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Viola L. spp.

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General Information
ID Info
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Family :

Famille :

Violaceae

Synonym(s) :

Synonyme(s) :

Chrysion Spach (FNA 1993+)
Crocion Nieuwland & Kaczmarek (FNA 1993+)
Lophion Spach (FNA 1993+)
Erpetion Sweet (USDA-ARS 2024)
Mnemion Spach (USDA-ARS 2024)

Common Name(s) :

Nom(s) commun(s) :

Violet

(FNA 1993+; USDA-ARS 2024)

Field violet (Viola arvensis) seeds

  • Field violet (Viola arvensis) seeds

  • Field violet (Viola arvensis) seed

  • Field violet (Viola arvensis) seed

  • Viola odorata seeds

  • Viola odorata seeds,two views

  • Viola odorata seed, close-up of chalaza

  • Viola pubescens seeds

  • Viola pubescens seed

  • Viola pubescens seed

  • Viola sororia seeds

  • Viola sororia seeds

  • Viola sororia seeds, three views

  • Viola sororia seed, surface close-up

  • Wild pansy (Viola tricolor) seeds

  • Viola ×wittrockiana seed

  • Viola ×wittrockiana seeds

Explore More :

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Overview

Aperçu

Regulation :

Remarques Réglementation:

    Regulation Notes:

    Distribution :

    Répartition :

    Viola is native and widespread throughout every continent except Antarctica (POWO 2024). It is most abundant in temperate regions but also in warmer habitats in South America and the Pacific Islands (FNA 1993+), especially at higher elevations. There are approximately 400-600 species (FNA 1993+), or 664 species (Marcussen et al. 2020), or up to 994 when including accepted hybrids (GBIF 2019).

    In Canada, Viola is found throughout the southern provinces and northern territories with 41 native species, 4 introduced, 2 ephemeral in British Columbia, and another 3 reported but unconfirmed. Additionally, 13 native hybrid species are also reported, almost entirely found in southeastern Canada (Brouillet et al. 2010+).

    In the United States, Viola is found throughout the continental states, Alaska, and Hawaii, with 79 of 86 species found being native, including multiple narrow endemics of California (4), Hawaii (8), Utah (2), Washington (1), and Arizona (1). Only 5 species were introduced, and an additional 2 were reported but unconfirmed. There are also 42 named hybrids and 1 unnamed hybrid found throughout the continental states, 42 of which are native and almost exclusively found in the northeast, except 1 native hybrid found in Hawaii (USDA-NRCS 2024).

    Habitat and Crop Association :

    Habitat et Cultures Associées :

    Viola species occupy a wide range of habitats, from moist meadows and woods to bogs and dry prairies. A few Viola species are considered weedy, but they mostly grow in lawns and home gardens or sidewalk cracks (personal observation). Viola sororia Willd. is particularly notorious for its appearance in lawns (Nafici 2016) in the eastern USA and southeastern Canada, even though it is native there. Viola tricolor L. ssp. tricolor (Johnny jump-up) is non-native and fairly widely introduced all across North America (USDA-NRCS 2024).

    Viola arvensis L. is occasionally reported in cultivated fields, mostly in cereal crops but also in Glycine max (L.) Merr. (soybean) and Zea mays L. subsp. mays (corn), where it has been reported in Ontario, Canada (Government of Ontario 2024). Even still, it is not considered an overly competitive weed (Government of Ontario 2024).

    Economic Use, cultivation area, and Weed Association :

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

    Violets are mostly grown as ornamental flowers and to a lesser degree for their fragrance, with over 120 species grown worldwide (FNA 1993+) especially in the temperate world. Some common ones grown for the horticultural industry as ornamental flowers include Viola arvensis L. (field pansy), Viola tricolor (Johnny-jump-up), Viola × wittrockiana Gams ex Nauenburg & Buttler (common garden pansy), Viola odorata L. (sweet violet), and cultivars of V. sororia and Viola palmata L. (Marcussen et al. 2020).

    Since ancient times, the blue and purple-flowered species have been grown for use in sweets and jellies and the young leaves were boiled and eaten as vegetables (Gibbons 1972). Today, they are still popular with Viola gracilis Sm. (synonym Viola cornuta Desf.), Viola alba Besser (parma violet), Viola x hybrida Schur, Viola tricolor, Viola x williamsiana, Viola x wittrockiana (pansy) and Viola odorata all being grown as edibles, though only on small scales (Marcussen et al. 2020).

    Viola odorata (sweet violet) was widely cultivated commercially for use in the essential oil and perfume industry, although it has largely been replaced by synthetic compounds (Marcussen et al. 2020).

