Description: This native perennial plant is a woody vine up to 20' long. Its stems can twine about fences and adjacent vegetation and they branch occasionally. These stems are initially green or dull red, but they eventually turn brown and woody; young stems are sparsely pubescent, round or angular, and become somewhat enlarged at the base of the petioles. The opposite leaves are primarily trifoliate, although some of them are simple. The petioles of these leaves are up to 2" long; they are green or dull red and sparsely pubescent, like the stems. The leaflets and simple leaves are up to 4" long and 2" across; they are ovate, dentate or shallowly cleft along the margins, and nearly hairless. The underside of each leaf may be slightly pubescent, especially along the major veins. Each leaflet has its own petiole (petiolule); the petiole of the terminal leaflet is longer than those of the lateral leaflets.
Occasionally, flat-headed panicles of
white flowers are produced from the axils of the leaves. Each panicle can span
several inches across. A single vine can produce all staminate flowers (male),
all pistillate flowers (female), or all perfect flowers (both male &
female). Regardless of its gender, each flower is about ¾" across and
has 4 petal-like sepals that are white or cream. Each staminate flower has
abundant long stamens in its center that have white filaments and pale yellow
anthers. Each pistillate flower has several green carpels in its center, each
with a short curly style. Each perfect flower has green carpels in its center,
which are surrounded by one or two rows of stamens. The blooming period occurs
from mid- to late summer and lasts about a month. The staminate flowers quickly
wither away, but each of the pistillate and perfect flowers develop a cluster
of pubescent achenes with elongated styles (up to 2" long) that are more or
less hairy. These achenes and their persistent styles are initially green and
silky in appearance, but they eventually turn brown. Each achene contains a
single large seed. This plant spreads by reseeding itself.
Cultivation: The preference is partial sun, moist to
mesic conditions, and a fertile soil that is loamy or silty. Full sun is also
tolerated, although the leaves may turn yellowish green.
Range & Habitat: Virgin's Bower occurs
occasionally throughout Illinois (see
Distribution
Map). It is a little more common in northern and western Illinois than
other areas of the state. Habitats include edges of
woodlands, moist thickets, moist meadows in floodplain areas, banks of rivers
and large drainage ditches, and fence rows. Virgin's Bower can be found in both
disturbed and natural areas. It is sometimes cultivated as an ornamental garden
plant.
Faunal Associations: The
nectar of the staminate flowers attracts Halictid bees (including Sphecodes
clematidis), wasps, and various kinds of flies. No information is available
for pistillate flowers. The caterpillars of two moths, Thysis maculata
(Spotted Thysis) and Thysis sepulchralis (Mournful Thysis), feed on
Virgin's Bower and other Clematis spp. Birds and mammalian herbivores
apparently don't utilize these species as a food source to any significant
degree.
Photographic Location: A
moist thicket near a drainage ditch in Champaign, Illinois. The flowers in the
upper photograph are staminate.
Comments: The flowers of Virgin's Bower are
attractive and often abundantly produced; the staminate flowers are slightly
more showy than the pistillate flowers. The achenes with their silky-hairy
styles are also interesting because of their unusual appearance. The only other
species that resembles Virgin's Bower in Illinois is Clematis terniflora
(Autumn Clematis), which has been introduced from East Asia as an ornamental
plant. Autumn Clematis is also a woody vine that produces masses of white or
cream flowers. The flowers of this latter species, in my experience, are
slightly larger (about 1" across) and more fragrant than those of Virgin's
Bower. These two species can be easily distinguished by their foliage: The
leaflet margins of Virgin's Bower are dentate or shallowly cleft, while the
leaflet margins of Autumn Clematis are smooth.