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Species
Tanacetum vulgare L. (1773)
IUCN
NCBI
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More info for the term: density
Common tansy occurs nearly throughout the United States and Canada. It is reported in all US states except Texas, Alabama, Georgia, South Carolina, and Florida, and in all Canadian provinces except Nunavut [94]. Common tansy is native to Eurasia, specifically subalpine river valleys in Siberia [40]. Other common tansy habitats in Eurasia are likely the result of widespread human introduction [21,40].
In nonnative US habitats, common tansy is generally more common in the North than in the South. It is common along the Pacific Northwest Coast from northern Oregon to southern British Columbia [70]. It is uncommon in California [30] and restricted to the northern parts of Nevada [44] and New Mexico [58]. Although widely distributed throughout the Great Plains, common tansy is still considered infrequent [26]. Common tansy is frequent in the Northeast. It occurs in nearly every county in New England and New York [57] but is infrequent in North Carolina [77] and West Virginia [87]. In many US and Canadian habitats, common tansy is considered widespread or well established, although populations are often infrequent or scattered. Plants Database provides a distribution map of common tansy.
Common tansy seed was brought to the United States as early as 1631 [54], and because of its many medicinal uses (see Other Uses), common tansy was widely cultivated in the gardens of early European settlers [52,62,87]. Common tansy was one of many seeds brought to the New England Plymouth colony by John Winthrop Jr in 1631 [54]. In the 1600s, the governor of Massachusetts referred to common tansy as a necessity in colonial gardens and encouraged extensive cultivation [52]. John Josselyn wrote in 1638 and again in 1663 that common tansy was "flourishing" in New England herb gardens [62]. By 1785, common tansy was considered "naturalized" in the Northeast. In 1895, Darlington wrote that common tansy had escaped cultivation and was becoming "something of a weed-- in many places". In 1892, common tansy was known on Block Island, Rhode Island [5], and in West Virginia [12]. Common tansy occurred in Michigan by at least the 1860s and was widespread by the 1890s [97]. By 1912, common tansy was reported in Iowa and Kansas [40,63]. Likely common tansy was also introduced on the West Coast of North America. Common tansy occurred in Alberta by the late 1800s [101] and in Oregon between 1891 and 1900 [23]. There were reports of common tansy in Wyoming by 1910, in Idaho and Washington by 1921 [23], and in Montana by 1931 [40]. Common tansy was considered widespread in California by 1952 [52] and well established in Utah by the late 1950s [37].
While no studies measured the spread rate of common tansy, several references provide anecdotal information about its spread. Land owners and managers in Alberta's forested areas reported that common tansy spread has been minimal even though populations have been present for more than 60 years. Land owners and managers in agricultural areas, however, reported increases in common tansy population density and size over time [101]. When western weed scientists were asked to estimate the spread rate of common tansy in the northwestern United States, estimates averaged 11% [95]. It was unclear if these estimates were for increases in population size or density or both. Researchers in Wyoming reported in the 1980s that common tansy was no longer restricted to ditch banks, fence rows, and roadsides and was establishing in rangelands and pastures [20]. Although deliberate human spread of common tansy was more common in early settlement times, more recent inroductions have also occurred. In the mid-1970s, common tansy was planted on reclaimed mine sites in Wyoming [38], and in the mid-1990s, common tansy seed was available in US plant nurseries [55].
More info for the terms: cover, litter
Common tansy seedling establishment and growth are generally best on open sites with limited litter, little established vegetation, and high light levels.
