Securigera varia
(crown vetch)

Pictures

Identity

Preferred Scientific Name

• Securigera varia (L.) Lassen

Preferred Common Name

• crown vetch

Other Scientific Names

• Coronilla haussknechtii Boiss.
• Coronilla hirta Boiss.
• Coronilla varia L.
• Coronilla varia ssp. hirta (Boiss.) Rech.f.
• Securigera varia ssp. Orientalis Jahn

International Common Names

• English: axseed; trailing crownvetch; trailing crown-vetch; vetch (crown)
• Spanish: arvejilla morada; coronilla morada; ruda inglesa
• French: coronille; coronille bigarrée; coronille variée

Local Common Names

• Azerbaijan: ala acryonca
• Belarus: Вязель рознакаляровы
• Czech Republic: Čičorka pestrá
• France: coronille bigarr
• Germany: Bunte Kronenwicke
• Italy: vecciarini
• Lithuania: dvispalvis raženis
• Netherlands: bont kroonkruid
• Poland: cieciorka pstra
• Slovakia: ranostaj pestrý
• Slovenia: pisana šmarna detelj
• Spain: coroneta rosa
• Sweden: rosenkronill
• Ukraine: В'язіль барвистий
• USA: axseed; axwort; crown-vetch; field crownvetch; purple crown-vetch; trailing crown-vetch

EPPO code

• CZRVA (Coronilla varia)

Summary of Invasiveness

S. varia is a perennial herbaceous vine from the pea family that has been introduced into various countries as an ornamental, for erosion control, ground cover, soil improvement, as a cover crop and as fodder/forage for livestock (GISD, 2016, US Forest Service, 2016).

The species is considered a threat in the USA, for its rapid vegetative growth resulting in monocultures and its detrimental effect on the native vegetation (Molano-Flores, 2014; Invasive Plant Atlas of the United States, 2016). The multi-branched rhizomes can extend up to 3 m long; and the stems can extend up to 2 m long; plants can fully cover 20-30 square metres in four years (Molano-Flores, 2014; US Forest Service, 2016). Luneva (2009) cites it as a dangerous weed that is a problem in rye, oat, summer and winter wheat crops and in vineyards; seeds littering the cereal grains, being hard to separate. There are no invasive behaviour reports for the species in western Europe (Alien Plants of Belgium, 2016).

It is reported as invasive in many states of the USA, and in British Columbia in Canada (Molano-Flores, 2014; Casals, 2016; E-Flora of British Columbia, 2016; US Forest Service, 2016). It is included in a list of noxious plants of concern in Mexico, with the recommendation of doing a country assessment for its eradication or containment (Sánchez-Blanco et al., 2012). It is also included in the Global Invasive Species Database of the IUCN (GISD, 2016). An invasiveness assessment carried out for Alaska gave it an invasiveness rank of 68 on a scale of 1-100 (Alaska Natural Heritage Program, 2016).

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Fabales
•                         Family: Fabaceae
•                             Subfamily: Faboideae
•                                 Genus: Coronilla
•                                     Species: Securigera varia

Notes on Taxonomy and Nomenclature

S. varia is a member of the pea family (Fabaceae), in the tribe Loteae, which includes three similar genera: Coronilla, Hippocrepis and Securigera. All have a centre of diversity in the Mediterranean, with a few species in Central and Eastern Europe, SW Asia and the Indian region (Lassen, 1989). Coronilla and Securigera are sister groups with molecular evidence supporting the separation of the two genera (Cano et al., 2012).

Securigera comes from Latin meaning “armed with axe” and varia meaning “variegated, coloured or diverse” (Burnham, 2016). There are at least three S. varia cultivars developed in the USA: 'Penngift', 'Chemung', and 'Emerald', representing ecotypes developed within the past 20 or more years (Gucker, 2009).

