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Panicum capillare L.

Overview
General Information
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Family :

Famille :

Poaceae

Synonym(s) :

Synonyme(s) :

Chasea capillaris (L.) Nieuwl. (POWO 2024)
Leptoloma capillaris (L.) Smyth (POWO 2024)
Milium capillare (L.) Moench (POWO 2024)
Leptoloma barbipulvinata (Nash ex Rydb.) Smyth (POWO 2024)
Milium barbipulvinatum (Nash ex Rydb.) Lunell (POWO 2024)
Panicum acutifolium Willd. ex Spreng. (POWO 2024)
Panicum barbipulvinatum Nash ex Rydb. (POWO 2024; USDA-ARS 2024; USDA-NRCS 2024)
Panicum barbipulvinatum var. hirsutipes Suksd. (POWO 2024)
Panicum bobartii Lam. (POWO 2024)
Panicum capillare var. agreste Gatt. (POWO 2024; USDA-NRCS 2024)
Panicum capillare subsp. barbipulvinatum (Nash ex Rydb.) Tzvelev (POWO 2024; USDA-NRCS 2024)
Panicum capillare var. barbipulvinatum (Nash ex Rydb.) McGregor (POWO 2024; USDA-NRCS 2024)
Panicum capillare var. brevifolium Rydb. & Shear (ALA 2024; POWO 2024; USDA-NRCS 2024)
Panicum capillare L. var. capillare (ALA 2024; USDA-ARS 2024)
Panicum capillare var. occidentale Rydb. (ALA 2024; POWO 2024; USDA-ARS 2024; USDA-NRCS 2024)
Panicum capillare var. vulgare Scribn. (POWO 2024)
Panicum elegantulum Suksd. (POWO 2024)
Panicum riparium H. Scholz (POWO 2024)

Common Name(s) :

Nom(s) commun(s) :

Witchgrass

(English) (Barkworth et al. 2003; AOSA 2024; USDA-NRCS 2024)
Capillary panic grass (English) (Clements et al. 2004)
Common millet (English) (ALA 2024)
Common witch grass (English) (Clements et al. 2004)
Fool-hay (English) (Di Tomaso and Healy 2007; Neal et al. 2023)
Old witch grass (English) (Clements et al. 2004)
Ticklegrass (English) (DiTomaso and Healy 2007; Bryson and DeFelice 2009)
Tumble panic (English) (DiTomaso and Healy 2007)
Tumble panicgrass (English) (CABI 2024)
Tumblegrass (English) (Clements et al. 2004)
Tumbleweed grass (English) (DiTomaso and Healy 2007)
Witch grass (English) (Darbyshire 2003)
Witch panicgrass (English) (NPT 2024)
Witches-hair (English) (DiTomaso and Healy 2007)
Mount au cul (French) (Clements et al. 2004)
Mousseline (French) (Clements et al. 2004)
Panic capillaire (French) (Clements et al. 2004)
Capim-mimoso (Portuguese) (USDA-ARS 2024)
Pânico-capilare (Portuguese) (USDA-ARS 2024)

Witch grass (Panicum capillare) florets 

  • Witch grass (Panicum capillare) florets 

  • Witch grass (Panicum capillare) floret, palea view

  • Witch grass (Panicum capillare) floret, lemma view

  • Witch grass (Panicum capillare) florets and spikelet

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Overview

Aperçu

Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 4: Secondary Noxious Weed Seeds
  • CFIA Weed Seeds Order - Class 5: Noxious Weed Seeds

Regulation Notes:

Panicum capillare is listed as a Harmful Organism by Peru and the Republic of Korea (USDA-PCIT 2024).

Distribution :

Répartition :

Panicum capillare is a widespread native of southern Canada, the United States (excluding Alaska and Hawaii), northern Mexico, and some Caribbean Islands (Ickert-Bond et al. 2019; Gallaher et al. 2020; USDA-ARS 2024). It has been introduced to Argentina, Chile, Brazil, Uruguay, Japan, Russian Far East, New Caledonia, New Zealand, Pakistan, Caucasus Region, Turkey, Palestine, Lebanon-Syria, Canary Islands, Madeira, and throughout much of Europe (POWO 2024; WFO 2024).