During seeding trials in Thorhild County, Alberta, researchers reported that common tansy establishment and growth were best on sites with low amounts of ground cover and little to no litter. Common tansy failed to establish on sites with high cover of established vegetation and litter [101]. In the Netherlands, common tansy often establishes after large soil disturbances and is common in pioneer communities and at field edges. During a field study conducted in Wageningen, Netherlands, common tansy seedling growth and survival were better on bare ground than on 1-year-old and 2-year-old fields. Light levels were highest and total vegetation biomass was lowest on bare sites. Researchers planted 750 common tansy seeds, and establishment was poor, although 81% of seeds germinated [46].
| Environmental characteristics and outcomes of common tansy seeded on 1×1-m field plots [46] | |||
| Plot characteristics, ~1 year after seeding | Bare ground | 1-year-old field | 2-year-old field |
| Average vegetation biomass (g/m²) | 473a | 628b | 588ab |
| Ambient light at ground level (%) | 7.3a | 1.4b | 1.7b |
| Common tansy seedling characteristics, 1 year after seeding | |||
| Number of common tansy seedlings/m² | 21 | <5 | <5 |
| Seedling mortality (%) | ~50 | ~100 | ~20 |
| Average seedling dry weight (mg) | ~150 | ~0 | <15 |
| Final seedling biomass (g) | 1.650 | 0 | 0.02 |
| Plot characterisitics within a row followed by different letters are significantly different (P<0.05) | |||
More info for the terms: cover, fire management, forbs, formation, fresh, invasive species, litter, natural, prescribed fire, rhizome, shrubs
Impacts: Most predictions and descriptions of common tansy's impacts on water resources, vegetation, and wildlife are anecdotal (e.g. [1,40,52,85,89]). Although many suggest that impacts are likely because of common tansy's sometimes aggressive establishment and growth, detailed study and documentation are lacking. However, in one study [18], researchers found that common tansy ecotypes from Canada grew larger and produced more flowers than ecotypes from Norway, suggesting that common tansy may have greater growth and reproductive potential in its nonnative habitats. In another study [13], common tansy dominated other forbs after seeding and successfully invaded plots with established grasses.
General: Reviews and other technical publications often report that dense common tansy populations may negatively impact water flow, native vegetation, and wildlife habitat, although documentation of these impacts is typically lacking. A review reports that dense common tansy patches can restrict water flow along irrigation ditches and streams in Alaska [1]. In a gardening guide, Sperka [85] reports that in Wisconsin she has "seen acres taken over" by common tansy. According to fact sheets and other technical reports, thick common tansy clumps and dense populations may crowd out other forbs, grasses, and shrubs, potentially reducing the forage value of pasture or rangelands, decreasing wildlife habitat, and reducing species diversity [40,52,89]. Western weed scientists estimated that common tansy infestations lead to an average 50% reduction in carrying capacity on public lands [95]. It was not clear whether this estimation was specific to cattle, all livestock, or livestock and wildlife. It is important to note that some report heavy grazing of common tansy by domestic sheep; however, supplemental feed may be necessary. For more information, see Biological control.
Several sources have predicted common tansy's potential to invade certain areas and habitat based on general information on reproduction, establishment, growth, and dispersal potential. Based on common tansy's climatic tolerances, biological traits, and invasiveness in other natural areas, researchers expected Canada's Riding Mountain National Park was at high risk for establishment and proliferation of common tansy, especially if there were persistent disturbances in the park [68]. Based on occurrence and distribution data and an analysis of factors influencing plant invasions, researchers predicted that given a disturbance, common tansy could grow in any forest type in the Cascade, Sierran Steppe, and Northern, Southern, and Middle Rocky Mountain ecoregions in the northwestern. In riparian areas in the same region, disturbances may not be required for common tansy establishment and growth [69].
Studies: Plant size and reproductive capacity were greater for common tansy ecotypes in Canada than for ecotypes in Norway. Common tansy seed collected from 3 Norwegian ecotypes and 2 Canadian ecotypes was grown in a greenhouse, and when seedlings were about 4 inches (10 cm) tall, they were planted in June in an experimental field in Hedmark, Norway. By September, Canadian ecotypes were significantly taller and produced significantly more biomass (P<0.05) than Norwegian ecotypes. Proportion of dry matter that was stems, leaves, and flowers was not significantly different between ecotypes, but the dry weight of stems and flowers was generally greater for Canadian than Norwegian ecotypes [18].
