Non-native Plants

Paraguayan Starbur

Acanthospermum australe

USDA symbol: ACAU2

annual forb

Hawaii: non-native, naturalized
Lower 48 states: non-native, naturalized

If you’ve stumbled across small, prickly seed heads clinging to your socks after a walk through a weedy field, you might have encountered Paraguayan starbur (Acanthospermum australe). This unassuming little plant has quite the talent for getting around, but before you consider adding it to your garden, let’s dive into ...

Paraguayan Starbur: A Weedy Wildflower You’ll Probably Want to Skip

If you’ve stumbled across small, prickly seed heads clinging to your socks after a walk through a weedy field, you might have encountered Paraguayan starbur (Acanthospermum australe). This unassuming little plant has quite the talent for getting around, but before you consider adding it to your garden, let’s dive into what makes this South American native tick—and why you probably don’t want it ticking in your backyard.

What Is Paraguayan Starbur?

Paraguayan starbur is a non-native annual or perennial forb that originally hails from South America, particularly Paraguay, Argentina, and southern Brazil. As a forb, it’s an herbaceous plant without woody stems, staying relatively close to the ground and producing those characteristic burr-like seed heads that give it its common name.

You might also see this plant listed under its synonyms Acanthospermum xanthioides or Melampodium australe in older gardening references, though these names are less commonly used today.

Where You’ll Find It

This adaptable little plant has made itself at home across a surprising number of U.S. states, including Alabama, Arkansas, Florida, Georgia, Hawaii, Louisiana, Massachusetts, Mississippi, New York, North Carolina, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, and Virginia. It’s particularly well-established in the Southeast and has even island-hopped its way to Hawaii.

  • Species observed
  • No observations

Should You Grow Paraguayan Starbur?

Here’s where we need to have an honest conversation: Paraguayan starbur is generally considered a weedy species rather than an ornamental plant. While it does produce small yellow flowers that might catch your eye, this plant is more likely to be something you’re trying to manage rather than cultivate.

The Weedy Reality

Paraguayan starbur has several characteristics that make it less than ideal for most gardens:

  • Produces spiny, clinging seed heads that stick to clothing and animal fur
  • Tends to spread aggressively in suitable conditions
  • Generally considered more of a pest than an ornamental
  • Can compete with more desirable native plants

Better Native Alternatives

Instead of Paraguayan starbur, consider these native alternatives that offer similar growing conditions but with greater ecological benefits:

  • Native sunflowers (Helianthus species)
  • Black-eyed Susan (Rudbeckia species)
  • Native asters (Symphyotrichum species)
  • Tickseed (Coreopsis species)

These native alternatives will provide better support for local wildlife, including pollinators and birds, while adding genuine ornamental value to your landscape.

If You’re Stuck With It

Sometimes plants choose us rather than the other way around. If Paraguayan starbur has already established itself in your area, here’s what you should know:

Growing Conditions: This adaptable plant thrives in full sun and tolerates a wide range of soil conditions. It’s generally hardy in USDA zones 8-11, though it may behave as an annual in cooler regions.

Management Tips:

  • Remove plants before they set seed to prevent spread
  • Hand-pull small infestations when soil is moist
  • Maintain healthy native plant communities to outcompete weedy species
  • Consider professional consultation for large infestations

The Bottom Line

While Paraguayan starbur isn’t necessarily harmful, it’s not the best choice for intentional cultivation. Its weedy nature and tendency to produce clinging seed heads make it more of a garden challenge than a garden asset. Your time and garden space are better invested in native plants that will support local ecosystems while providing genuine ornamental value.

Remember, the best gardens work with nature rather than against it, and choosing plants that belong in your local ecosystem is always the way to go!

Acanthospermum australe is also known as...

Often we refer to plants by their common names. When shopping for plants the scientific name is the best way to positively identify the plant species you desire. But some plants have more than one name! While it doesn't happen often, nurseries might display one name while you're searching for another. Acanthospermum australe is also known as:

Acanthospermum xanthioides DC. | USDA symbol: ACXA
Melampodium australe | USDA symbol: MEAU

Why do some plants have more than one name? Over time plant species may be renamed for a few reasons:

  1. Botanists in different regions named the same plant without knowing it had already been classified.
  2. A species was reclassified after scientific advances in, for example, DNA analysis.
  3. Slight variations within a species are sometimes mistakenly identified as entirely new species.

Classification

Group: Dicot
Kingdom: Plantae - Plants
Subkingdom: Tracheobionta - Vascular plants
Superdivision: Spermatophyta - Seed plants
Division: Magnoliophyta - Flowering plants
Class: Magnoliopsida - Dicotyledons
Subclass: Asteridae
Order: Asterales
Family: Asteraceae Bercht. & J. Presl - Aster family
Genus: Acanthospermum Schrank - starbur

Species: Acanthospermum australe (Loefl.) Kuntze - Paraguayan starbur

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