Plant DetailShow Menu

Britton's Wild Petunia Ruellia simplex

Previously known as:

  • Ruellia brittoniana
  • Ruellia coerulea
  • Ruellia malacosperma
  • Ruellia spectabillis
  • Ruellia tweedyana
Phonetic Spelling
roo-EL-ee-yuh SIM-plecks
Description

Mexican petunia is an ornamental herbaceous perennial of the Acanthaceae family. It is shrubby with a woody base and somewhat aggressive. The plant typically grows to 3 to 4 feet tall in the wild, but only to 2 or 3 feet tall in gardens. It has linear, dark green leaves that may be tinged with purple, and measure 6 to 12 inches long and 0.75 inches wide. The flowers are petunia-like, lavender to violet, and only last one day. It is hardy in zones 8 through 10 and is evergreen in warm climates. It is an excellent annual flowering plant in colder climates.

This plant is native to Central and South America and the Caribbean. Mexican petunia plants will spread by rhizomes and self-seeding in the garden and have aggressively naturalized in South Carolina, Texas, and Hawaii. Although this plant has excellent flowering attributes, this species is currently listed as a Category One invasive species by the Florida Exotic Pest Plant Council (FEPPC) because it has been found to invade natural areas and displace native flora in the State of Florida.

The genus name, Ruellia, honors a French herbalist and physician, Jean de la Ruelle. The epithet, simplex, references its simple leaves. There has been confusion over the correct epithet, and it has had several different names over the years. Ruellia simplex is preferred since that was the original name given when it was first described in Cuba in 1870.

Mexican petunia prefers medium to wet soil that is fertile, well-drained, and flowers best in full sun.  Mexican petunia is a tolerant plant. It is willing to grow in boggy wet conditions, in soil that varies from wet to dry, and tolerates high heat and humidity. Once established, the plant does well in drought conditions. It is seldom damaged by deer. 

Cut back stems after flowering to encourage new flowers. They are easily propagated by cuttings, division, and seed. Keep in mind that some cultivars are sterile ('Purple Showers'), in which case they may be spread by rhizomes.

Mexican Petunia is very popular and may be grown in bog gardens, on the margins of ponds, and in beds and borders. It may also be used as a container plant on patios or as a houseplant. The vibrant colored flowers make this an attractive plant that is tolerant of a variety of urban conditions. Just remember that this plant reseeds easily, and removal may prove challenging from the home landscape.

Seasons of Interest:

Bloom:  Summer and Fall    Foliage:  Summer, Fall, and Winter in warm climates

Quick ID Hints:

  • 3- to 4-foot-tall herbaceous perennial with green or purple stems
  • lance-shaped, glossy, green leaves
  • petunia-like lavender flowers, blooming summer through the fall
  • fruits are bean-like pods that contain 4 to 28 seeds

Insects, Diseases, and Other Plant Problems: Mexican Petunia has no serious insect or disease problems; however, it can be difficult to eradicate once it is established. The plant's self-seeding and rhizomes contribute to its aggressiveness. The seeds are explosively expelled from their capsules and can persist in the soil.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.

 

Profile Video:
See this plant in the following landscape:
Cultivars / Varieties:
  • 'Chi Chi'
  • 'Katie'
    slightly salt tolerant
  • 'Purple Showers'
'Chi Chi', 'Katie', 'Purple Showers'
Tags:
#showy flowers#full sun tolerant#heat tolerant#drought tolerant#fall flowers#perennials#purple flowers#weedy#pond margins#fast growing#aggressive#summer flowers#deer resistant#herbaceous perennials#long bloom time#reseeds#border planting#self-seeding#humidity tolerant#wet soils tolerant#annual#erect#landscape plant sleuths course#boggy sites
 