During a field experiment conducted in Silwood Park in Ascot, England, within 7 years common tansy dominated 11 of 18 plots where it was seeded with up to 79 other herbaceous species. Common tansy also successfully invaded nearby plots seeded with up to 4 perennial grass species. Researchers suggested that a variety of common tansy growth characteristics made it competitive [13]:
- leaves often remained green through the winter
- shoot growth was rapid by early spring
- common tansy canopies produced dense shade
- "bulky" roots and rhizomes monopolized underground space soon after establishment
Allelopathy: Based on controlled studies conducted on seed collected from fields near Keszthely, Hungary, common tansy may affect germination of associated plant species but may not affect plant growth. Common tansy extracts did not affect germination of winter wheat but reduced soybean, corn, and sunflower germination by 20%, 30%, and 96%, respectively. Common tansy extracts rarely reduced the fresh or dry weight of crop plants and often stimulated crop growth [6].
Control: Preventing establishment and spread of common tansy is likely the most cost-effective control method [11,52]. If control methods are necessary, the potential for the establishment of other invasive species must be considered and their success mitigated [8]. Monitoring in control areas is necessary to eliminate common tansy sprouts or seedlings [41]. A photo of common tansy seedlings and descriptions of seedling characteristics are provided by Royer and Dickinson [83]. As with most biotic invasions, common tansy control is likely most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [56].
Prevention: Several practices may limit common tansy establishment and spread. These include: maintenance of desired vegetation [11,56,84], limiting grazing to less than 60% defoliation in areas with common tansy, holding livestock for 2 weeks after grazing in infested areas, minimizing disturbances in areas with and without common tansy, and washing mowing or tilling equipment [52,89]. Although common tansy is rarely a problem in crop fields, it is often common along field margins, and rhizome pieces may be spread within and between fields. It is recommended that equipment be cleaned after use in fields with common tansy [40]. Managing to maintain the integrity of native plant communities and limiting those factors that increase an ecosystem's invasibility are likely to be more effective than managing solely to control the invader [33].
Another important measure in preventing common tansy establishment and spread should include making seed and plants unavailable for purchase. As of 1990, common tansy seed was available for purchase from US plant nurseries [55].
Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [93]. See the Guide to noxious weed prevention practices [93] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.
Fire: For information on the use of prescribed fire to control this species, see Fire Management Considerations and Integrated management.
Physical or mechanical control: Hand-pulling small common tansy populations and mowing larger populations prior to flower and seed development are potentially useful control methods; however, both may be more effective when paired with seeding of desired species, maintenance of associated established vegetation, and/or other control methods [11,40,52]. Because common tansy regenerates from rhizome fragments, cultivation may increase population size [102].
Persistent hand-pulling may be effective in controlling small populations if most or all rhizomes are removed. Seeding areas disturbed by hand-pulling with desired species may decrease the potential for reestablishment [40]. Common tansy can cause dermatitis [30], so precautions should be taken when hand-pulling.
Several sources indicate that common tansy populations may be controlled through mowing. Lackschewitz [49] reported that in Montana common tansy became "less common" with the implementation of right-of-way mowing. Mowing operations should be timed to prevent common tansy flowering or seed set, and mowing heights should be set at a height that limits damage to native and other desirable species [40,52]. Mowing common tansy populations after seed set may increase seed and population spread [40]. In northern Switzerland, common tansy cover was 70% in mowed wildflower strips and 59% in strips left fallow. Mowing occurred in late winter [47] and likely increased the dispersal distance of the previous season's fallen and still attached seed.
Reproductive potential of common tansy was decreased by single high-intensity defoliation and muliple low-intensity defoliation events in roadside and riparian habitats near George Lake, Alberta. Flower head production was significantly lower for plants with 100% of leaves removed than for control plants (P<0.05). Effects of 50% leaf removal, however, were not significant. Defoliation when flower buds were fully formed did not disrupt flower formation. The researcher suggested that mowing may be most effective before flower bud development but may need to be repeated when 50% or more of flowers have bloomed to prevent late flower head development [101].
Biological control: There have been no insect, disease, or fungal biocontrols released for common tansy [101], but potential biocontrol insects have been identified and are being studied [40]. Domestic sheep and goats, however, may be useful biolgical control agents [19]. Cattle typically avoid common tansy; by grazing associated grasses and other vegetation, they may increase the area available for common tansy establishment and/or spread via rhizome growth [52].
Domestic sheep grazing in dense common tansy patches can release grasses by allowing light through the canopies. In Montana, a researcher used sheep to graze common tansy and suggested that "if we can increase the number of sheep in that community then we will never have to worry about tansy again" [19]. Common tansy biomass and spread were reduced by sheep grazing on 2 ranches in Lemhi County, Idaho. In enclosures with dense common tansy populations, repeated sheep grazing was monitored. Enclosures were grazed first in the spring and again when immature flower heads were forming. Common tansy biomass decreased after the first few grazing visits, and the researchers noted that spread of common tansy into adjacent pastures also decreased. When plants were maintained in a vegetative state by sheep, cattle also fed on common tansy plants. During this study, sheep were supplied lots of water to flush the highly fibrous common tansy plant material through their digestive systems. Since common tansy provides only 4% crude protein, the researcher noted that dietary supplements may also be necessary [59].
In a sheep-grazed pasture in Alberta, the shoot number for established common tansy plants steadily and significantly decreased. These decreases did not occur on the cattle-grazed pasture. In the sheep pasture, however, common tansy seedling densities were high. The researcher suggested that decreased litter and increased bare ground on sheep-grazed pasture facilitated the establishment of common tansy seedlings [101].
Chemical control: While several sources provide information on herbicides that may be useful in controlling common tansy [20,52], herbicide use may be restricted along ditch banks or in other riparian habitats and may not be the best option in areas where associated desirable species may be harmed [19].
If herbicide use is considered the best option or is used in conjunction with other control methods, applications should be timed to maximize herbicide effectiveness. Studies in Alberta tracked patterns in the allocation of carbohydrates to roots and rhizomes and suggested that in ungrazed habitats, herbicide applications before flower heads bloom should be most effective [101].
Herbicides may be effective in gaining initial control of a new invasion or a severe infestation, but rarely do they provide complete or long-term weed management [10]. See the Weed Control Methods Handbook [90] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals.
Integrated management: Utilizing multiple control strategies may provide the most successful and long-term control of common tansy. Jacobs [40] suggests that integrated management options should be determined by invasion stage. For small populations or at the early stage of invasion, he suggests herbicide applications, then cultural practices to encourage growth of native plants. For large-scale infestations or large populations, prioritized treatments are recommended. The first priority should be treatment and control of satellite populations to decrease spread rates. Next, parent populations should be treated with a combination of fire, mowing, grazing and/or herbicides. Populations should be monitored to evaluate treatment effectiveness, locate regenerating populations, and plan future treatments [40]. The use of fire with other control methods is discussed more in Fire Management Considerations.
VIII, IX, X, XII
| License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
| Rights holder/Author | Pablo Gutierrez, IABIN |
| Source | No source database. |
More info for the term: marsh
Common tansy seeds generally germinate best when near the soil surface, cold stratified, and then exposed to warm temperatures. Prach and Wade [71] reported that common tansy seed germinates under a wide range of environmental conditions and lacks complicated dormancy mechanisms. A weed guide reports that germination of common tansy seeds is best from the top 0.8 inch (2 cm) of soil [83]. About 75% of seeds collected in October from Gallatin County, Montana, germinated in the laboratory after 1 month of cold stratification [40].
Cold temperatures increased the germination rate of common tansy seed collected from populations in Alberta. Just 10% to 20% of seeds collected in late-July through mid-August germinated without cold treatments. Seeds produced in August or September and collected in October germinated at a rate of 10% without cold stratification and 40% with cold stratification. Seeds collected from overwintering stems germinated at a rate of 70%, and this rate increased to 90% with additional cold treatments. Dispersal of some viable seed in August, and even more after winter, suggests that common tansy seedlings emerge in both the fall and spring, although numbers are likely much greater in the spring [101].
Warmer temperatures led to significantly (P<0.05) greater emergence of common tansy from soil samples collected in June from willow (Salix spp.) savannas in the Peace-Athabasca Delta of northeastern Alberta. Just 2 common tansy seedlings emerged from 85 cm² × 10 cm soil samples at alternating temperatures of 68 and 50 °F (20/10 ° C), but 19 seedlings emerged at temperatures of 86 and 59 °F (30/15 °C). Common tansy emergence from wetter habitat types that included a wheat sedge (Carex atherodes) marsh and a bluejoint reedgrass (Calamagrostis canadensis) meadow was very low regardless of temperature. Researchers suggested that increases in temperature, evapotranspiration, and disturbance expected with climate change in the area may favor common tansy reproduction and persistence [35,36].
The preference is full or partial sun and moist to slightly dry conditions. Common Tansy does well in ordinary garden soil containing loam or clay-loam. It is little bothered by pests and disease, although some of the lower leaves may shrivel up and turn brown during a summer drought. After the blooming period, the substantial foliage begins to turn brown in patches and becomes ragged-looking in appearance.
| License | http://creativecommons.org/licenses/by-nc/3.0/ |
| Rights holder/Author | Copyright © 2002-2014 by Dr. John Hilty |
| Source | http://www.illinoiswildflowers.info/weeds/plants/cm_tansy_cr.htm |
Chile Central
| License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
| Rights holder/Author | Pablo Gutierrez, IABIN |
| Source | No source database. |
More info for the terms: pappus, rhizome
Many passive and active dispersal methods are reported for light-weight (<0.05 g) common tansy seed [101]. Because common tansy seeds lack a pappus [71], long-distance wind dispersal is unlikely unless seeds fall on crusty snow. Winter seed dispersal is likely since seeds are typically attached to flower heads through the fall, but movement of the stiff, dry stems can dislodge common tansy seeds from the flower head and contribute to dispersal anytime seeds are mature [40]. White [101] reports that common tansy seed may remain in flower heads on dead stems for up to 3 years.
Several researchers report that common tansy seed is also transported by water [19,101,102]. Common tansy seeds have high oil content and floating has been observed, although floating duration was not reported [101]. In Wisconsin, common tansy is especially common along ditch banks, and water-dispersed seed is considered important to the colonization of waterways [102].
Animals and humans are also likely dispersers of common tansy seed. According to Sperka [85], birds feed on common tansy seeds; however, viability of seed passing through the digestive tract was not tested. Common tansy seed in animal fur, bird feathers, and soil caught in paws, hooves, or shoes may also contribute to dispersal. Seed dispersal by equipment used in areas with common tansy is also likely [40]. White [101] reports that common tansy is often found in gravel pits and roadside habitats, where equipment use is generally heavy. If common tansy flower heads are present in hay fields, they could also be transported in hay bales [40]. Dispersal of rhizome fragments also contributes to the spread of common tansy (see Vegetative regeneration).
More info for the term: cover
Several sources report that animals feed on common tansy. Sperka [85] reports that birds feed on common tansy seeds. Horses and cattle may feed on young common tansy but avoid maturing and mature plants. Domestic sheep and goats feed on common tansy with "great enthusiasm" [19]. In Montana, most classes of livestock and some wildlife species, including elk, have been observed feeding on common tansy [40]. Grazing of common tansy by domestic sheep is discussed more in Biological control.
Palatability and/or nutritional value: Although some report that common tansy is "mildly" to very poisonous to animals [88,103], no direct link between consumption of common tansy and cattle death or abortions has been established in the United States or Canada (personal communications cited in [101]). In Montana, livestock and wildlife species observed feeding on common tansy displayed no adverse effects [40]. It is reported that dairy cows feeding on common tansy may produce "unpleasant" tasting milk [31].
Cover value: No information is available on this topic.
More info for the terms: ecotype, pappus, perfect, rhizome
Botanical description: This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Because common tansy can be confused with threatened native tansy species, correct identification is necessary prior to control treatments (see Common tansy look-alikes). Keys for identification are available (e.g., [24,26,32,57,77]).
Aboveground description: Common tansy is a robust perennial with erect stems that may reach 7 feet (2 m) tall [32,39,65,100]. Coarse stems generally branch only at the top and are somewhat woody at the base. Stems may grow singly or in clusters [11,26,30,83,88] and are lined with alternate leaves [65,77]. When crushed, leaves produce a "rank" smell [99]. Leaves are finely dissected and toothed. They measure 2 to 12 inches (6-30 cm) long and are generally half as wide [2,26,44,58,81,83]. Climate and/or site conditions may affect plant growth, development, and life span. When 20 common tansy ecotypes collected throughout Finland were grown in a common garden in Helsinki, average ecotype height ranged from 23.8 to 45.5 inches (60.5-115.4 cm) [45]. In Minnesota, common tansy generally grew to 3 feet (1 m) tall but could reach 5 feet (1.5 m) tall in shaded areas [61]. In Alberta, common tansy plants along roadsides and riparian areas were 41 to 63 inches (105-160 cm) tall. There were no significant height differences between the 2 habitats, but during the 3-year study, plant height decreased in the riparian area and increased along the roadside. Stem diameters were significantly less in the riparian area than on the roadside (P<0.01) [101]. In early-seral habitats in South Bohemia in the Czech Republic, common tansy "showed signs of senescence" at 3 to 4 years old [66]. In Gallatin County, Montana, common tansy plants on moist stream banks averaged 3 to 4 years old, and 10-year-old plants occurred on drier sites. Plant age was estimated from rhizome growth rings [40].
| Common tansy flower heads are comprised of daisy-like disk florets and measure up to 0.5 inch (1.2 cm) wide [39,61]. Within the flower head there may be as many as 100 individual florets [40]. Florets are perfect except for the outermost, which are pistillate [17,26]. Generally florets are without ray flowers, but in some cases, reduced ray flowers are present [28,57,81,83]. Flower heads are densely clustered in flat-topped terminal inflorescences [11,49]. Sources report that common tansy may produce more than 8 flower heads/stem [57] and between 20 and 200 flower heads/plant [1,26]. When common tansy ecotypes from Finland were grown in a common garden, the average number of flower heads/stem ranged from 17.6 to 79.8 [45]. Common tansy produces achenes that measure 1 to 1.8 mm long; the pappus, if present, is a reduced 5-toothed crown [1,14,17,30,40,77]. In Alberta, common tansy seeds collected from plants along a roadside weighed significantly less than seeds collected from plants in a riparian area (P=0.046) [101]. |
| Photo © Steve Dewey, Utah State University, Bugwood.org |
Belowground description: Anecdotal descriptions of common tansy roots and rhizomes are more common than measurements. Common tansy rhizomes have been described as "leafy", "robust" [32], "sturdy" [49], and "stout" [26,30]. Rhizome growth has been described as "vigorous" [49]. Rhizomes branch extensively and produce many fibrous roots [85]. Common tansy plants along roadsides and in riparian areas in Alberta produced "tightly coiled" rhizomes with diameters of 0.4 to 1 inch (1.0-2.7 cm) and "extremely woody" roots with diameters that averaged 0.4 cm. Roots extended more than 51 inches (130 cm) below ground [101]. In Gallatin County, Montana, common tansy rhizomes measured 0.5 to 0.75 inch (1-2 cm) thick. Roots were extensive but shallow, and most occurred in the top 23 inches (60 cm) of soil [40].
Common tansy look-alikes: In several parts of common tansy's nonnative North American range, there are similar-looking plants that are threatened, endangered, or occur in threatened habitats (as of 2009). Lake Huron tansy (Tanacetum bipinnatum subsp. huronense), a native North American species, is endangered in Wisconsin, threatened in Michigan, and a species of concern in Maine. Lake Huron tansy is shorter (16 to 32 inches (41-81 cm)) and generally produces fewer and smaller flowers than common tansy [94,102]. Lake Huron tansy also occurs in Canada and Alaska and is often distinguished from common tansy by its lack of a creosote-like odor [1,94]. Camphor tansy (T. camphoratum) is native to Washington, Oregon, and California, and although not listed as a threatened or endangered, grows in habitats described as threatened. Camphor tansy is typically distinguished from common tansy by the more rounded teeth on its leaves and shorter stature (only about 2 feet (0.6 m) tall) [40].