Description

The following description is from the Alaska Natural Heritage Program (2016):

S. varia is a perennial legume that grows from extensive rhizomes. Stems are glabrous, spreading, branched above, and 20 to 100 cm tall. Leaves are dark green, alternate, 4 to 16 cm long, and pinnately compound with 7 to 25 leaflets per leaf. Leaflets are oblong to elliptic, 1-3 cm long with papery margins. Stipules are oblong, 2-5 mm long with blunt tips. Flowers are arranged in axillary umbels in groups of 6 to 25. Peduncles are usually longer than leaves. Calyxes are bell-shaped, 2-3 mm long. Corollas are white to purple and 9-12 mm long. Pods are slender, four-angled, ascending, segmented, and up to 6 cm long. Pods contain 3 to 8 seeds each. Seeds are cylindrical, 3-4 mm long, and 1-1.2 mm wide.

Plant Type

Distribution

S. varia is cited as native to Europe, Asia and North Africa (GISD, 2016), although FAO (2016) considers it as native only to Central Europe. While the GISD (2016) and some American sources list it as native to North Africa, no specific country records could be found for this region.

The species is found in Asia, Africa, North America, the Caribbean, South America; Europe and Oceania (See Distribution Table for details). It is recorded in all states of the USA except for North Dakota (US Forest Service, 2016; USDA-NRCS, 2016).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

In Belgium, S. varia is reported near Wilsele since 1894, brought in with cereals, wool and building materials (Alien Plants of Belgium, 2016). It was first reported in Mexico in 1984, as an ornamental coming from Africa (Sánchez-Blanco et al., 2012).

Gucker (2009) summarises the introduction and spread of the species in the USA as follows: “The earliest report of the species in the USA is from 1869 in New York, near the Hudson River. In 1872 it was established and naturalised in openings at woods. In 1890 the species was available commercially in the United States. By the 1950’s it was planted extensively in North America for revegetation of areas and also used as an ornamental, a cover crop or as green fertilizer. By the 1960’s it was abundant in the eastern United States. In 1984 S. varia was regarded as an "especially aggressive" species that excluded native plants. “

Gucker (2009) also reports the spread of the species in some of the states in USA. For example, in Boone County, Iowa, a S. varia patch increased in size from 3,060 m² in 2004 to 3,630 m² in 2005. In 2003, it was found on four sites and 0.2 ha of Michigan's Ottawa National Forest and two years later it was reported on 14 sites and 4.5 ha of the forest. On cut slopes in West Virginia, the species was found 10 m outside of the planting area within 6 years of seeding.

Introductions

Risk of Introduction

S. varia is a perennial vine that is considered as a minor threat in some countries and as highly invasive in others (Gucker, 2009). The risk of introduction is in temperate areas. Due to its aggressive vegetative growth, the species impacts native habitats by reducing the biodiversity, and by causing changes in ecological and successional processes (GISD, 2016). It is also reported as impacting threatened species (Gucker, 2009; Molano-Flores, 2014). The species could be easily introduced to new areas as it is available over the internet and locally to be used for ornamental purposes, erosion control, soil improvement, as a cover crop and as a fodder/forage for livestock (GISD, 2016; Minnesota Wildflowers, 2016; US Forest Service, 2016).

Habitat

In countries where it is reported as introduced, S. varia is found on mesic prairies, weedy meadows, drainage ditches, roadsides, railway embankments, gardens, open fields, waste areas, dry grassy places, utility corridors, forest margins, secondary dunes, banks of rivers and gravel bars along streams (Encyclopedia of Life, 2016; GISD, 2016; PFAF, 2016). In its native range, the species is reported to occur in meadows, grasslands, savannas, and disturbed areas (Gucker, 2009).

Habitat List

Biology and Ecology

Genetics

The reported chromosome number for S. varia is 2n=24 (Löve, 1980).

Reproductive Biology

The primary form of reproduction in S. varia is vegetatively though the production of abundant spreading rhizomes, and regeneration from stem and rhizome fragments (Losure et al., 2009; Gucker, 2009). A single plant can cover 70-100 m² in four years and form dense colonies in some areas (Gucker, 2009).