Cultivars / Varieties:
  • 'Chi Chi'
  • 'Katie'
    slightly salt tolerant
  • 'Purple Showers'
'Chi Chi', 'Katie', 'Purple Showers'
Tags:
#showy flowers#full sun tolerant#heat tolerant#drought tolerant#fall flowers#perennials#purple flowers#weedy#pond margins#fast growing#aggressive#summer flowers#deer resistant#herbaceous perennials#long bloom time#reseeds#border planting#self-seeding#humidity tolerant#wet soils tolerant#annual#erect#landscape plant sleuths course#boggy sites
  • Attributes:
    Genus:
    Ruellia
    Species:
    simplex
    Family:
    Acanthaceae
    Life Cycle:
    Perennial
    Recommended Propagation Strategy:
    Division
    Seed
    Stem Cutting
    Country Or Region Of Origin:
    Caribbean, Central and South America, Mexico
    Distribution:
    Native: Argentina, Bolivia, Brazil, Costa Rica, Dominican Republic Ecuador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Panama, Paraguay, Peru, Puerto Rica, Trinidad-Tobago, Uruguay, and the United States--FL, LA, and TX. Introduced: United States--Al, GA, HI, MS, SC; Bangladesh, Bermuda, Cook Island Galapagos, Gambia, Myanmar, South China Sea, and Venezuela
    Wildlife Value:
    Attracts butterflies.
    Particularly Resistant To (Insects/Diseases/Other Problems):
    deer resistant
    Dimensions:
    Height: 3 ft. 0 in. - 4 ft. 0 in.
    Width: 2 ft. 0 in. - 3 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Annual
    Perennial
    Habit/Form:
    Erect
    Mounding
    Multi-stemmed
    Growth Rate:
    Rapid
    Maintenance:
    Medium
    Texture:
    Coarse
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Partial Shade (Direct sunlight only part of the day, 2-6 hours)
    Soil Texture:
    Clay
    High Organic Matter
    Loam (Silt)
    Sand
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Good Drainage
    Moist
    Occasionally Wet
    Available Space To Plant:
    3 feet-6 feet
    NC Region:
    Coastal
    USDA Plant Hardiness Zone:
    8b, 8a, 9b, 9a, 10b, 10a
  • Fruit:
    Fruit Type:
    Capsule
    Fruit Length:
    < 1 inch
    Fruit Description:
    The fruit is a cylinder-like capsule or bean-like pod measuring 1-inch long. The capsule contains 4 to 28 seeds that explosively dehisce mature seeds in all directions.
  • Flowers:
    Flower Color:
    Purple/Lavender
    Flower Inflorescence:
    Cyme
    Solitary
    Flower Value To Gardener:
    Long Bloom Season
    Showy
    Flower Bloom Time:
    Fall
    Summer
    Flower Shape:
    Trumpet
    Tubular
    Flower Size:
    1-3 inches
    Flower Description:
    Five lobed, petunia-like, lavender to violet flowers bloom from the upper leaf axils in loose purple-stemmed clusters. Flowers freely but each flower blooms for only one day. Flowers typically bloom from May to September.
  • Leaves:
    Leaf Color:
    Green
    Purple/Lavender
    Leaf Arrangement:
    Opposite
    Leaf Shape:
    Lanceolate
    Linear
    Leaf Margin:
    Entire
    Undulate
    Hairs Present:
    No
    Leaf Length:
    > 6 inches
    Leaf Width:
    < 1 inch
    Leaf Description:
    Elongated, linear, willow-like, dark green leaves (6 to 12 inches long) that are often tinged with purple. Evergreen for winter interest.
  • Stem:
    Stem Color:
    Green
    Purple/Lavender
    Stem Is Aromatic:
    No
    Stem Description:
    The stems are green or purple and measure up to 39 inches tall. The plant branches from the ground into several woody-based stems.
  • Landscape:
    Landscape Location:
    Container
    Houseplants
    Patio
    Pond
    Landscape Theme:
    Pollinator Garden
    Rain Garden
    Rock Garden
    Design Feature:
    Border
    Attracts:
    Butterflies
    Hummingbirds
    Resistance To Challenges:
    Deer
    Drought
    Heat
    Humidity
    Wet Soil
    Problems:
    Weedy