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Annual Fleabane (Erigeron annuus (L.) Pers.)

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Annual Fleabane

Summary

A common annual or biennial native to Eastern North America.

Range - Expand

LegendColor
Native
Introduced
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

E. annuus is highly variable in characteristics, including size and growth habit and bloom time.

To distinguish from other Erigeron species, it often, but not always, has more leaves and larger leaves than other fleabane species. Its leaves do not clasp the stem at the base.

Similar Plants

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Daisy Fleabane (Erigeron strigosus)
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Habitat

Found in prairies, pastures, abandoned fields, along roadsides and railroads, disturbed ground in open woods, and waste areas. In the humid east, more common in anthropogenic habitats but occasionally found in wild habitats as well, where it is primarily a pioneer species. In the west of its range it is found in more stable grassland habitats as a longer-term resident, although it still favors locally-disturbed sites.

Prefers full to partial sun and moist to mesic conditions. Tolerates a wide variety of conditions, including soil with significant amounts of clay and/or rock. Usually limited to sites that have experienced recent disturbance.

Life Cycle

This species is an annual-to-biennial plant that is strictly asexual, reproducing only by apomixis or agamospermy, clonal reproduction through seeds.

Although its name suggests an annual lifecycle, this species is opportunistic and has a flexible life-cycle. Seeds can germinate at various times, although they most frequently germinate in late summer.

Plants establishing in spring and in favorable conditions typically grow as summer annuals, growing upright, flowering, producing seed, and dying. Plants that establish in conditions that slow their growth, including greater shade, less moisture, and less fertile soil, may overwinter and bloom in their second year. A majority of plants, germinating in late summer to early fall, grow as winter annuals and bloom in the following year. Overwintering plants maintain an evergreen basal rosette of leaves in mild winters, and are deciduous in colder winters.

Flowering time is wildly variable, ranging from May through November, although earlier times are more common. Typically, well-established overwintering plants make up the majority of plants, and most of these plants will bloom closer to May. Drought stress or top-kill such as from herbivory or mowing, followed by a period of favorable conditions, can sometimes delay flowering.

As this plant does not rely on cross-pollination to reproduce, it does not need to time blooms to coincide with other plants.

Faunal Associations

In spite of reproducing only asexually, the flowers produce nectar and pollen, and attract a variety of small pollinators, including various bees, wasps, flies, and some bugs and beetles. There are also numerous insects that eat the foliage of this plant.

Control

This species has been introduced in western North America and some people may want to remove it as it is not native there. It has become a highly invasive plant in parts of the world, including East Asia, although it has yet to exhibit this effect on the ecosystems in western North America.

This species has high seed production and can be difficult to remove from suitable sites if it is allowed to go to seed. It is easiest to learn how to identify plants before they flower, as seeds can be produced and dispersed quickly after flowering. Plants can then be uprooted.

Because its seeds are dispersed in the wind, this species will continue to reappear as long as there are nearby populations.

Large infestations can sometimes be controlled by a change in mowing regime. In areas where this species grows taller than the native vegetation, a few carefully-timed mows during the time period where this species is growing upright can eliminate it from a site, or at least greatly reduce seed production. However, care must be taken that such mowing is not more disruptive to native vegetation. In other cases, avoiding mowing an area at all may eliminate it if it leads to it being out-competed by taller, native vegetation. Often, mowing was the disturbance that allowed this species to take hold, so avoiding mowing areas at risk of colonization by this species can prevent it from establishing.

Uses

This species is occasionally used in wildlife plantings and gardens. It transplants readily, when at the basal rosette stage of growth. More often, it is not intentionally planted, but rather, left in place by ecologically-minded gardeners when it seeds into their garden.

In gardens it is valued for its attractive flowers and widespread adaptability. Its use can be limited by its tendency to spread aggressively in some garden settings.

It can also be used in ecological restoration plantings, where it often competes favorably against invasive plants.

Erigeron annuus (Annual Fleabane) | Illinois Wildflowers (About This Site)

Erigeron annuus (Annual Fleabane) | USDA PLANTS Database (About This Site)

Erigeron annuus | Go Botany (About This Site)

Erigeron annuus (annual fleabane) | CABI Invasive Species Compendium (About This Site)

Erigeron annuus | Biota of North America Project (BONAP) (About This Site)

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