Habitat and Crop Association :

Habitat et Cultures Associées :

Panicum capillare grows primarily in regions with a temperate climate (POWO 2024). In natural habitats, P. capillare grows in open areas of disturbed or eroded soils including beaches, floodplains, around springs (including thermal springs), and edges of alkali flats, but does not thrive in dense shade (Clements et al. 2004). In areas of human activity, P. capillare is found in cultivated fields, vineyards, gardens, lawns, turf, pastures, abandoned agricultural fields, along roadsides, railways, irrigation ditches, canal, pond and reservoir banks (Clements et al. 2004; DiTomaso and Healy 2007; Bryson and DeFelice 2009).

P. capillare is a common weedy pest in agronomic, horticultural, and nursery crops (Neal et al. 2023). It is a common weed in Glycine max (L.) Merr. (soybean), Sorghum bicolor (L.) Moench (sorghum), Triticum aestivum L. subsp. aestivum (common wheat), and Zea mays L. (corn) (Clements et al. 2004). The spread of this species in Europe may be attributed to seed lot contamination in cereal grains, Phleum pratense L. (timothy), and Trifolium L. spp. (clovers) (Clements et al. 2004).

Economic Use, cultivation area, and Weed Association :

Utilisation économique, zone de culture et association de mauvaises herbes :

Duration of Life Cycle :

Durée du cycle vital:

Annual

Dispersal Unit Type :

Type d’unité de dispersion :

Spikelet, floret

General Information

RENSEIGNEMENTS GÉNÉRAUX

Panicum capillare is a summer annual that is a desirable component of its natural plant communities in North America as the foliage and seeds are an important food source for many species of gamebirds, songbirds, and mammals (Clements et al. 2004; DiTomaso and Healy 2007). P. capillare is a prolific seed producer capable of producing more than 11,000 seeds per plant (Stevens 1932). At maturity the seeds may fall from the plant but usually the entire inflorescence breaks away from the plant and tumbles along the ground dispersing the seeds (Clements et al. 2004). Seeds can further be dispersed by water, as seed lot contaminants, or by animals. Seeds are reported to remain viable after passing through digestive tracts of horses, sheep, swine, and cattle (Muenscher 1955).

Ethnobotanical studies from the first half of the twentieth century describe uses for P. capillare by North American Native Peoples (NAEB 2003). The Navajo used seeds of P. capillare for food and the plants as fodder for sheep and horses. The Hopi ground seeds of P. capillare to make bread and to mix with cornmeal. The Mahuna used infusions of the plant as a dietary aid. The Tewa used P. capillare plant fiber to make brooms and to clean grinding stones.

Panicum capillare has become a weedy pest in agricultural fields, grasslands, gardens, lawns, and turf in North America and in countries where it has been introduced. Although it appears P. capillare can be controlled by most standard herbicide treatments, there are reports of triazine-resistant P. capillare biotypes in croplands of Ontario Canada and along railroad beds in the northeastern United States from New York to Michigan (Clements et al. 2004; Heap 2024).

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Identification

Identification

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  • Spikelet

    Size

    • Spikelet length*: 2.3 – 2.7 mm (average 2.5 mm); width*: 0.9 – 1.2 mm (average 1.1 mm)
    • Lower (1st) glume length*: 1.1 – 1.4 mm (average 1.2 mm).
    • Upper (2nd) glume length*: 2.3 – 2.6 mm (average 2.5 mm).
    *Note: minimum and maximum based on a random selection of 14 spikelets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements by D. J. Lionakis Meyer.

    Measurements from the literature:
    • Spikelet length: 2.5 – 3.2 (3.5) mm; upper (2nd) glume length: 2 – 2.8 (3.4) mm (Cronquist et al. 1977).
    • Upper (2nd) glume length: (2) 2.5 – 3.5 (4.5) mm long (Clements et al. 2004).

