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American Burnweed (Erechtites hieraciifolius (L.) Raf. ex DC.)

Also known as fireweed, pilewort; also classified as Erechtites hieraciifolia (Spelling Error), Erechtites hieracifolia (Spelling Error), Senecio hieraciifolius L..

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American Burnweed
Photo © Michael Kummer, Public Domain.


A tall annual plant native to North America. Introduced on other continents, where it is often considered an invasive species. Widespread in humid parts of Eastern North America. From a distance, its flowers look a bit like buds that never open.

Range - Expand

Native or Not Present
Introduced or Not Present

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.

Description & Identification

This plant's size is highly variable, depending on moisture, light levels, and nutrient availability. Mature plants can range from 1cm to 2.5m (8ft) in height.


Favors moist areas with exposed soil, in sun to light shade, but receiving some direct sunlight. Found in a range of soil types, including sandy, clay, loamy, rocky, and gravely soils. Tolerates salinity up to 0.5%, and a wide range of pH, including both acidic and alkaline soils.

Frequently found where fire has occurred, but does not depend on fire and also occurs in numerous human-altered habitats where it benefits from vegetation removed by mowing, herbicide use, and weeding. Found in roadsides, along railroads, in agricultural land, and gardens. Also frequently colonizes ponds, lakes, and wetlands following drainage or a drop in water level, which can occur in response to drought, human activity, or beaver dams.

Life Cycle

This plant is a summer annual.

It sprouts from seed in late spring to early summer. Early sprouting plants may grow for a short time as a basal rosette, but it usually begins growing upright rather soon. It usually does not branch until it flowers, although it will branch in response to being cut or having its top removed or broken off. It usually grows in height continually until flowering.

Flowers are inconspicuous and primarily wasp-pollinated. Seeds are wind-dispersed, often carried over long distances, and usually germinate only after cold dormancy.

It is not known how long this species persists in the seed bank, and there is conflicting evidence on this topic. There has been evidence of high germination rates in seeds as old as 8 years, but in many circumstances, seeds seem to originate from newer, wind-dispersed seeds rather than seeds persisting in the soil.

Ecologically, this plant is an early-successional plant, and its populations are usually short-lived in the absence of repeated disturbance.

Faunal Associations

Larvae of the moth Palthis asopialis, which eats many different species, has been reported feeding on this plant. The larvae of the moths Phyllocnistis insignis and Phytobia maculosa feed as a leaf miner on this and a few closely-related plants. The larvae of the flies Liriomyza sativae and Liriomyza trifolii also eat this plant, among many others.

The generalist Tarnished Plant bug Lygus lineolaris also feeds on this plant. Gall midges (Neolasioptera sp.) have also been reported on this plant.

The aphid Brachycaudus helichrysi, best-known as a pest of plum trees, also has been recorded feeding on this plant.

The flowers primarily attract wasps, but occasionally other pollinators.


This plant has developed resistance to the herbicide 2,4-D.

Erechtites hieraciifolius (American Burnweed) | USDA PLANTS Database (About This Site)

Erechtites hieraciifolius | Go Botany (About This Site)

Erechtites hieraciifolius (American burnweed) | CABI Invasive Species Compendium (About This Site)

Senecio hieraciifolius | Biota of North America Project (BONAP) (About This Site)

Erechtites hieraciifolius | NatureServe Explorer (About This Site)

Erechtites hieraciifolius | Flora of North America (About This Site)

Erechtites hieraciifolius | Missouri Plants (About This Site)

American Burnweed | Maryland Biodiversity Project (About This Site)

Erechtites hieraciifolius (Pilewort) | Minnesota Wildflowers (About This Site)

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Photo © , CC BY-SA 4.0.
Photo © , CC BY-SA 4.0.
Photo © , CC BY-SA 4.0.
Photo © , CC BY-SA 4.0.
Photo © Michael Kummer, Public Domain.