Crown vetch (Securigera varia)

Synonyms: Coronilla varia

Common Names: Purple crownvetch, crownvetch

Description:

Crown vetch (Securigera varia) is a sprawling, pink-flowered legume native to Europe, southwest Asia, and North Africa [1][3]. It was widely planted across North America for erosion control on roadsides, banks, and mine sites, and has since escaped to become an aggressive invader [1]. MISIN tracks it because it forms dense mats that smother native plants, it is very hard to remove once established, and it is toxic to horses and other non-ruminant animals [1][2].

Habit:

Crown vetch is a low, sprawling perennial with weak, trailing stems that can reach about 6 feet long and pile up into a heavy mat [1]. Its leaves are divided, feather-fashion, into many small oval leaflets ? usually around a dozen or more pairs ? along a central stalk [1][2]. Its flowers are the giveaway: small pea-type blooms in pink-and-white, packed into rounded, crown-like clusters (umbels) about an inch across on long stalks, blooming from early summer into fall [1][2]. After bloom it forms slender, angular, segmented pods that taper to a point [2]. Below ground it spreads by long rhizomes (creeping underground stems) [1].

It is easiest to spot in summer, when the pink-and-white crown-shaped flower clusters cover roadsides, banks, and open ground in dense sheets [1][2]. The rest of the year, look for the sprawling mats of trailing stems with many-leafleted, feathery leaves [1].

At-a-glance cues:

1. Sprawling perennial forming dense mats of weak, trailing stems up to about 6 feet long [1]
2. Feathery leaves divided into many small oval leaflets [1][2]
3. Pink-and-white pea flowers in rounded, crown-like clusters about an inch across, summer into fall [1][2]
4. Slender, angular, segmented seed pods tapering to a point [2]

Leaves:

1. Arrangement: alternate along the stem; each leaf divided feather-fashion (odd-pinnate) into many leaflets [1]
2. Leaflets: about 7?25 small, oblong leaflets per leaf, with smooth edges [1][2]
3. Size: leaves roughly 2?6 inches long [1]
4. Tendrils: none ? unlike the true vetches, the leaves do not end in climbing tendrils [1]

Stems:

1. Habit: a herbaceous (non-woody) perennial; weak, trailing stems up to about 6 feet long, sprawling into a heavy mat [1]
2. Roots: spreads by long, branching rhizomes (creeping underground stems) that can reach 10 feet or more [1]

Flowers:

1. Color: pink and white (sometimes rose) [1][2]
2. Shape: small pea-type flowers, about 6?25 packed into a rounded, crown-like cluster (umbel) about an inch across, on a long stalk [1][2]
3. Arrangement: umbels held above the foliage on long stalks [1]
4. Bloom time: early summer into fall [2]

Fruit and seeds:

1. Fruit type: a slender, angular, segmented pod that tapers to a pointed beak, about ??2 inches long [2]
2. Seeds: several per pod; reported to be poisonous [1][2]
3. Dispersal: by seed (which mostly drops near the parent but can be carried in animal droppings) and, most importantly, by spreading rhizomes and rooting stem fragments [1]

Habitat:

Crown vetch is native to Europe, southwest Asia, and North Africa and was introduced to North America, where it was first recorded in 1869 and later planted heavily ? starting in the mid-1900s ? for erosion control on road cuts, banks, mine sites, and railroad embankments [1][3]. From those plantings it has spread widely into the surrounding landscape [1].

It grows in open, sunny, disturbed places on well-drained soils, and tolerates a range of soil conditions [1]. Look for it along roadsides and rights-of-way, in open fields and grasslands, on gravel bars and stream banks, and on the edges of open woodlands [1].

Reproduction:

Crown vetch spreads two ways, and the underground one drives its takeover. It sets seed in slender pods, and that seed can be carried to new ground ? it has even been found sprouting from deer droppings [1]. But its main mode of spread is by long, branching rhizomes that creep outward underground (reaching 10 feet or more) and send up new shoots, so a single plant fans out into a widening mat ? and a stem fragment with a joint can also root [1].

