Diggin’ In: Wild petunia provides pretty summer flowers

June 6, 2016

Petunias produce pretty summer flowers, and the native Carolina wild petunia is no exception.

The wild petunia, scientifically known as Ruellia caroliniensis, is a Coastal Plain native perennial that returns each year from previous locations and from self-seedings, according to Helen Hamilton, past president of the John Clayton Chapter, Virginia Native Plant Society, and retired biology teacher living in Williamsburg, Va.

The petunia blooms May through September, with each flower lasting only a day but followed by other blooms in quick succession. As the flowers fade, seeds form and eject themselves into the air, meaning baby plants soon appear anywhere and everywhere.

Best of all, wild petunia is not fussy about where it grows — any soil is OK, full sun or part shade works and drought doesn’t deter it.

"The lavender-blue, one-inch flowers are a bright spot in the garden, growing only a foot or so tall on somewhat straggly stems," says Hamilton.

"This plant’s dark green lance-shaped leaves look wonderful alongside orange butterfly milkweed, jewelweed and bluestar."

The flowers benefit pollinators, including large bees. Carolina wild petunia is also host to the common buckeye butterfly, giving its caterpillars leaves to feed on while they develop into adults.

A relative of Carolina wild petunia, Mexican petunia (Ruellia brittoniana) is native to Mexico. Listed as invasive in several states, the aggressive annual — or perennial further south — and its popular cultivar called Purple Showers is sold along with other cultivars, including the poplar Wave petunias.

The garden petunia (Petunia x hybrida) is not closely related, and is actually a member of the potato family, which includes tobacco, tomatoes and chili peppers, according to Hamilton.

Carolina wild petunia is sometimes sold in garden centers, and is often found in native plant sales or online nurseries. Deer do not bother the fuss-free plant.


Common buckeye butterflies are easy to spot — brown wings bordered with cream, yellow or orange and several prominent eyespots, which may help protect them from hungry birds, according to Hamilton.

On the ground, common buckeye, or Junonia coenia, usually rests with open wings on bare ground or low plants, especially mountain mints, plantains, asters, tickseed sunflower, sedum and dogbane.

"Since adults live only a few days, usually no more than 10, they are very interested in mating," says Hamilton.

"Male buckeyes perching on low ground are watching for females; they will chase away another male buckeye and encourage a female buckeye to land where mating can occur."

After mating, female buckeyes deposit just one tiny whitish egg on a leaf bud or the upper side of a leaf. As they progress through four moltings, the larvae (caterpillars) are black with rows of orange and cream spots from which emerge short hairy black spines, continues Hamilton. The head is also black with an orange spot and two short black spines on top. Larvae transform into pupae where metamorphosis is completed — May through October, two to three broods appear.

Female buckeyes lay their eggs only on the plants that the developing caterpillars will eat. In Hampton Roads, Wild petunia (Ruellia caroliniensis) is a favorite host plant along with smooth beardtongue (Penstemon digitalis) and blue vervain (Verbena hastata), says Hamilton.



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