clasping Venus' looking-glass (Triodanis perfoliata)
clasping Venus' lookingglass
clasping Venus' looking-glass
common Venus' lookingglass
Legousia perfoliata (L.) Britton
Specularia perfoliata (L.) A. DC.
Triodanis perfoliata (L.) Nieuwl. var. perfoliata
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name for clasping Venus
looking-glass is Triodanis perfoliata (L.) Nieuwl.
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: This native annual plant is generally unbranched and is usually
½–1' tall (rarely taller). The central stem is stiff, light green and deeply
grooved, with lines of small, bristle white hairs along the ridges.
Leaves: The alternate leaves are also light green, and strongly clasp the
stem. However, at the top of the stem are a pair of opposite leaves. These
leaves are about 1" long and nearly as wide. They are cordate to widely
egg-shaped or nearly round, with wavy or dentate margins that are slight-
ly ciliate. Along the margins the leaves may assume a purplish color in
bright sunlight. There is a milky sap in both the stem and leaves.
Flowers: From each leaf axil in the upper half of the plant, are 1-3 flowers, although only one of these will be in bloom at the same time. Each flower
is deep violet, purple or lavendere and about ¾" across. It has a short tubu-
lar corolla with 5 spreading lobes. There are darker lines of purple that con-
verge toward the throat of the flower. The throat is whiter than the rest of
the flower, from which emerges a prominent white pistil and several sta-
mens. There is no floral fragrance. This plant also produces self-pollinating
flowers on the lower half of the stem, whose petals never open.
Fruit/Seeds: The ovaries develop into small oval capsules, which split
open into 3 parts to about the middle. This releases the numerous tiny
seeds, which are lens-shaped and reddish brown. They are dispersed read-
ily by the wind, and can be carried a considerable distance.
Roots: The root system consists of a taproot.
REGENERATION PROCESS: Clasping Venus looking-glass propo-
gates itself by reseeding.
HABITAT TYPES: Habitats include mesic to slightly dry sand prairies,
gravel prairies, upland areas of black soil prairies, sandy savannas, lake
borders, abandoned and dry fields, and areas along railroads and road-
sides, especially where it is gravelly or sandy, often barren, open gound,
especially at clearings, trails, roads. Occasionally a garden weed. The
habitats where this plant occurs have sparser and lower vegetation than
many other areas as a result of poor soil or disturbance.
SITE CHARACTERISTICS: Clasping Venus looking-glass prefers full
sunlight, and mesic to slightly dry soil. This plant flourishes best in poor
soil that is either gravelly or sandy. It doesn't tolerate much competition
from taller plants.
SEASONAL DEVELOPMENT: The blooming period occurs during the
early summer and lasts about a month.
GENERAL DISTRIBUTION: Clasping Venus looking-glass occurs
throughout the continental United States (except Nevada). It does not
generally occur in the Canadian maritime provinces, but does occur in
Quebec and Ontario. It does not occur in the prairie provinces or Alberta,
but does reoccur in British Columbia.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: Small bees are the most common visitors
of the flowers. This includes Little Carpenter bees, Plasterer bees, Green
Metallic bees, and other Halictine bees. The plasterer bee (Colletes brevi-
cornis) is an oligolege of clasping Venus' looking glass. Other insect visit-
ors include bumblebees, flies, small butterflies, and skippers. The seeds
are too small to be of any interest to birds. Mammalian herbivores may
consume this plant, although it is of minor importance as a food source.
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