    Viola species have a long and widespread history of use by Native North American tribes. Several species were widely used medicinally for rheumatism, analgesic, pediatric, respiratory, gastrointestinal, gynecological, veterinary, heart, eye, dermatological aids and as an analgesic, tonic, emetic, and antidiarrheal as well as for colds and coughs (BRIT NAEB 2019).

    There has been a recent resurgence in interest in using Viola species medicinally. For instance, studies have shown that Viola odorata syrup helped to effectively control COVID-19 symptoms, including cough, myalgia, headache, and diarrhea (Mehraban et al. 2023). Other studies showed that Viola betonicifolia Sm. contained a beneficial profile of essential micro- and macronutrients, fats, protein, carbohydrates, and vitamin C when consumed as a food, and it was also well known for its use as an antioxidant, anthelminthic, antidepressant, anti-inflammatory, analgesic, and has been used to treat various neurological diseases (Rizwan et al. 2019).

    Duration of Life Cycle :

    Durée du cycle vital:

    Perennial, Annual

    Dispersal Unit Type :

    Type d’unité de dispersion :

    Seed

    General Information

    RENSEIGNEMENTS GÉNÉRAUX

    Viola species are generally weedy and tend to lack the usual barriers against hybridization, resulting in very large numbers of hybrids and difficult identification. Furthermore, speciation by allopolyploidization, the genome duplication in a hybrid, occurs in 67 to 88% of Viola species and has resulted in at least three major radiations within the genus (Marcussen et al. 2020), resulting in a large number of species.

    Since Viola is such a large genus, its taxonomy is an area of debate, at least in part due to the significant hybridization rates. For instance, there are 84 confirmed species in the US alone, with an additional 43 named hybrids (USDA-NRCS 2024). Another complicating factor in Viola taxonomy is the phenotypic variation seen in the genus, where the size of leaves and stems often increase substantially throughout the growing season and also vary with environmental factors like light, moisture, aspect, and other conditions (FNA 1993+). Perhaps these reasons can partly explain why the genus had not been revised since 1925 until very recently (Marcussen et al. 2020).

    Viola species invite a wide range of pollinators, including bumblebees, honeybees, solitary bees, syrphid flies, butterflies, skippers, hawkmoths, moths, bee flies, and possibly aphids and thrips (FNA 1993+) even though most sections of Northern Hemisphere Viola species exhibit seasonal cleistogamy, with normal flowers developing first, followed by cleistogamous flowers later in the season. Cleistogamy is a curious condition where permanently closed, self-pollinated flowers are formed and produce fruits without ever having opened to be cross-pollinated (Ammarellou et al. 2021).

    An estimated more than 70% of Viola seeds possess a small outgrowth known as a food body or elaiosome that makes them attractive to ants that carry the seeds to feed on the edible outgrowth, allowing the seeds to be dispersed in a process known as myrmecochory (FNA 1993+). Another interesting dispersal feature in the genus is that some species with thick capsules on erect peduncles (fruit stalks) as they dry they contract and squeeze, ejecting the seeds ballistically to aid in their dispersal (FNA 1993+).

    Violets have a long history in European folklore. They were first described in Ancient Greece, sold in the Athenian agora, recorded in poetry, used in medicine, and even played roles in myths like the abduction of Persephone. Their popularity continued throughout the Middle Ages, recorded in herbal books, painted in the Renaissance, and even associated with the Virgin Mary in Christianity (Marcussen et al. 2020).

    .

    Viola glabella plants in Peachland, BC, Canada – many Viola often spread as a groundcover via rhizomes or stolons (Lyrae Willis, Environmental Science Freelance Writer, lyraenatureblog.com)

    Identification

    Identification

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    • Capsule

      Size

      • Viola species capsule length range: 2.5-10 mm (FNA 1993+)

      Capsule size of selected species from FNA (1993+):

      • Viola arvensis Murray capsule length: 5– 9 mm
      • Viola odorata L. capsule length: 5 – 8 mm
      • Viola palustris L. capsule length: 6 -10 mm
      • Viola sororia Willd. capsule length: 5 – 12 mm
      • Viola tricolor L. capsule length: 6 – 8 mm

      Shape

      • Capsule spherical (e.g. V. arvensis), egg-shaped (e.g. V. tricolor, V. odorata), oval-shaped (e.g. V. canadensis L., V. palustris) or oblong (e.g. V. bicolor Pursh) (FNA 1993+)
      • Capsule end may be pointed (e.g. V. canadensis) or have a persistent style remnant (e.g. V. odorata)

