North America Non-native Plant

Britton’s Wild Petunia

Botanical name: Ruellia caerulea

USDA symbol: RUCA19

Life cycle: perennial

Habit: subshrub

Native status: Non-native, reproduces and persists in the wild in Hawaii âš˜ Non-native, reproduces and persists in the wild in the lower 48 states âš˜ Non-native, reproduces and persists in the wild in Pacific Basin excluding Hawaii âš˜ Non-native, reproduces and persists in the wild in Puerto Rico âš˜ Non-native, reproduces and persists in the wild in the U.S. Virgin Islands  

Synonyms: Ruellia brittoniana Leonard (RUBR)  âš˜  Ruellia malacosperma sensu Small, non Greenm. (RUMA18)  âš˜  Ruellia simplex C. Wright (RUSI7)  âš˜  Ruellia tweediana auct. non Griseb. (RUTW)   

Britton’s Wild Petunia: A Non-Native Bloomer for Wet Spots Looking for a purple-flowered perennial that thrives in those soggy spots where other plants fear to tread? Meet Britton’s wild petunia (Ruellia caerulea), a South American native that has made itself quite at home in the warmer regions of the United ...

Britton’s Wild Petunia: A Non-Native Bloomer for Wet Spots

Looking for a purple-flowered perennial that thrives in those soggy spots where other plants fear to tread? Meet Britton’s wild petunia (Ruellia caerulea), a South American native that has made itself quite at home in the warmer regions of the United States. While it’s not a true petunia despite its common name, this adaptable perennial brings reliable color to challenging wet areas in the garden.

What Is Britton’s Wild Petunia?

Britton’s wild petunia is a perennial forb – essentially a non-woody flowering plant that comes back year after year. Originally from South America, particularly Argentina and southern Brazil, this plant has established itself across the southeastern United States and beyond. You might also see it listed under several scientific synonyms, including Ruellia brittoniana or Ruellia simplex, which can make plant identification a bit tricky!

Where Does It Grow?

This adaptable plant has spread far from its South American origins and now grows in Alabama, Florida, Georgia, Hawaii, Louisiana, Mississippi, South Carolina, Texas, and various U.S. territories including Guam, Puerto Rico, and the Virgin Islands. It’s classified as non-native in all these locations, having been introduced and now reproducing on its own in the wild.

Garden Appeal and Characteristics

What makes Britton’s wild petunia appealing to gardeners? Here are its standout features:

  • Purple-blue tubular flowers that bloom from spring through fall
  • Thrives in wet conditions where many plants struggle
  • Low-maintenance once established
  • Attracts butterflies, hummingbirds, and bees
  • Forms spreading colonies that work well as ground cover

Growing Conditions and Care

If you’re considering adding this plant to your landscape, here’s what it needs to thrive:

  • Climate: Hardy in USDA zones 8-11
  • Light: Full sun to partial shade
  • Soil: Moist to wet soils; tolerates flooding
  • Water: Consistent moisture is key
  • Maintenance: Minimal care required once established

The plant’s wetland status varies by region – it’s classified as facultative in most areas, meaning it can grow in both wet and drier conditions, though it clearly prefers the wetter end of the spectrum.

Ideal Garden Settings

Britton’s wild petunia works best in:

  • Rain gardens and bioswales
  • Pond or stream edges
  • Low-lying areas that collect water
  • Informal or naturalized garden styles
  • Areas where you want low-maintenance ground cover

Should You Plant It?

While Britton’s wild petunia isn’t listed as invasive, it’s worth considering that as a non-native species, it doesn’t provide the same ecological benefits as indigenous plants. If you’re drawn to its purple blooms and wet-soil tolerance, you might also consider these native alternatives that offer similar benefits while supporting local ecosystems:

  • Blue flag iris (Iris virginica) for wet areas
  • Wild bergamot (Monarda fistulosa) for purple blooms
  • Cardinal flower (Lobelia cardinalis) for hummingbird appeal
  • Blue vervain (Verbena hastata) for butterfly attraction

The Bottom Line

Britton’s wild petunia can be a reliable performer in challenging wet spots where you want consistent color and minimal fuss. While it’s not native to North America, it’s also not considered invasive in most areas where it grows. If you choose to plant it, you’ll get a hardy perennial that provides nectar for pollinators and adds purple blooms to your landscape from spring through fall. Just remember to consider native alternatives first – they often provide greater benefits to local wildlife and help preserve regional plant communities.

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" matching plants to their ideal growing conditions, so they'll thrive with less work and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection is. While tags list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. Surprisingly, many popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. Also, it helps you make smarter gardening choices and grow healthy plants with less care and feeding, saving you time, frustration, and money while producing an attractive garden with greater ecological benefits.

Regions
Status
Moisture Conditions

Atlantic and Gulf Coastal Plain

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Caribbean

FACW

Facultative Wetland - Plants with this status usually occurs in wetlands but may occur in non-wetlands

Eastern Mountains and Piedmont

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Great Plains

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Hawaii

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Britton’s Wild Petunia

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Scrophulariales

Family

Acanthaceae Juss. - Acanthus family

Genus

Ruellia L. - wild petunia

Species

Ruellia caerulea Morong - Britton's wild petunia

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA