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| Ruellias flower throughout the heat of summer. |
Are you looking for native, non-aggressive flowering plants that are perfectly adapted to our central Texas limestone soils and extreme summer heat? Then look no further than some of our local species of Ruellia, also informally but incorrectly called wild petunias. They include Drummond’s Ruellia (Ruellia drummondiana), Hairy Ruellia (Ruellia humilis), Metz’s Ruellia (Ruellia metziae), and Violet Ruellia (Ruellia nudiflora).
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| Drummond's Ruellia |
A Texas endemic, Drummond’s Ruellia has ovate, fine-haired leaves and purple to dark lavender stalkless (sessile) blooms arising from the leaf axils (axillary). It is prominent on the Edwards Plateau and in and around Austin, and blooms from June to November. Hairy Ruellia, also called Fringeleaf Wild Petunia, has conspicuously hairy oval leaves with pointed tips and hairy margins, and purple to pale purple axillary, sessile blooms. It is highly drought-tolerant and is widespread in open prairies on limestone soil, where it blooms from May to September.
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| Hairy Ruellia |
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| Metz's Ruellia |
Metz’s Ruellia or White Ruellia is distinct in that it features uncommonly white or pale-throated stalked (peduncled) blooms in a branched structure (panicle) at the tops of stems (terminal), and oval leaves on long leaf bases (petioles). It thrives on limestone outcrops and in open woods, and blooms from June to August. Violet Ruellia, also called Common Wild Petunia, is one of the most ubiquitous of all these species, with a similar arrangement of peduncled blooms in a panicle on the terminal ends of stems, but the blooms are purple to violet-blue. The leaves are oval, smooth and essentially hairless (glabrous) with somewhat wavy margins, and the blooms occur from April to October.
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| Violet Ruellia |
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| Mexican Petunia (non-native) |
Unlike the invasive, non-native Mexican Petunia (Ruellia simplex) that is sold in many nurseries, these resilient native species are well-behaved. They provide a bounty of successive summer blooms while other flowering plants are wilting in the heat. Their flowers open in the morning and fall off by evening, and they can be correctly identified by the structure of the inflorescence (axillary or panicled), leaf texture (waxy, hairy, or fringe on margins) and leaf shape (ovate, oval, or lance-shaped). The Hairy Ruellia and Violet Ruellia species are also host plants for Common Buckeye and White Peacock butterflies.
The genus Ruellia was named after a French botanist and physician, Jean Ruelle, who lived during the Renaissance Period. He was noted for his 1536 publication in Paris of De Natura Stirpium, a Renaissance treatise on botany, which included detailed descriptions not only of a plant species' habit and habitat, but also the smell and taste of each.
