North America Native Plant

Roundleaf Thoroughwort

Botanical name: Eupatorium rotundifolium var. ovatum

USDA symbol: EUROO

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Eupatorium pubescens Muhl. ex Willd. (EUPU11)  âš˜  Eupatorium rotundifolium L. ssp. ovatum (Bigelow) J.D. Montgom. & Fairbrothers p.p. (EUROO2)   

Roundleaf Thoroughwort: A Native Gem for Late-Season Pollinators If you’re looking for a native plant that brings life to your garden when many others are winding down for the season, roundleaf thoroughwort (Eupatorium rotundifolium var. ovatum) might just be your new best friend. This unassuming perennial forb packs a punch ...

Roundleaf Thoroughwort: A Native Gem for Late-Season Pollinators

If you’re looking for a native plant that brings life to your garden when many others are winding down for the season, roundleaf thoroughwort (Eupatorium rotundifolium var. ovatum) might just be your new best friend. This unassuming perennial forb packs a punch when it comes to supporting pollinators during the crucial late summer and fall months.

What Makes Roundleaf Thoroughwort Special?

Roundleaf thoroughwort is a true native of the eastern United States, calling home to 24 states from Maine down to Florida and stretching west to Ohio and Louisiana. As a member of the aster family, this hardy perennial has been quietly supporting local ecosystems for centuries, and it’s ready to do the same in your garden.

Don’t let the name fool you – while it’s called roundleaf, the variety ovatum actually has more oval-shaped leaves. This plant is what botanists call a forb, which simply means it’s a non-woody flowering plant that dies back to the ground each winter and returns fresh each spring.

Why Your Garden (and Local Wildlife) Will Love It

Here’s where roundleaf thoroughwort really shines: it’s a pollinator magnet during late summer and early fall when many other flowering plants have called it quits. The small, creamy-white flowers cluster together in flat-topped displays that butterflies, bees, and other beneficial insects absolutely adore. It’s like setting up a buffet table just when your pollinator friends need it most.

Beyond its wildlife benefits, this plant is refreshingly low-maintenance. Once established, it’s quite drought tolerant and doesn’t demand much fussing from busy gardeners. It naturally fits into wildflower meadows, woodland edges, and native plant gardens where it can spread and naturalize without becoming aggressive.

Growing Roundleaf Thoroughwort Successfully

The good news is that roundleaf thoroughwort is fairly easygoing about its growing conditions:

  • Sunlight: Full sun to partial shade (though it blooms best with at least 6 hours of sun)
  • Soil: Adaptable to various soil types, from sandy to clay
  • Water: Moderate water needs; drought tolerant once established
  • Climate: Hardy in USDA zones 4-9

Planting and Care Tips

Getting started with roundleaf thoroughwort is straightforward. Plant it in spring after the last frost, giving each plant about 18-24 inches of space to spread. While it can handle some drought, regular watering during its first growing season will help it establish a strong root system.

This plant typically reaches 2-4 feet tall and spreads slowly through underground rhizomes, making it perfect for naturalizing without taking over your entire garden. In late fall, you can cut the stems back to ground level, or leave them standing for winter interest and to provide seeds for birds.

Design Ideas and Garden Roles

Roundleaf thoroughwort works beautifully in several garden settings:

  • Native plant gardens where it can mingle with other regional species
  • Pollinator gardens as a late-season nectar source
  • Naturalized meadow areas where it can spread freely
  • Woodland edges or transition zones between lawn and forest
  • Rain gardens (though specific wetland status varies by location)

The Bottom Line

If you’re building a garden that truly supports local wildlife while requiring minimal maintenance, roundleaf thoroughwort deserves a spot on your plant list. It may not be the showiest plant in your garden, but its timing is impeccable – providing crucial late-season resources when pollinators need them most. Plus, there’s something deeply satisfying about growing a plant that’s been thriving in your region for thousands of years.

Just remember to source your plants or seeds from reputable native plant nurseries to ensure you’re getting the real deal. Your local butterflies will thank you come September!

Roundleaf Thoroughwort

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

Asterales

Family

Asteraceae Bercht. & J. Presl - Aster family

Genus

Eupatorium L. - thoroughwort

Species

Eupatorium rotundifolium L. - roundleaf thoroughwort

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