Taxonomic name: Linaria vulgaris (P. Miller)
Synonyms: Linaria linaria (L.) Karst.
Common names: butter-and-eggs (English-USA, UK), Flachskraut (German-Germany), flaxweed (English-USA, UK), flugblomster (Swedish-Sweden), Gemeines Leinkraut (German-Germany), Gewöhnliches Leinkraut (German-Germany), greater butter-and-eggs (English-USA, UK), gulsporre (Swedish-Sweden), hosoba-unran, inice obecná (Czech-Czech Republic), Jacob's ladder (English-USA, UK), kannusruoho (Finnish-Finland), keltakannusruoho (Finnish-Finland), közönséges gyújtoványfu (Hungarian-Hungary), Leinkraut (German-Germany), linaire commune (French-France), linaire vulgaire (French-France), linajola (Italian-Italy), linnete, lnica pospolita (Polish-Poland), Löwenmaul (German-Germany), nevruzotu, pyštek obycajný (Slovak-Slovakia), ramsted (English-USA, UK), sporrebloma (Swedish-Sweden), torskemund (Danish-Denmark), vlasbekje (Dutch-Netherlands), wild snapdragon (English-USA, UK), yellow toadflax (English-USA, UK)
Organism type: herb
Linaria vulgaris (commonly known as yellow toadflax) is a creeping perennial forb, with bright yellow and orange snap-dragon-like flowers. It is widespread in North America, establishing in rangelands and disturbed areas in western states and provinces. Linaria vulgaris can form dense populations, mainly through vegetative reproduction from root buds along underground rhizomes.
Linaria vulgaris is an herbaceous perennial that can reach a height of about one metre. The stem is glabrous to glandular hairy near the top portion of the stem (CDFA, undated) and develops woody tissue near the base of the stem (Ogden & Renz, 2005). The leaves are 2-5cm long, alternate, sessile not clasping (Ogden & Renz, 2005), linear to narrow, and pale green, soft, often drooping with small hairs (CDFA, undated). The flowers are zygomorphic, resembling snapdragon flowers, forming in racemes of 15-20 flowers(Arnold, 1982) in the axils of the upper portion of the stem and are about 2cm long (Ogden & Renz, 2005). The flower corolla is yellow to pale yellow (CDFA, undated) with an orange bearded throat and yellow spur (Ogden & Renz, 2005) that is about 1-2cm long in which nectar collects (Arnold, 1982). The fruit of the plant is about 1cm long, ovate (ANHP, 2006), two celled capsule that is brown (Ogden & Renz, 2005). The seeds are small, flat, dark brown in colour, with a circular papery wing (CFDA, undated).
Linaria bipartita, Linaria canadensis, Linaria genistifolia, Linaria pinifolia, Linaria purpurea
agricultural areas, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands
Linaria vulgaris is found in farmlands, pastures, rangelands, riparian corridors, along roadsides, railways, clearcuts, and old fields (Holdorf, undated). It can tolerate a wide range of conditions, prefering dry, open habitats (Holdorf, undated) but performing well in dark, wet, and high fertility sites (ANHP, 2006). It is common on chalky soils (USGS, 2006), as well as sandy, gravely soil (ANHP, 2006) and disturbances greatly increase establishment rate although plants can spread from established areas into undisturbed locations (Markin, undated). Yellow toadflax can be found at altitudes of up to 3000 metres in the Rockies (Beck, 2006) and can tolerate sub-artic conditions (CDFA, undated). Its vegetative patterns are typically small open patches or isolated plants widely scattered over large areas (Markin, undated), but large colonies can establish in areas (CDFA, undated). Vegetative reproduction is responsible for the colony forming habit of the plant (USGS, 2006).
Linaria vulgaris can suppress native grasses and compete for soil water resources reducing biodiversity (ANHP, 2006). It also replaces valuable forbs in range and pasture land reducing the efficiency of livestock grazing; livestock do not prefer the taste of yellow toadflax and it is moderately toxic (ANHP, 2006). Yellow toadflax can also be an alternate host for several plant diseases, namely cucumber mosaic virus and broad bean wilt virus (CDFA, undated).
Linaria vulgaris was used primarily as an ornamental due to its beautiful yellow and orange snapdragon-like flowers. It has also been used for medicinal purposes and as a dye (CDFA, undated).
Native range: Europe, British Isles, Russian Federation, China, Turkey (Peat & Fitter, undated; USDA-GRIN, 2007).
Known introduced range: North America, Chile, Guatemala, Jamiaca, Australia, New Zealand, South Africa (ANHP, 2006)
Introduction pathways to new locations
For ornamental purposes: Linaria vulgaris was introduced into North America in the mid-1600s as a perennial ornamental (Holdorf, undated).
Other: L. vulgaris was introduced for use as a folklore remedy (Holdorf, undated).
Local dispersal methods
Garden escape/garden waste: Common toadflax was introduced to North America as an ornamental but subsequently escaped garden cultivation into farmlands and pastures (Holdorf, undated).
Intentional release: Revegetation efforts after road contruction by park personnel and private contractors using alien species seed mixes (Tyser & Worley, 1992).
Off-road vehicles: Heavy equipment can be responsible for the transportation of root fragments which regenerate into new plants (Ogden & Renz, 2005).