      Surface Texture

      • Capsule surface smooth, with straight hairs (e.g. V. odorata, V. sororia ), dense, curled hairs (e.g. V. pubescens Ait.) or hairless (e.g. V. arvensis, V. tricolor) (FNA 1993+)

      Colour

      • Capsule is generally yellowish, light brown or brown (Doohan and Monaco 1992)
      • V. odorata capsules may be purple mottled (FNA 1993+)

      Other Features

      • Capsule has one chamber (locule) with the seeds attached to the inside wall (parietal) (Doohan and Monaco 1992)
      • Capsule splits in 3 wedge-shaped valves that fold lengthwise when mature, expelling the seeds from the plant (Doohan and Monaco 1992)

      Field violet (Viola arvensis) capsule (opened)

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    >

    • Seed

      Size

      • Viola species seed size range: length: 1.3 – 2.6 mm; width: 0.7 – 2.1 mm (Bojňanský and Fargašová 2007)

      Seed size of selected species from literature and image measurement:
      Viola arvensis Murray
      • Seed length: 1.6-1.8 mm; width: 0.8-1 mm (Bojňanský and Fargašová 2007)
      • Seed length*: 1.3 – 2.1 mm ; width: 0.7 – 1.0 mm (ISMA 2020)

      Viola kitaibeliana Schult.
      • Seed length: 1.38 ± 0.08 mm; width: 0.74 ± 0.05 mm (Scoppola and Magrini 2019)

      Viola odorata L.
      • Seed length**: 2.0 – 2.6 mm; width: 1.2 – 1.7 mm (ISMA 2020)
      • Seed aril covers 1/2-3/4 of the raphe, free portion at least 1/3 of the seed length (Bojňanský and Fargašová 2007)

      Viola palustris L.
      • Seed length: 1.4-1.7 mm; width: 0.9-1.1 mm (Bojňanský and Fargašová 2007)

      Viola sororia Willd.
      • Seed length: 1.5-2.5 mm (FNA 1993+)
      • Seed length*: 1.6 – 2.4 mm; width: 0.9 – 1.2 mm (ISMA 2020)

      Viola tricolor L.
      • Seed length: 1.4-1.7 mm; width: 0.7-0.9 mm (Bojňanský and Fargašová 2007)
      • Seed length*: 1.6 – 2.3 mm; width: 0.8 – 1.1 mm (ISMA 2020)

      Viola x wittrockiana Grams
      • Seed length: 2-2.3 mm; width: 1.1-1.3 mm (Bojňanský and Fargašová 2007)

      *Note: minimum and maximum of 20 seeds in a normal range of this species using image measurement (ISMA 2020)
      **Note: minimum and maximum of 10 seeds in a normal range of this species using image measurement (ISMA 2020)

      Shape

      • Seeds are generally egg-shaped with a narrow aril end, terete in 3 dimensions

      Surface Texture

      • Seed surface appears smooth, but is generally longitudinally wrinkled under 40x magnification with a reticulate pattern beneath
      • Some species have a granular or bubbled seed surface (e.g. V. biflora L., V. canina L., V. odorata, V. tricolor) (Bojňanský and Fargašová 2007)
      • The wider end opposite the aril has a round depression (chalazal area)
      • The aril and chalazal area are connected by a linear nerve (raphe)

      Colour

      • Seed colour is generally brownish (e.g. V. arvensis, V. tricolor, V. x wittrockiana), some species have yellowish seeds (e.g. V. odorata), or purplish-brown seeds (e.g. V. canadensis, V. palustris)
      • Seeds may have patches or mottles of dark brown, in species such as V. sororia, V. sagitatta Ait., and V. pedatifida G.Don (FNA 1993+), or brown stripes in V. biflora (Bojňanský and Fargašová 2007)
      • Seed raphe is generally brown or dark brown

      Other Features

      • Hilum is at the narrow end of the seed, covered with a white or light yellow, wrinkled and bubbled tissue outgrowth (an aril or elaiosome) that is generally partially removed after seed processing
      • V. arvensis seeds become sticky (mucilaginous) when wetted (Bojňanský and Fargašová 2007)
      • The wide (chalazal) end of the seed may have a dark brown, round spot (e.g. V. arvensis)

      Field violet (Viola arvensis) seeds

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    • Embryo

      Size

      • Embryo partially fills the seed

      Shape

      • Embryo is spatulate shaped (Martin 1946)

      Endosperm

      • Endosperm is soft, translucent white coloured

      Other Features

      • Embryo is in the axial position
      • Embryo not developed at time of dispersal (FNA 1993+)