As a long-lived perennial, it persists and thickens from year to year through those rhizomes [1]. For control, that means cutting the top growth is not enough; the rhizomes must be dealt with, and the best timing for cutting or mowing is in late spring around the flower-bud stage, before the plant builds a dense mat and before seed sets [1].

Impact and Damage:

For homeowners, crown vetch carries a real toxicity caution alongside its weediness. It contains compounds (nitroglycosides) that are reported to be toxic to horses and other non-ruminant animals, and its seeds and foliage are reported poisonous, so it is a plant to keep away from horse pastures; grazing livestock such as cattle, sheep, and goats can tolerate it [1][2]. In a yard or on a bank, its trailing stems form thick mats that smother garden plants and are very difficult to dig out because of the spreading underground stems [1].

For natural area stewards, crown vetch is a serious invader of open habitat. Its dense growth builds monocultures that gradually choke out native grasses, wildflowers, and even woody seedlings, and it has been documented excluding native plants from open woodlands and slowing tree-seedling establishment on revegetated sites [1]. Because it was sown so widely for erosion control and spreads aggressively by rhizome and seed, it is established across much of the country, and catching new patches early is far easier than removing established mats [1].

Similar species:

Crown vetch is most often confused with the true vetches, which are also sprawling legumes with feathery, many-leafleted leaves. Its surest marks are its pink-and-white, rounded, crown-like flower clusters and its leaves that lack climbing tendrils [1].

Cow vetch (Vicia cracca) is a common sprawling legume of the same open, disturbed ground. It is told apart by its violet-blue flowers crowded along one side of a stalk and by the curling tendrils at the tips of its leaves, which crown vetch lacks [1].

Hairy vetch (Vicia villosa) is another climbing vetch, also called winter vetch. It is separated by its blue to blue-and-white flowers, its long spreading hairs, and its leaf-tip tendrils, unlike crown vetch's pink-white crowns and tendril-free leaves [1].

American vetch (Vicia americana) is a native vetch worth keeping rather than removing. It is distinguished by its bluish-purple flowers and its climbing tendrils, versus crown vetch's pink-white umbels and sprawling, tendril-free habit [1].

Monitoring and rapid response:

Signs to watch for:

1. Dense mats of sprawling, trailing stems on roadsides, banks, fields, and open ground [1]
2. Feathery leaves divided into many small leaflets, without climbing tendrils [1]
3. Pink-and-white, crown-like flower clusters about an inch across, summer into fall [1][2]

What you can do:

1. Pull or dig out small, young patches, removing as much of the underground stems (rhizomes) and roots as you can ? pieces left behind resprout [1]
2. Cut or mow larger stands in late spring, around the flower-bud stage, to weaken the plants and prevent seed ? repeat through the season and over several years [1]
3. Bag and dispose of plants that are flowering or in seed rather than composting them [1]
4. Wear gloves and keep the plant and its seeds away from horses and other non-ruminant animals, since they are reported toxic [1][2]
5. Replant cleared ground with native cover so it doesn't simply refill with crown vetch [1]
6. For natural areas, crews can prioritize small outlier patches and the edges of open woodlands first, combining repeated cutting with native revegetation across a site [1]

When to call a professional:

1. Large or well-established mats, especially on steep banks or rights-of-way, where hand removal cannot keep up [1]
2. Sites where it keeps resprouting from rhizomes despite repeated cutting [1]
3. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Gucker CL. Securigera varia. In: Fire Effects Information System (FEIS), U.S. Department of Agriculture, Forest Service. research.fs.usda.gov/feis
2. North Carolina State Extension Gardener Plant Toolbox. Coronilla varia (Crown Vetch). plants.ces.ncsu.edu
3. Plants of the World Online (POWO), Royal Botanic Gardens, Kew. Securigera varia (L.) Lassen. powo.science.kew.org

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