    Shape

    • Spikelet teardrop-shaped (lanceolate), widest near midpoint or lower, dorsoventrally compressed.
    • Lower (1st) glume broadly triangular, the tip tapering to a wide or sharp point, the outer corners wrapping around the base of the upper (2nd) glume.
    • Upper (2nd) glume teardrop-shaped (lanceolate).

    Surface Texture

    • Glumes thin and papery.
    • Lower (1st) glume 3 – 5 nerved; upper (2nd) glume 5 – 7 nerved.
    • Nerves with short stiff hairs near the tips.

    Colour

    • Glumes pale green to brownish-yellow, often with purple tinge.

    Other Features

    • The spikelet contains one sterile floret (lower) and one fertile floret (upper).
    • Spikelet disarticulation usually occurs below the fertile floret allowing the fertile floret to fall free from the plant, but may occur below the glumes, with the spikelet falling as a unit from the plant.

    Witch grass (Panicum capillare) florets and spikelet

  • Sterile floret

    Size

    • Sterile lemma slightly shorter or nearly equal to length of spikelet, exceeding the fertile floret.

    Shape

    • Sterile lemma tear-drop shaped (lanceolate), widest near midpoint or lower.

    Surface Texture

    • Sterile lemma thin and papery, similar looking to upper (2nd) glume, several nerved.
    • Nerves with short stiff hairs near tip.

    Colour

    • Sterile lemma pale green to brownish-yellow, often with purple tinge.

    Other Features

    • Sterile palea usually absent (Cronquist et al. 1977) or reduced to a ridge of tissue (Clements et al. 2004).

  • Floret (fertile)

    Size

    • Fertile floret length*: 1.6 – 1.8 mm (average 1.7 mm); width*: 0.8 – 1.1 mm (average 1.0 mm).
    • Fertile floret length**: 1.3 – 1.7 mm; width**: 0.7 – 0.8 mm.
    *Note: minimum and maximum based on a random selection of 20 florets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements D. J. Lionakis Meyer.
    **Note: minimum and maximum based on a random selection of 10 florets in a normal range of this species using image measurement protocol (ISMA 2020). Measurements by CFIA.

    Measurements from the literature:
    • Fertile lemma length: 1.5 – 2 mm (Cronquist et al. 1977).
    • Fertile floret length: (1.1) 1.2 – 2 mm (Clements et al. 2004).

    Shape

    • Fertile floret oval to oblong, dorsal-ventrally compressed, widest near midpoint.
    • Fertile lemma margins in-rolled over margins of palea.
    • Palea keels not concealed by the lemma.

    Surface Texture

    • Fertile lemma and palea hardened, smooth, glossy.

    Colour

    • Fertile lemma yellowish to greenish-brown with dark brown mottling, and 5 – 7 prominent light yellowish coloured longitudinal lines.
    • Fertile palea same color as lemma, keel nerves light yellowish coloured.

    Witch grass (Panicum capillare) florets 

  • Caryopsis

    Size

    • Caryopsis length*: 1.2 – 1.3 mm; width*: 0.8 mm
    • Hilum about one-quarter the length of caryopsis.
    *Note: minimum and maximum based on a random selection of 7 caryopses in a normal range of this species using image measurement protocol (ISMA 2020).

    Measurements from the literature:
    • Caryopsis about 1.5 mm long, about 1.0 mm wide (Walters 2011).

    Shape

    • Caryopsis oval, slightly narrowed near base of embryo.

    Surface Texture

    • Caryopsis surface smooth.

    Colour

    • Caryopsis body and embryo are light brownish-yellow coloured, the tip of caryopsis may be darker at the style base.
    • Hilum is dark brown in colour.

    Other Features

    • Hilum circular to oval, located near base of caryopsis.
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  • Embryo

    Size

    • Embryo is about one-half the length of caryopsis.

    Shape

    • Embryo oval shaped.

    Endosperm

    • Endosperm solid (Terrell 1971).

    Other Features

    • Embryo in the lateral position (Martin 1946).

