The Queen's wreath (Petrea volubilis Linnaeus) is a woody vine native to Mexico and Central America. It makes a beautiful tropical substitute for wisteria (Wisteria sinensis).

Petrea are classified in the Verbenaceae or verbena family. There are an estimated 30 species in the American tropics. Queen's wreath leaves have a rough surface giving the plant another common name, the sandpaper vine.

The flowers are amethyst to deep purple, surrounded by showy lilac calices (calyx, the whorl of sepals). After the flowers have dropped, the calices fade to a silvery brown. When the seed ripens, the calyx breaks from the plant and 'helicopters' on the wind.

Linnaeus named Petrea in honor of Robert James Petre (b. 1713, d. 1742), the Eighth Lord Petre of Ingatestone Hall in Essex. Petre was a patron of botany. Although he died very young, Petre must have made a favorable impression on Linnaeus.