Alternate name: Clasping-leaf Venus' Looking-glass
Family: Campanulaceae, Bellflower view all from this family
Description Wheel-shaped, blue-violet flowers set singly in the axils of clasping, heart-shaped leaves.
Habit: native annual herb; erect, grooved stem, usually single and unbranched.
Height: 4-40 in (10-100 cm).
Leaf: alternate, strongly clasping, heart-shaped, edges wavy or slightly toothed, palmate veins; 0.25-1.5 in (6-38 mm) long, 0.25-1 in (6-25 mm) wide; two opposite, heart-shaped leaves at top of stem.
Flower: blue to blue-violet to deep lavender or rose-pink, 5-parted, radially symmetrical, wide-spreading petals, to 0.75 in (18 mm) wide; solitary, or in clusters of 2 or 3, at leaf axils.
Fruit: small, slender, elongated capsule.
Flower April to August.
Habitat Open, dry sites, often with poor or sandy soil: open woods, cliffs, fields, lawns, pastures, disturbed sites; also cultivated as an ornamental.
Range Native to eastern and central North America, now naturalized and found throughout North America and into Mexico; not reported in Nevada, Alaska, or northern and central Canada.
Discussion Also known as common Venus' looking glass, clasping Venus' looking glass, clasping bellwort, roundleaved triodanis. Considered weedy or invasive in some areas. The flowers in the lower leaf axils do not open but nonetheless produce seeds. The genus name, from the Greek treis (three) and odous (tooth), alludes to the three lobes of the calyx in many of the non-opening flowers. This distinctive annual can appear in any open spot, even in cultivated flower gardens. It is sometimes placed in the genus Specularia.