Identification Tips

CONSEILS POUR L’IDENTIFICATION

  • The spikelet consists of two papery glumes and a sterile floret that completely enclose a fertile floret.
  • The fertile floret lemma and palea are smooth, glossy, hardened, and enclose the caryopsis.
  • The fertile lemma has several light yellowish-coloured longitudinal lines contrasting against the darker background colour of the lemma.
  • The point of floret attachment is inconspicuous.

Witch grass (Panicum capillare) florets and spikelet

Additional Botany Information

AUTRES RENSEIGNEMENTS BOTANIQUES

Flowers/Inflorescence

  • The inflorescence is an open panicle, 13 – 50 cm long and 7 – 24 cm wide, that is usually one-half or more the height of the plant (Barkworth et al. 2003).
  • At maturity, the entire panicle disarticulates near the base of the peduncle and the panicle becomes a tumbleweed, dispersing propagules as it rolls on the ground (Barkworth et al. 2003).

Vegetative Features

  • Plants densely tufted, 15 – 100 cm tall, stems erect, upright or decumbent at the base, rooting at the nodes, sometimes branching at lower nodes.
  • Leaf sheaths and blades covered with soft or bristly hairs, many with swollen bases, standing at right angles from the surface.
  • Leaf sheaths open with hairy, overlapping margins.
  • Auricles absent.
  • Ligule a fringe of hairs up to 2 mm long.
  • Leaf blades up to 25 cm long and 0.5 – 2 cm wide.
  • Root system shallow and fibrous.

Description based on Royer and Dickinson (1999), Clements et al. (2004) and DiTomaso and Healy (2007).

Similar Species

ESPÈCES SEMBLABLES

Similar species are based on a study of seed morphology of various species, and those with similar dispersal units are identified. The study is limited by physical specimen and literature availability at the time of examination, and possibly impacted by the subjectivity of the authors based on their knowledge and experience. Providing similar species information for seed identification is to make users aware of similarities that could possibly result in misidentification.

Panicum dichotomiflorum Michx.
Fall panicum (USDA-ARS 2024)

The fertile floret of P. dichotomiflorum is oblong and flattened, while in P. capillare the fertile floret is slightly convex on the lemma side and is oval-shaped. The scar at the base of the fertile floret is small and inconspicuous in both species (Musil 1963).

Panicum hillmanii Chase
[Panicum capillare subsp. hillmanii (Chase) Freckmann & Lelong] (USDA-ARS 2024)
Hillman’s panicum (USDA-ARS 2024)

Spikelets similar to P. capillare but the palea of the sterile floret is present, membranous, translucent, and about one-half the length of the sterile lemma (sterile palea usually absent in P. capillare). Fertile floret of P. hillmanii is broadly oval, the scar at base is prominent, crescent-shaped, 1 mm wide; whereas, in P. capillare the fertile floret is narrower, and the scar is small and inconspicuous (Musil 1963).

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Reference(s)

Référence(s)

Association of Official Seed Analysts (AOSA). 2024. AOSA Rules for Testing Seeds, Volume 3: Uniform Classification of Weed and Crop Seeds. Association of Official Seed Analysts, Wichita, Kansas, USA.

Atlas of Living Australia (ALA). 2024. Panicum capillare L., Common Millet. https://bie.ala.org.au/species/https://id.biodiversity.org.au/node/apni/2902904 Accessed November 5, 2024.

Barkworth, M. E., Capels, K. M., Long, S., and Piep, M. B. 2003. Flora of North America, Vol. 25 Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press.

Bryson, C. T. and DeFelice, M. S. (eds.). 2009. Weeds of the South. University of Georgia Press.

Centre for Agriculture and Bioscience International (CABI). 2024. Panicum capillare (tumble panicgrass). https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.38663#abstract Accessed November 5, 2024.

Clements, D. R., DiTommaso, A., Darbyshire, S. J., Cavers, P. B., Sartonov, A. S. 2004. The Biology of Canadian Weeds. 127. Panicum capillare L. Can. J. Plant Sci. 84:327-341.

