White campion (Silene latifolia)

Synonyms: Silene alba, Lychnis alba, Melandrium album, Silene pratensis, Silene pratense

Common Names: Evening campion, white cockle, evening lychnis

Description:

White campion (Silene latifolia) is an upright flowering weed in the pink family (Caryophyllaceae), native to Europe, western Asia, and North Africa [1][2][3]. It arrived in North America in the early 1800s, most likely as a contaminant in crop seed, and has naturalized in fields, roadsides, and disturbed ground across nearly the whole country [3]. MISIN tracks it as a non-native weed ? one that is a particular nuisance in hayfields and crops, where its seed mixes into forage and crop seed [3].

Habit:

White campion is an erect, hairy plant, 1 to 3 feet tall, with paired leaves and showy white flowers [1]. The flowers are its best feature: five white petals, each deeply notched at the tip so it looks like ten, about 1 to 1.3 inches across, fragrant, and opening in the evening [1][3]. Behind each flower is an inflated, balloon-like tube (calyx) marked with lengthwise veins, often tinged purple [3].

A useful quirk: white campion has separate male and female plants (it is dioecious), and you can tell them apart by that inflated tube ? the female's is rounder with 20 veins, the male's is slimmer with 10 [1][3]. It blooms from early summer into fall, so the evening-opening white flowers and their inflated calyces are easiest to spot from June through October [1][3].

At-a-glance cues:

1. Five white petals, each deeply notched so they look like ten, fragrant and opening in the evening [1][3]
2. An inflated, balloon-like tube (calyx) behind the flower, with lengthwise veins, often purple-tinged [3]
3. Separate male and female plants ? female calyx rounder with 20 veins, male slimmer with 10 [1][3]
4. Erect, hairy stems that are slightly sticky toward the top, with paired hairy leaves [1][3]

Leaves:

1. Arrangement: opposite (two per node) [1]
2. Shape: lance-shaped to oval, about 1.5 to 4 inches (4 to 10 cm) long [1]
3. Surface: hairy [1]

Stems:

1. Habit: erect, herbaceous, 1 to 3 feet (40 to 120 cm) tall [1]
2. Surface: downy and hairy, and slightly sticky (glandular) toward the top [1][3]

Flowers:

1. Color: white (rarely pink-tinged) [1][3]
2. Form: 5 petals, each deeply notched at the tip, about 1 to 1.3 inches (25 to 35 mm) across, fragrant, opening in the evening [1][3]
3. Calyx: an inflated, veined tube behind the flower ? female flowers rounder with 20 veins, male slimmer with 10 [1][3]
4. Sex: dioecious ? male and female flowers are on separate plants [1]
5. Bloom time: June to October [1][3]

Fruit and seeds:

1. Type: an urn-shaped capsule about 1/2 inch long that opens by 10 upturned teeth [3]
2. Output: a heavy seed producer ? about 500 seeds per capsule and up to about 50 capsules per plant, roughly 25,000 seeds in a season [3]

Habitat:

White campion is native to Europe, western Asia, and North Africa and is not native to North America, where it has naturalized across nearly every state [1][3]. It favors full sun on rich, well-drained soil [3].

Look for it in open, disturbed, and farmed ground ? grain, legume, and vegetable crops, hayfields, field edges, roadsides, shorelines, wood edges, and waste areas [3]. It is a weed of sunny disturbed places rather than shaded natural areas [1][3].

Reproduction:

White campion spreads by seed, and it makes a great deal of it ? up to roughly 25,000 seeds per plant in a season [3]. For a homeowner or farmer, the way it most often arrives is in contaminated seed: its seeds are hard to separate from alfalfa, clover, and grass crop seed, so it rides into new fields mixed with planted seed, and it also spreads when seeding plants are cut and baled into hay [3].

Because it has separate male and female plants, it needs both nearby to set seed [3]. It can behave as an annual, a biennial, or a short-lived perennial depending on conditions [3]. The one control point that matters most follows directly from all that seed: remove plants before the seed capsules ripen, so a plant cannot restock the soil or contaminate a hay crop.

Impact and Damage:

White campion is not toxic and is not a health hazard to people or pets. Its impact is mostly agricultural and economic rather than a threat to natural areas.

Its heavy seed production makes it a costly weed of crops and hay: the seed is difficult to clean out of alfalfa, clover, and grass seed lots, so it contaminates forage and crop seed and gets carried into new fields in baled hay [3]. It is also hard to control, because it produces so much seed and resists several commonly used herbicides [3]. In natural areas its role is smaller ? it is a weed of sunny disturbed ground, field edges, and roadsides that can crowd other plants there, rather than an invader of intact forests or wetlands [1][3]. MISIN tracks it as a non-native weed to report, with the practical goal of stopping seed before it spreads into crops and clean ground [3].

Similar species:

White campion is easily confused with other campions and catchflies. The reliable combination to look for is its white, evening-opening, deeply notched petals together with the inflated, veined tube behind the flower and its separate male and female plants [1][3].

Bladder campion (Silene vulgaris) has an even more inflated, balloon-like calyx that is netted with veins, but its flowers are perfect (each has both male and female parts, so plants are not separate sexes), they open by day, and its foliage is smooth and waxy rather than hairy [1].

Night-flowering catchfly (Silene noctiflora) also has white-to-pinkish flowers that open in the evening and a veined, inflated calyx, but each of its flowers has both male and female parts, and the whole plant is very sticky to the touch [3].

Red campion (Silene dioica) looks almost identical in form and is also dioecious, but its flowers are rose-pink to red rather than white; where the two grow together they cross and produce pink-tinged hybrids [1].

Bouncingbet (Saponaria officinalis) has clusters of pale pink to white five-petaled flowers, but its petals are not deeply notched, its calyx is a plain tube that does not inflate, and it spreads by creeping underground stems, which white campion does not [1].

Monitoring and rapid response:

Signs to watch for:

1. Erect, hairy plants with white, deeply notched, evening-opening flowers and an inflated, veined tube behind each flower, June through October [1][3]
2. Separate male and female plants ? female calyx rounder with 20 veins, male slimmer with 10 [1][3]
3. Plants in sunny disturbed ground ? crop fields, hayfields, field edges, and roadsides [3]

What you can do:

1. Hand-pull or dig plants, taking the root crown, while the soil is moist [3].
2. Remove plants before the seed capsules ripen. Because a single plant can make around 25,000 seeds, and it spreads mainly by seed, stopping seed set is the single most important step [3].
3. Bag and dispose of seeding plants rather than composting them, and do not cut and bale plants that are in seed into hay, which spreads the seed to new fields [3].
4. Clean seed off mowers, balers, and boots before leaving an infested field so you do not carry it to clean ground [3].
5. For a farm or natural area crew: prioritize stopping seed production across the site, use repeated cultivation or mowing timed to prevent seed maturation, and clean equipment between fields ? regular cultivation alone gives only limited control [3].

When to call a professional:

1. Large infestations in crops or hayfields that keep reseeding despite pulling and cultivation
2. Any campion or catchfly you cannot confidently identify ? several look alike, so a photo-backed report is worth more than a guess
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. Native Plant Trust, Go Botany. Silene latifolia (white campion). gobotany.nativeplanttrust.org
2. Global Biodiversity Information Facility. Silene latifolia Poir. gbif.org
3. Ohio State University, OSU Weed Guide. White Campion (Silene latifolia). weedguide.cfaes.osu.edu

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