S. varia is almost dependant on pollinators for seed production (Encyclopedia of Life, 2016). In controlled experiments the number of seeds produced from selfing was extremely low and when insects were excluded from plants in the field, no seeds were produced (Gucker, 2009). The nectar and pollen of the flowers attract long­tongued bees, including honeybees (Gucker, 2009; PFAF, 2016). Megachile addenda and Megachile campanulae have been also been reported as pollinators of the species (Encyclopedia of Life, 2016). Seeds are produced in the second year of growth. Fruits take 6 to 10 weeks to mature after pollination (Gucker, 2009).

Seed remain viable in soil for less than a year to 5 years (Encyclopedia of Life, 2016; GISD, 2016), but are also reported as viable by Gucker (2009) for up to 15 years. Germination period is long, of about 6 months (ZipcodeZoo, 2016). Seed production is low, and is affected by various factors, including high precipitation, low light, low temperatures and availability of pollinators (Gucker, 2009). The germination improves with scarification of the seeds and exposure to warm temperatures of up to 24°C (Encyclopedia of Life, 2016). Losure et al. (2009) report that seeds are important in establishing new populations, but once plants are established the reproduction is primarily vegetative; and in some areas reproduction by seeds is almost non-existent.

Physiology and Phenology

S. varia produces flowers from May through November (GISD, 2016; ZipcodeZoo, 2016). Flowering and seed production occurs throughout the growing season, having open flowers and mature fruits on plants at a time (Gucker. 2016).

Longevity

Gucker (2009) reports the species as "long-lived" up to 20 years; with some plants surviving at the same location for over 50 years.

Associations

S. varia forms associations with root noduling nitrogen-fixing bacteria (PFAF, 2016). It is reported to be compatible with the following non­aggressive grasses: smooth stalked meadow grass (Poa pratensis), cocksfoot (Dactylis glomerata) and timothy (Phleum pratense) (Burnham, 2016).

Environmental Requirements

S. varia will grow on well drained dry to moist, coarse to medium texture soils, including sand, rocky soils, loams, clay and silts. It grows best in soils that are pH 6 and above, but will tolerate a pH in the range of 4.8 to 7.2 (PFAF, 2016).  The species is not tolerant to saline and alkaline soils, but will grow in soils with low fertility (GISD, 2016).

S. varia can withstand droughts and heavy precipitation (up to 165 cm annual), but cannot tolerate flooded soils or anaerobic soil conditions. It will not grow in shade but will tolerate sparse shade in edge of forests (Southeast Exotic Pest Plant Council, 2016). The minimum temperature tolerated is -2°C (US Forest Service, 2016).

Climate

Latitude/Altitude Ranges

Air Temperature

Rainfall

Soil Tolerances

Soil drainage

• free

Soil reaction

• acid
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile

Natural enemies

Notes on Natural Enemies

Seeds of S. varia are reported to be predated in Europe by Bruchidius pusillus beetles (Delobel and Delobel, 2006). Other insects that feed on the foliage of the species are: the Bean Leaf Beetle (Cerotoma trifurcata), a flea beetle (Disonycha punctigera), a leaf­miner fly (Liriomyza trifoliearum), the butterflies Orange Sulfur (Colias eurytheme) and Melissa Blue (Lycaeides melissa melissa), the Wild Indigo Duskywing (Erynnis baptisiae), the Alfalfa Plant Bug (Adelphocoris limbolarius), the Marmorated Brown Stink Bug (Holcostethus limbolarius), the Differential Grasshopper (Melanoplus differentialis), and the Red­legged Grasshopper (Melanoplus femurrubrum) (Illinois Wildflowers, 2016).

Means of Movement and Dispersal

Vector Transmission (Biotic)

Seeds have been found in deer excrement, which are regarded as long distance dispersers (Encyclopedia of Life, 2016).

Accidental Introduction

The species is reported as being accidentally introduced in Belgium through seeds mixed with cereals, wool and building materials (Alien Plants of Belgium, 2016).

Intentional Introduction

S. varia was introduced in the USA and Canada for erosion control, roadside planting and soil rehabilitation (Gucker, 2009). It has been introduced in various countries as an ornamental (PFAF, 2016).

