Soapwort is a tall, showy wildflower that has chemicals in its sap that lather up like soap. Native to Eurasia, it has been introduced worldwide and is a common roadside wildflower.
Soapwort is a nonwoody perennial with simple or branched stems, often forming large colonies.
The flowers are in tight or open groups (cymes), subtended by leafy bracts. The flowers are typical of the pink or carnation family: the sepals are fused to form a long, slender tube; petals 5, each with 1 rounded notch, white or pink, showy, with a delightful fragrance.
Blooms June–October.
The leaves are opposite, elliptical to lance-shaped, hairless, to 8 inches long.
Similar species: This is the only species of Saponaria (soapwort) that grows wild in Missouri. Genus Saponaria is native to Europe, Asia, and Africa, not to North America.
- The campions and catchflies (genus Silene) are closely related, but their flowers have 3–5 styles, while soapworts have only 2. Comparing photographs usually separates these plants from one another.
Height: about 2 feet.
Scattered to common nearly statewide; less abundant in northern counties.
Habitat and Conservation
Occurs on banks of streams, rivers, and spring branches; also old fields, pastures, fencerows, old homesites, gardens, railroads, roadsides, and open, disturbed areas.
Native of Eurasia, introduced worldwide. A familiar roadside wildflower, often forming large colonies that are difficult to eradicate, partly because of the toughness of the rhizomes. Even a small portion of a rhizome can send up a flowering stalk, and a single rhizome can generate several stalks.
Cultivars with fancy forms and colors are common in gardens and may persist at old homesites.
Status
Nonnative wildflower. Native of Eurasia.
Human Connections
This plant contains a mucilaginous juice that forms lather in water. In the past, the leaves were often used as a source for soap.
“Bouncing Bet” apparently is an antique English term for a vigorously scrubbing laundry woman (“Bet” being a nickname for “Elizabeth”). It and “soapwort” both describe this tall, showy wildflower, which has chemicals in its sap that lather up like soap. "Wort" is a word that means "herb" or "nonwoody plant."
The seeds contain the same saponin chemicals that cause the sap to lather up, and the seeds are poisonous.
Plants with officinalis in the scientific name usually had medicinal uses in the past.
Ecosystem Connections
Although some butterflies and moths visit, soapwort's flowers aren't very attractive to insects.
Mammals tend not to eat the foliage because of the toxic saponins in the sap.
This plant is weedy, even invasive in some areas. Where it outcompetes valuable native plants, soapwort is a problem.
