sliding the fingers upwards on it. It is distinguished from Giant foxtail by its usually shorter stature, its shorter, thinner and usually erect inflorescence (rarely curved or nodding) and the absence of a covering of short hair on leaf surfaces in the middle and upper parts of the plant.

Related Links

. on general Weed topics
. on weed identification, order OMAFRA Publication 505: Ontario Weeds
. on weed control, order OMAFRA Publication 75: Guide To Weed Control