Virginia Tech Weed Identification Guide

Common Venus' Looking-glass: Triodanis perfoliata

Weed Description:  An erect winter or summer annual with leaves that clasp the stem and purple flowers.  Common Venus' looking-glass is primarily a weed of landscapes, lawns, turfgrass, and occasionally pastures and hay fields.  This weed is found throughout the United States.

Stems:  Erect, branched, hairy, reaching as much as 1 1 /2 feet in height.

Leaves:  Leaves are rounded to oval in outline, distinctly clasping the stem to the point that they appear to completely enclose the stem.  Leaves range from 1/4 to 1 1/2 inches in length and from 6 to 25 mm in width.  Leaf margins are usually slightly serrated or toothed.

Roots: A fibrous root system.

Flowers:  Occur in clusters of 1 to 3 in the positions between the leaves and stems.    Flowers consist of 5 purple petals that are collectively approximately 3/4 inch wide.  Flowers do not occur on flower stalks (peduncles).

Fruit:   A long, narrow capsule containing many very small (0.5 mm long), reddish seed.

Identifying Characteristics:   The round or oval leaves that almost completely encircle the stem and the distinctive purple flowers are both characteristics that help to distinguish common Venus' looking-glass from most other weeds.