Triodanis perfoliata (L.) Nieuwl.

Clasping Venus' Looking Glass

Triodanis perfoliata plant

Family - Campanulaceae

Stems - To .75m tall(typically less), simple, 5-angled, herbaceous, erect, with milky sap. Angles slightly winged(the wings to .5mm broad), typically hispid.

Triodanis perfoliata stem

Leaves - Alternate, clasping and surrounding the stem(perfoliate), coarsely serrate to crenate, to 2cm long, reduced above, broadly ovate, glabrous above, typically scabrous(strigose) below. Margins stigillose.

Triodanis perfoliata leaf

Inflorescence - One, two, or three sessile flowers from leaf axils.

Triodanis perfoliata flowers

Upper flowers - Chasmogamous, fertile. Corolla purple, (rarely white), 5-lobed,  +1.5cm broad. Lobes to 9mm long, with few stiff hairs on midvein below, otherwise glabrous. Stamens 5. Filaments flattened and expanded at base and divided above. Anthers yellow, 2mm long. Style 1, 7mm long, clavate, purple at apex, pubescent. Stigma 3-lobed. Ovary inferior. Fruit many seeded.  Calyx 5-lobed. Tube to +/-4mm long. Lobes attenuate, 6-7mm long, 2mm broad at base, glabrous with stigillose margins.

Triodanis perfoliata flowerChasmogamous flower close-up.

Lower flowers - Cleistogamous, fertile. Calyx tube to 5mm long. Calyx lobes to 3mm long.

Flowering - April - August.

Habitat - Waste places, disturbed sites, pastures, prairies, roadsides, railroads.

Origin - Native to U.S.

Other info. - This species is common and unmistakable because of the perfoliate leaves. The lower (cleistogamous) flowers are fertile but produce very little viable seed. The upper(chasmogamous) flowers produce much more viable seed.
The typical form of the plant is form perfoliata, having the blue flowers. Steyermark also lists a white flowered form, form alba (Voigt) Steyermark.
A more frequent synonym for the species is Triodanis perfoliata (L.) Nieuw.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 5-24-03, and in Auburn, AL., 5-6-05.