On animals: (Markin, undated) states that a common way the seeds are transported is through the attachment onto the fur of animals, humans, and vehicles.
On animals (local): Wind is a potential mechanism for seed dispersal because the seed coat has wings which could facilitate its transport (ANHP, 2006).
Water currents: Water is considered a mechanism of seed dispersal (ANHP, 2006).
Preventitive measures: Prevention may be the easiest, cheapest, and most effective means of control. Stricter regulation of what agents, materials, or development can be brought or done into wilderness areas and public lands needs consideration (ANHP, 2006). An example is the restriction of livestock in nature reserves should be considered (Tyser & Worley, 1992). Monitoring is critical in knowing where invading populations occur and how abundant. It is easier to control small infestations before a population build-up (Curran & Lingenfelter, 2001). Education, awareness programs, advertising and community outreach are all excellent ways to stay informed at a local or regional level and allows earlier detection (Mullin,et al, 2000). Research is neccessary in order to develop new methods and techniques of control and better understand the biology of the species (Mullin,et al, 2000).
Physical: Most physical methods of control for Linaria vulgaris alone are not satisfactory, and not recommended for medium to large stands (Kadrmas & Johnson, undated). Mowing can prevent the plant from going to seed, but mowing also stimulates vegetative reproduction from the lateral roots and rhizomes which can exasberate the problem further (Kadrmas & Johnson, undated). Fire is also not effective because the underground rhizome system is not damaged and will just resprout shoots(Kadrmas & Johnson, undated). Tilling on arable lands can be effective in eradicating L. vulgaris, but tilling needs to be done every 7-10 days over the course of the season and repeated yearly for several years in order to eradicate resprouting root fragments (Ogden & Renz, 2005). Grazing by livestock is also not recommended as it stimulates vegetative growth with viable seeds passing through the digestive tract (Ogden & Renz, 2005). Overgrazing can reduce competition and increase the disturbance to the site creating an ideal environment for toadflax establishment (Kadrmas & Johnson, undated). The plant is not preferred by grazing livestock and contains poisonous glucosides that are moderately toxic to livestock (ANHP, 2006).
Cultural: Some cultural options for control of L. vulgaris is proper timing of seeding agricultural crops, overseeding, fertilizing, using high quality seed, planting at high densities, and using species that are adapted to your region (Curran & Lingenfelter, 2001). Revegetating with native species in particular perennial grasses which are more competitive to perennial forbs is another option (Curran & Lingenfelter, 2001).
Chemical: Chemicals that have shown to be effective in controlling L. vulgaris are glyphosates, a nonselective herbicide, and Telar and Tordon, two selective herbicides, among many others. Repeated applications may be required periodically every few years for up to twelve years. Applications should be timed around flowering when the plants are most vulnerable or after a hard frost (Ogden & Renz, 2005). Integrated management by seeding competitive species shortly after a chemical application has shown to be effective in preventing reemergence (Beck, 2006). Always follow labled instructions for any chemical and make sure that any chemical being applied is not going to kill or reduce the competitive ability of any native species(Kadrmas & Johnson, undated).
Linaria vulgaris has a hemaphroditic (Peat & Fitter, undated), self-incompatible flower that requires cross-pollination in order for viable seed production. The mechanism is through insect pollination (Arnold, 1982). Seed production for an average individual plant is 30,000 seeds (Ogden & Renz, 2005). L. vulgaris has a low viability in seed production with only about a 10% germination rate under field conditions (Ogden & Renz, 2005). The plant can also reproduce vegetatively through the formation of suckers orginating from undergound root buds and buds located on the rhizome. Root fragments as small as 1cm can establish and initiate shoot growth (ANHP, 2006).
Linaria vulgaris sets flower in mid-May to September depending on the location and elevation of the plant (Kadrmas & Johnson, undated). Seed production occurs in the late summer and seed dispersal can continue through the winter (Ogden & Renz, 2005). Seeds germinate best under stratification, cool to cold moist conditions, of 2-8 weeks (CDFA, undated). Seeds can remain viable in soils for up to 8-10 years (ANHP, 2006). Seed germination typically occurs in April or May, but it can be even earlier in warmer regions (Kadrmas & Johnson, undated). The majority of the seed, between 80-90%, falls within a half a metre from the parent plant (Ogden & Renz, 2005). Other seed dispersal mechanisms vary and no clear mechanism is outlined in the literature (Markin, undated); however potential dispersal mechanisms reviewed are wind, water, clinging to the surfaces of animals, vehicles, people, movement of substrates, sold as a contaminant in seed mixes or as an ornamental plant in nurseries (Ogden & Renz, 2005; CDFA, undated; ANHP, 2006).
Principal sources: Ogden, J.A.O. & Renz, M.J., Nov. 6, 2005, Yellow toadflax (Linaria vulgaris), Weed Fact Sheet, New Mexico State University;
Alaska Natural Heritage Program, 2006, Yellow toadflax, Linaria vulgaris P. Miller, Environment and Natural Resources Institute, University of Alaska Anchorage;
Holdorf, R.H., undated, Biological Control of Yellow toadflax (Linaria vulgaris) (L.) (Scrophuliaraceae): Oppurtunities and Constraints Affecting the Reclamation of Rangelands in the Western United States, Restoration and Reclamation Review, University of Minnesota, St. Paul, MN, (USA).
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Friday, 3 August 2007