    Identification Tips

    CONSEILS POUR L’IDENTIFICATION

    Seeds in the Violaceae generally have similar features (FNA 1993+):

    • Spherical or egg-shaped
    • Surface appears smooth
    • Glabrous surface
    • An aril at one end

    Seeds of Viola species can be distinguished by:

    • Generally small size (3 mm or smaller)
    • Conspicuous, wrinkled aril, covering the hilum and part of the raphe

    Field violet (Viola arvensis) seed

    Additional Botany Information

    AUTRES RENSEIGNEMENTS BOTANIQUES

    Flowers/Inflorescence

    • 1(–3) (rarely to 5)-flowered inflorescences found in leaf axils (FNA 1993+). Found in umbel-like clusters only in Viola sagittata Aiton. f. umbelliflora (FNA 1993+).
    • Inflorescences arise from stem nodes or from rhizomes or stolons in stemless species (FNA 1993+). Pedicels have two small bracts (WFO 2024).
    • Flowers are bisexual with bilateral symmetry, often having normal flowers (described below) followed by cleistogamous flowers later in the season (WFO 2024) which lack petals or have 2(3) immature petals and 2 stamens usually connected to the style (FNA 1993+).
    • Sepals entire, equal or subequal; margins often with prominent earlobe-like appendages (WFO 2024), with or without fine hairs (FNA 1993+).
    • Petals are showy and unequal; the largest anterior petal with a conspicuous pouch-like or elongated spur at its base (WFO 2024); upper (2) and lateral (2) petals are 5+ mm; lateral petals are bearded near the base and other petals may be bearded (FNA 1993+).
    • Style is bearded or beardless (FNA 1993+), usually curving downward but sometimes nearly erect; thickened or tapering towards the tip; style tip and stigma are variable (WFO 2024). The various shapes, sizes, hairs, and appendages on the style head are often used in Viola species classification (FNA 1993+).
    • Stamens with free with short filaments, often very closely packed and appearing joined and forming a sheath around the ovary; free from the style (except in cleistogamous); lower 2 filaments are spurred with nectaries that enter the petal spur (FNA 1993+; WFO 2024).

    Vegetative Features

    • Annual or perennial herbs (rarely subshrubs) with or without above-ground stems (FNA 1993+). Usually with one leaf form but variable in Viola palmata L. (lobed and unlobed), Viola sagittata, and Viola septemloba Leconte (FNA 1993+).
    • Stems simple 0–5(–10+); usually deciduous (rarely woody); erect to ascending or sprawling; from horizontal or vertical, narrow or thick, shallow or deep-seated rhizome or thin spreading stolons in perennials; from slender taproots in annual species (FNA 1993+).
    • Stemmed species sometimes have branched stems; leaves alternate with 0–11(–22) basal leaves per rhizome (FNA 1993+).
    • Stemless plants with 1–12(–18) leaves per rhizome on petioles that are prostrate to erect (FNA 1993+).
    • Leaves with stipules that may or may not be adhered to the petiole, not usually leaflike (sometimes in Viola lobata), unlobed and shorter than leaves (except Viola arvensis, Viola bicolor Pursh, and Viola tricolor) (FNA 1993+).
    • Leaves stalked and mostly simple; leaves compound in Viola beckwithii Torr., Viola douglasii Steud., Viola hallii A. Gray, Viola sheltonii Torr., and Viola trinervata (Howell) Howell ex A. Gray FNA 1993+).
    • Leaf blades not overlapping at the base (sometimes in Viola blanda Willd. and Viola rotundifolia Michx.); egg-shaped, kidney-shaped to heart-shaped, triangular, rounded, elongated teardrop, spoon-shaped, or linear; upper surface mottled only in Viola hastata Michx. and Viola hirsutula Brainerd (FNA 1993+).
    • Leaf margins entire, rounded-toothed (scalloped) or finely serrated.

    Viola glabella plant with flowers showing low growth form, mostly basal leaves, prostrate stems. Photo taken in Caren Range Mountains, BC, Canada (Lyrae Willis, Environmental Science Freelance Writer, lyraenatureblog.com)

    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.

    Hybanthus Jacq. species

    North American Hybanthus species may be larger than Viola species H. concolor (T. F. Forster) Spreng. seed length: (3–)4–7 mm, FNA 1993+), or a similar size, but dark brown, black and/or flattened or angular in 3 dimensions (FNA 1993+). South American species may have similar features as Viola species, and differing in the shape and size of the aril (Seo 2010).

    Euphorbia L. species

    The raphe, chalazal area and a tissue outgrowth at one end (caruncle) may look similar to Viola seeds. The caruncle of Euphorbia species is not as tightly attached and does not extend down the raphe as in Viola seeds.