Pathway Causes

Pathway Vectors

Impact Summary

Environmental Impact

Impact on Habitats

S. varia can invade and dominate a variety of habitats due to its prolific vegetative growth, creating dense, single species stands (GISD, 2016). Due to the species’ nitrogen fixing capability, ecosystem functions and nutrient cycling are altered, which causes further degradation of those habitats (Symstad, 2004; Gucker, 2009; GISD, 2016). Fire is reported as having limited spread in dense patches of S. varia and the species being an early successional species after a fire event, which promotes the spread and persistence of the species (Gucker, 2009; Boos et al., 2016).

Impact on Biodiversity

The dense stands formed by S. varia limit the establishment of native species by smothering and/or shading other species, thus decreasing the biodiversity and altering successional processes (US Forest Service, 2016). Gucker (2009) reports that the species limits prairie restoration by reducing seed recruitment, delaying succession, and reducing insect diversity as the main effects of its invasiveness in USA. There are studies of the effect of S. varia on specific species, including its effects on populations of native endangered species (Helianthus eggertii, Leavenworthia exigua and Solidago shortii) and the reduction in the reproductive success of Tradescantia ohiensis (Walck et al., 1999; Gucker, 2009; Molano-Flores, 2014).

The species is toxic to non­ruminant animals because of the presence of nitroglycosides; the consumption in large amounts can cause slow growth, paralysis and death (GISD, 2016; (ZipcodeZoo, 2016). Zuyu et al. (1987) found that chickens that fed on the species had lower plasma glucose, harder and swollen livers with blood spots, lower weight gain and pathological changes in other organs.

Threatened Species

Social Impact

C. varia can be poisonous to single stomached animals, including humans, if ingested in large quantities (GISD, 2016). It is regarded as one of the most toxic plants growing in the United Kingdom (PFAF, 2016).

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Long lived
• Fast growing
• Gregarious
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Negatively impacts agriculture
• Negatively impacts human health
• Negatively impacts animal health
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Poisoning

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

Uses

S. varia can be used as an insecticide, a ground cover, and for erosion control and soil rehabilitation (PFAF, 2016; ZipcodeZoo, 2016). It is used as an ornamental because it grows well on banks, and needs no fertilizing, mowing or weeding (PFAF, 2016; ZipcodeZoo, 2016).

Ruminant animals such as cattle, goats, and sheep, deer and elk forage the species (Gucker, 2009; GISD, 2016). It is recommended as a fodder and forage for livestock; beef cattle will consume the plants if acclimatised first to them (Bryant et al.,1977). It is foraged by deer and elk during the winter (Gucker, 2009). Rabbits, ground nesting birds, and meadow voles use it as cover (GISD, 2016; PFAF, 2016). Caterpillars and butterflies may use it as a host plant (GISD, 2016; Illinois Wildflowers, 2016).

S. varia is used as a cardiotonic, to induce vomiting and to treat rheumatic joints and cramps; caution is recommended due to the toxicity of the plant and the seeds (Encyclopedia of Life, 2016; PFAF, 2016). Oils are extracted from the plant, but no details are given on their use (PFAF, 2016). Sientzoff et al. (2015) report the species as having antitumour and antibacterial activities, as well as flavonoids that had been identified as antioxidant compounds.

Uses List

Animal feed, fodder, forage

• Fodder/animal feed
• Forage

Environmental

• Erosion control or dune stabilization
• Revegetation
• Soil improvement
• Wildlife habitat

Materials

• Oils
• Pesticide

Medicinal, pharmaceutical

• Cosmetic
• Traditional/folklore

Ornamental

• garden plant
• Potted plant

Similarities to Other Species/Conditions

S. varia can be confused with Vicia spp., Lathyrus spp., Chamaecrista fasciculata and Lotus corniculatus. The differences, as discussed by Burnham (2016), are:

Vicia spp. leaves have semi-sagittate to lanceolate stipules, terminating in a tendril; S. varia leaves have oblong stipules and bear a terminal leaflet and tendrils are absent. Vicia inflorescence is a raceme of 1-many flowers, and legumes are not segmented; S. varia inflorescence is an umbel of usually more than 10 flowers, and legumes are segmented.

Lathyrus species differ in having a terminal tendril instead of a terminal leaflet, a raceme inflorescence, and non-segmented legumes.

