Sweet autumn virgin’s bower, also called autumn clematis or fall clematis, is a nonnative, invasive perennial, mostly nonwoody vine that is woody at least at the base. It is an aggressive, twining, multiply branching vine that climbs rapidly over any support or else spreads over the ground, forming a dense, tangled mass to 10 feet in diameter. It overwhelms other plants beneath it. In late summer, it produces dense clusters of white, sweet-smelling flowers, which mature into fuzzy seed masses.
Leaves are opposite and pinnately compound with 5 or 7 leaflets. The leaflets are entire (not toothed or lobed), and ovate or heart-shaped; the minor veins are not raised. The elongated leaf stems often curl around objects to support the plant’s climbing habit. The upper surface is green, the lower surface smooth and paler. Sometimes there is an irregular whitish blotch running along the midvein of the leaflets.
Flowers are in dense clusters (cymes). There are (usually) 4 petal-like sepals that are 9–15 mm long; these have the inner surface glabrous (smooth and hairless), though the outer surface is hairy. The flowers open into a general saucer shape (unlike several others in the genus, which resemble urns or bells). Flowers are mostly perfect (they possess both stamens and pistils), though a few staminate flowers are sometimes present, too. Stamens numerous, fairly prominent, white or cream-colored. Pistils 5–6, with long styles, also white or cream-colored. Blooms August–September.
Fruits are flattened oval achenes with the persistent style lengthening and becoming featherlike. The many clusters of achenes, with their plumlike styles, gives the plant a fuzzy look in fall.
Similar species: Eight species of Clematis have been recorded as either native or naturalized in Missouri. In addition to sweet autumn virgin’s bower, two others also bear clusters of white, saucer-shaped flowers and thus might be confused with that species:
- Virgin’s bower (Clematis virginiana), also called woodbine, devil’s darning needles, and love vine, among other names, is a native Missouri plant occurring nearly statewide in bottomland forests, rich, moist upland forests, swamps, banks of streams and rivers, and bases of bluffs. It also occurs in fencerows, railroads, roadsides, and other open, disturbed areas. It blooms slightly earlier than C. ternifolia, in July–August. Identify C. virginiana by its toothed, often shallowly lobed (not entire) leaflets, which usually are 3 (not 5 or 7) per leaf; its flowers being mostly (or all) either staminate (male) or pistillate (female) (not perfect); its petal-like sepals being only 6–10 mm long (not 9–15 mm) and with a few scattered hairs on the inner surfaces (not hairless on the inner surface).
- Catesby’s leather flower (or satin curls, C. catesbyana) is very similar to C. virginiana, but instead of having only 3 leaflets, it has 5 to many leaflets. The leaflets are toothed and usually 3-lobed. Blooms June–August. Scattered in the eastern and southern portions of the Ozarks, in openings and margins of moist, upland forests, on banks of streams and rivers, and along roadsides, mostly on dolomite and chert substrates.
Missouri’s other clematises, such as Fremont’s leather flower (Clematis fremontii), have bell- or urn-shaped flowers that may be white, blue, purple, or greenish and are often nodding. They are not likely to be confused with sweet autumn virgin’s bower.
Stem length: to 20 feet. A mass of this plant can be 10 feet in diameter.
Scattered nearly statewide.
Habitat and Conservation
Introduced, especially found in and near urban areas, where it has escaped from cultivation. Occurs on banks of streams, fencerows, roadsides, railroads, and other open, disturbed areas. Often seen as a weed climbing over hedges and other woody plantings.
This species has been increasing in abundance in Missouri. In the early 1960s, it was reported as naturalized (that is, growing on its own, out of cultivation) from only four counties in southwestern and eastern Missouri, but now it occurs statewide.
Please do not cultivate this plant. It has been recognized as invasive. It outcompetes native vegetation and degrades natural habitats, negatively affecting native plants and wildlife.
Status
Invasive nonnative semiwoody vine. Native to east Asia.
Formerly cultivated in America for its large, attractive clusters of sweet-smelling flowers, it quickly gets out of hand, spreading aggressively by seed into places it’s not wanted. It is a vigorous colonizer of disturbed habitats. Where it spreads into natural habitats, it overwhelms native plants, to the detriment of the entire natural community.
Human Connections
People imported sweet autumn virgin’s bower to America as a landscaping ornamental. Unfortunately, it has proven to be an invasive species that spreads aggressively and harms natural habitats. A single plant produces thousands of seeds, each with a tiny featherlike extension that facilitates dispersal by wind, water, and attachment to animal fur. Once a plant is established, it is perennial, and each year, it can produce thousands more seeds.
Control of sweet autumn virgin’s bower usually involves a combination of herbicides, cutting, and digging out the plant’s root mass. Much depends on the extent of infestation, its location relative to desired landscaping plants, and the time and effort you can devote to the project. Trimming back the plant, then treating with an herbicide, is often a good strategy. Prevent further spread by trimming the plant before seeds are produced.
Many people report this species as a trigger for late-summer hay fever.
Clematis is a big genus in the buttercup family, with about 300 species globally. Some of these are popular garden plants, especially for growing on trellises or walls. Most popular are the many hybrid cultivars with large purple, blue, white, or pink flowers that give way to fuzzy seed heads. In Japan, clematises have been cultivated as ornamentals for hundreds of years.
Ecosystem Connections
Apparently, this nonnative clematis is eaten by the same kinds of moth caterpillars that chew the leaves of our native clematises or other introduced ones. These moths include the spotted thyris (Thyris maculata) and mournful thyris (T. sepulchralis) (both are leaf-rollers in the window-winged moth family), and the brown bark carpet moth (Horisme intestinata), a tan or grayish geometrid whose flat, outstretched wings are marked with fine, dark, parallel lines that run perpendicularly to the insect’s body.
Other insects that may feed on this species include certain kinds of aphids and scale insects that suck the sap and weevils that bore into the stems. The peach leaf-roll aphid (Myzus varians), a nonnative pest on peach trees, uses various species of clematis as its host for the other half of its life-cycle. Certain kinds of leaf-mining insects, such as Phytomyza loewii, create squiggly patterns on the leaflets as they tunnel within the leaf’s inner tissues.
An array of pollinators are attracted to the sweet-smelling flowers of this vine, including bees, wasps, flies, and more.
The leaves of sweet autumn virgin’s bower are acrid and toxic, so few mammals eat these plants.
The masses of vegetation no doubt provide some shelter and nesting space for birds and other wildlife.