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    Cliquez pour sélectionner les espèces

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    Reference(s)

    Référence(s)

    Ammarellou, A., Żabicka, J., Słomka, A., Bohdanowicz, J., Marcussen, T., & Kuta, E. 2021. Seasonal and Simultaneous Cleistogamy in Rostrate Violets (Viola, subsect. Rostratae, Violaceae). Plants, 10(10). https://doi.org/10.3390/plants10102147

    Bojňanský, V., and Fargašová, A. 2007. Atlas of Seeds and Fruits of Central and East-European Flora: The Carpathian Mountains Region. Springer, The Netherlands. 1046 pp.

    BRIT – NAEB. 2019. Native American Ethnobotany Database. Brit.org. http://naeb.brit.org

    Brouillet, L., Desmet, P., Coursol, F., Meades, S.J., Favreau, M., Anions, M., Bélisle, P., Gendreau, C., Shorthouse, D. 2010+. Database of Vascular Plants of Canada (VASCAN). Online at http://data.canadensys.net/vascan Accessed May 10, 2024.

    Doohan, D.J. and Monaco, T.J. 1992. The biology of Canadian weeds. 99. Viola arvensis Murr. Canadian Journal of Plant Sciences 72: 87-201.

    Flora of North America North of Mexico (FNA). 1993+. New York and Oxford, http://floranorthamerica.org/Main_Page Accessed May 10, 2024.

    Gibbons, E. 1972. Stalking the Healthful Herbs. David McKay Co. Philadelphia, PA, USA.

    Global Biodiversity Information Facility Secretariat (GBIF). 2024. https://www.gbif.org Accessed May 10, 2024.

    Government of Ontario. 2024. Field Violet | Weed identification guide for Ontario crops | ontario.ca. www.ontario.ca. https://www.ontario.ca/document/weed-identification-guide-ontario-crops/field-violet Accessed May 11, 2024.

    Heap, I. 2024. The International Herbicide-Resistant Weed Database. Online. www.weedscience.org Accessed May 10, 2024.

    International Seed Morphology Association (ISMA). 2020. Method for Seed Size Measurement. Version 1.0. ISMA Publication Guide.

    Marcussen, T., Ballard, H. E., Danihelka, J., Flores, A. R., Nicola, M. V., & Watson, J. M. 2022. A Revised Phylogenetic Classification for Viola (Violaceae). Plants, 11(17). https://doi.org/10.3390/plants11172224

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

    Mehraban, Adel, M. S., Shirzad, M., Taghizadeh Kashani, L. M., Ahmadian-Attari, M. M., Safari, A. A., Ansari, N., Hatami, H., & Kamalinejad, M. 2023. Efficacy and safety of add-on Viola odorata L. In the treatment of COVID-19: A randomized double-blind controlled trial. Journal of Ethnopharmacology, 304, 116058. https://doi.org/10.1016/j.jep.2022.116058

    Nafici, Saara. 2016. Weed of the Month: Common Blue Violet. Brooklyn Botanic Garden. https://www.bbg.org/article/weed_of_the_month_common_blue_violet

    Plants of the World Online (POWO). 2024. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published at http://www.plantsoftheworldonline.org Accessed on May 10, 2024.

    Rizwan, K., Khan, S. A., Ahmad, I., Rasool, N., Ibrahim, M., Zubair, M., Jaafar, H. Z., & Manea, R. 2019. A Comprehensive Review on Chemical and Pharmacological Potential of Viola betonicifolia: A Plant with Multiple Benefits. Molecules, 24(17). https://doi.org/10.3390/molecules24173138

    Scoppola, A. and Magrini, S. 2019. Comparative palynology and seed morphology in annual pansies (Viola sect. Melanium, Violaceae): implications for species delimitation, Plant Biosystems 153:6, 883-899, https://doi.org/10.1080/11263504.2019.1610113

    Seo, M.N. 2010. Seed coat micromorphology of South American species of Hybanthus (Violaceae). Nordic Journal of Botany 28: 366-370.

    U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2024. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch Accessed May 10, 2024.

    U.S. 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 May 10, 2024.

    World Flora Online (WFO). 2024. http://www.worldfloraonline.org Accessed on May 10, 2024.

    Author(s)

    AUTEUR(S)

    Lyrae Willis, Environmental Science Freelance Writer
    Jennifer Neudorf, Canadian Food Inspection Agency, Canada

    Acknowledgement:
    To Taran Meyer of the Canadian Food Inspection Agency for seed imaging.

    contactus@idseed.org

    Last updated
    on 2023-03-27

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