Chamaecrista fasciculata leaves have an even number of leaflets, yellow caesalpinioid flowers, the stamens are free, and the legumes are not segmented; S. varia leaves have an odd number of leaflets (terminal leaflet present), and the papilionaceous flowers are whitish-pink to purple with diadelphous stamens.

Lotus corniculatus leaves have only 5 leaflets, 2 resembling stipules. The flowers of L. corniculatus are yellow, legumes are dehiscent and non-segmented; S. varia leaves have at least 7 leaflets, and the legumes are indehiscent.

Prevention and Control

Prevention

Published reports, videos and factsheets for the general public are available in the USA through Federal and State agencies (US Forest Service, 2016). It is on regulated and/or invasive species lists in the USA in various states, such as Illinois, Kentucky, Tennessee, Georgia, South Carolina and New Hampshire (Invasive.org, 2016).

Control

Physical/mechanical control

Pulling out the entire plant; mowing and prescribed burning are recommended to slow the spread of the species or act against the seedlings (US Forest Service, 2016). All pieces of the roots need to be removed and populations must be monitored for several years, as seed stored in the soil seed bank may germinate for up to 10 years (GISD, 2016). Follow-up treatment with herbicide is required to control any surviving stems or new seedlings (Gucker, 2009; US Forest Service, 2016).

Chemical control

The use of herbicide is the most effective means to control large infestations (Gucker, 2009; US Forest Service, 2016). The species can be controlled using general use herbicides such as glyphosate, triclopyr, or clopyralid. Multiple applications will be required over a period of several years to prevent regeneration through dormant seeds (Gucker, 2009). The species is tolerant to imazethapyr and imazapic (GISD, 2016).

Ecosystem restoration

The best management approach for the species is one that integrates manual, mechanical, chemical controls, and active habitat restoration efforts (GISD, 2016).

Gaps in Knowledge/Research Needs

Gucker (2009) discusses the need for research related to fires occurring on sites where dense patches of the species occur.

References

Alaska Natural Heritage Program, 2016. Alaska Center for Conservation Science. Anchorage, USA: University of Alaska Anchorage. http://aknhp.uaa.alaska.edu

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Boos T, Kearns K, LeClair C, Panke B, Scriver B, Williams B, 2016. A field guide to terrestrial invasive plants in Wisconsin. USA: Wisconsin Department of Natural Resources. http://dnr.wi.gov/invasives/publications/books.htm

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Bryant HT, Hammes Jr RC, Blaser RE, 1977. Evaluation of acceptability by beef cattle of crownvetch grazed at several stages of maturity., Journal of Animal Science, 45(5):939-944

Burnham RY, 2016. Climbers: Censusing Lianas In Mesic Biomes of Eastern Regions. http://climbers.lsa.umich.edu/?p=3244

Cachovanová L, Hájek M, Fajmonová Z, Marrs R, 2012. Species richness, community specialization and soil-vegetation relationships of managed grasslands in a geologically heterogeneous landscape., Folia Geobotanica, 47(4):349-371

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Casals C, 2016. Securigera varia. Gulf of Maine Research Institute. http://vitalsignsme.org/species_scientific/securigera-varia

Dear BS, Moore GA, Hughes SJ, 2003. Adaptation and potential contribution of temperate perennial legumes to the southern Australian wheatbelt: a review, Australian Journal of Experimental Agriculture, 43:1-18

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Sientzoff P, Hubert J, Janin C, Voutquenne-Nazabadioko L, Renault JH, Nuzillard JM, Harakat D, Magid AA, 2015. Fast identification of radical scavengers from Securigera varia by combining 13C-NMR-based dereplication to bioactivity-guided fractionation., Molecules, 20:14970-14984

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Zuyu L, Xueqin F, Zihua Z, Jing W, 1987. The effects of feeding diets containing Astragalus adsurgens Pall and Coronilla varia L. on broiler chickens., Acta Veterinaria et Zootechnica Sinica, 18(3):157-162

Links to Websites

Contributors

21/08/2016 Original text by:

Jeanine Vélez-Gavilán, University of Puerto Rico at Mayagüez

Distribution Maps