Cronquist, A., Holmgren, A. H., Holmgren N. H., Reveal, J. L., Holmgren, P. K. 1977. Intermountain Flora: Vascular Plants of the Intermountain West, U.S.A. Volume 6: The Monocotyledons. Columbia University Press, New York NY.

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds Agriculture and Agri-Food Canada. 43.

DiTomaso, J. M. and Healy, E. A. 2007. Weeds of California and Other Western States. Volume 2 – Geraniaceae – Zygophyllaceae. Publication 3488. University of California.

Gallaher, T. J., Brock, K., Kennedy, B. H., Imada, C. T., Imada, K., Walvoord, N. 2020. Plants of Hawaiʻi. http://www.plantsofhawaii.org Accessed November 5, 2024.

Heap, I. 2024. The International Herbicide-Resistant Weed Database. www.weedscience.org Accessed November 6, 2024.

Ickert-Bond, S. M., Bennett, B., Carlson, M.L., DeLapp, J., Fulkerson, J. R., Parker, C. L., Nawrocki, T. W., Stensvold, M. C., and Webb, C. O. (eds.). 2019. Flora of Alaska. https://floraofalaska.org Accessed November 5, 2024.

International Seed Morphology Association (ISMA). 2020. Method for seed size measurement. Version 1.0. ISMA Publication Guide. https://www.idseed.org/authors/details/method_for_seed_size_measurement.html

Martin, A. C. 1946. The comparative internal morphology of seeds. The American Midland Naturalist 36(3):513-660.

Muenscher, W. C. 1955. Weeds. 2nd ed. Cornell University Press. Ithaca, NY.

Musil, A. F. 1963. Identification of Crop and Weed Seeds. Agriculture Handbook No. 219. U. S. Department of Agriculture, Agricultural Marketing Service, Washington D.C.

Native Plant Trust (NPT). 2024. Panicum capillare – witch panicgrass. https://gobotany.nativeplanttrust.org/species/panicum/capillare/ Accessed November 3, 2024.

Native American Ethnobotany Database (NAEB). 2003. Native American Ethnobotany: A Database of Foods, Drugs, Dyes, and Fibers of Native American Peoples, Derived from Plants. http://naeb.brit.org/ Accessed November 5, 2024.

Neal. J. C., Uva, R. H., DiTomaso, J. M., DiTommaso, A. 2023. Weeds of the Northeast. 2nd Ed. Cornell University Press.

Plants of the World Online (POWO). 2024. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. https://powo.science.kew.org/ Accessed October 29, 2024.

Royer, F. and Dickinson, R. 1999. Weeds of the Northern U.S. and Canada. University of Alberta Press and Lone Pine Publishing.

Stevens, O. A. 1932. The number and weight of seeds produced by plants. Am. J. Bot. 19:784-794.

Terrell, E. E. 1971. Survey of occurrences of liquid or soft endosperm in grass genera. Bull. Torr. Botan. Club 98(5):264-268.

United States Department of Agriculture-Agricultural Research Services (USDA-ARS). 2024. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch Accessed October 29, 2024.

United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2024. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. https://plants.usda.gov/home Accessed November 6, 2024.

United States Department of Agriculture – Phytosanitary Certificate Issuance and Tracking System (USDA-PCIT). 2024. https://pcit.aphis.usda.gov/PExD/faces/ViewPExD.jsf Accessed November 5, 2024.

Walters, D. S. 2011. Identification Tool to Weed Disseminules of California Central Valley Table Grape Production Areas. USDA APHIS PPQ CPHST Identification Technology Program, Fort Collins, CO. http://idtools.org/id/table_grape/weed-tool/ Accessed November 5, 2024.

World Flora Online (WFO). 2024. Panicum capillare L. http://www.worldfloraonline.org/taxon/wfo-0000883399. Accessed November 5, 2024.

 

Author(s)

AUTEUR(S)

Deborah J. Lionakis Meyer, California Department of Food and Agriculture (retired).

Acknowledgments

The author wishes to thank the following from the Canadian Food Inspection Agency (CFIA): reviewer Jennifer Neudorf for her suggestions for fact sheet improvement.

contactus@idseed.org

Last updated
on 2023-03-27

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