Sunday, May 15, 2016
Venus' Looking-glass - Triodanis perfoliata
Venus' looking-glass (Triodanis perfoliata) is an annual member of the bluebell family (Campanulaceae) and common to disturbed sites and roadsides throughout the northern two-thirds of Florida and nearly all of Canada and the U.S. Its natural range occurs south to Argentina and it is naturalized in China, Korea and Australia.
The common name likely refers to the shiny lens-shaped seeds which can act like a mirror, though they are too tiny to see without some magnification. The stem is unbranched and reaches a mature height of 6-12 inches by bloom time. The stem is deeply furrowed and lined with small white "hairs." The leaves are alternate along the stem until they reach the top - where they become opposite each other. Each leaf is heart-shaped (chordate), lime green in color, slightly toothed along the margin and clasp the stem. Flower buds form (generally three in number) in each of the leaf axils.
Flowering occurs for about a month in late spring to summer. Though 1-3 buds are formed at each axil, only one is generally open at a time. The blooms are deep violet to purple in color, and quite attractive, though only about 1/2 inch in diameter. Each is composed of five petals which generally open more flat than the flowers pictured above. The throat is lighter in color and the white-colored, prominent reproductive parts emerge from the base. Pollinated flowers (though the lower ones generally are self pollinating - cleistogamous) ripen to brown seed capsules in early fall. Like other members of this family, they explode when ripe and scatter the many seeds away from the parent.
Though attractive, the annual nature and small stature of this wildflower limit its potential in cultivation. It is only rarely offered and difficult to maintain in a typical landscape setting. It thrives in poor soil and open conditions, and does not tolerate being overly crowded by other plants. It is recorded that the Cherokee Nation used a tincture made from its roots to treat stomach ache.