This is a pretty, but ubiquitous plant that will appear on its own without any official encouragement. It can be distinguished from asters with similar flowers by its earlier blooming season and more numerous ray florets. Annual Fleabane differs from Erigeron strigosus (Daisy Fleabane) by its more numerous and broader leaves, and the long spreading white hairs that occur along the entire length of the stems. Daisy Fleabane, on the other hand, has more slender leaves and short appressed hairs that occur along the middle and upper portions of the stems.

This is a native annual or biennial plant that is up to 3½' tall, branching occasionally in the upper half to form flowering stems. The central stem has spreading white hairs throughout its length. The leaves toward the base are 3-5" long with sizable petioles, and they are lanceolate, ovate, or oblanceolate in shape. The leaves along the upper stems are smaller in size, without petioles, and usually lanceolate. These alternate leaves are rather common along the stems, even toward the top of the plant. The lower leaves are often coarsely serrated or dentate, while the upper leaves may have a few coarse teeth toward their outer tips. Small clusters of daisy-like composite flowers occur toward the apex of the plant, each about ½–¾" across. The central disk florets are numerous, very small, and yellow; they are surrounded by 50-120 white ray florets. Both kinds of florets can be self-fertile. The flower buds often have conspicuous white hairs. The blooming period begins in early summer and continues intermittently until the fall, usually with a lull during the hot weather of late summer. A mild fragrance is sometimes detectable. The root system is fibrous and spreading. The achenes have tufts of small hairs (which they sometimes lose); they are distributed by the wind.

Erigeron annuus (L.) Pers.:
Canada (North America)
Costa Rica (Mesoamerica)
Mexico (Mesoamerica)
Nicaragua (Mesoamerica)
Panama (Mesoamerica)
United States (North America)

Erigeron annuus var. discoideus (Vict. & J. Rousseau) Cronquist:
Canada (North America)
United States (North America)

Erigeron annuus fo. discoideus Vict. & J. Rousseau:
Canada (North America)

Aster annuus L.:
Canada (North America)

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Annual Fleabane is very common, and has been reported in every county in Illinois (see Distribution Map). Typical habitats include disturbed areas of moist to slightly dry prairies, pastures and abandoned fields, areas along roadsides and railroads, disturbed open woods, and various kinds of waste areas. This is a native pioneer species that competes directly with many Eurasian weeds.

Erigeron annuus is apparently native to eastern North America (United States and southern Canada) and is introduced elsewhere; it probably occurs in North Dakota and Alberta; apparently it has not been documented there. Apparent intermediates between E. annuus and E. strigosus are encountered.

Annuals, (10–)60–150 cm; fibrous-rooted or taprooted. Stems erect, sparsely piloso-hispid (hairs spreading), sometimes strigose distally, eglandular. Leaves basal (usually withering by flowering) and cauline; basal blades mostly lanceolate to oblanceolate or ovate, 15–80 × 3–20 mm, margins coarsely serrate to nearly entire, faces sparsely strigoso-hirsute, eglandular; cauline lanceolate to oblong, little reduced proximal to midstem. Heads ca. 5–50+ in loosely paniculiform or corymbiform arrays. Involucres 3–5 × 6–12 mm. Phyllaries in 2–3(–4) series, sparsely villous or hirsuto-villous, minutely glandular. Ray florets 80–125; corollas white, 4–10 mm, laminae tardily coiling. Disc corollas 2–2.8 mm. Cypselae 0.8–1 mm, 2-nerved, faces sparsely strigose; pappi: outer minute crowns of setae or narrow scales, inner 0 (rays) or of 8–11 bristles (disc). 2n = 27.

Aster annuus Linnaeus, Sp. Pl. 2: 875. 1753; Erigeron annuus var. discoideus (Victorin & J. Rousseau) Cronquist

Annual Fleabane is very common, and has been reported in every county in Illinois (see Distribution Map). Typical habitats include disturbed areas of moist to slightly dry prairies, pastures and abandoned fields, areas along roadsides and railroads, disturbed open woods, and various kinds of waste areas. This is a native pioneer species that competes directly with many Eurasian weeds.

Erigeron annuus (Annual Fleabane)
(Short-tongued bees collect pollen or suck nectar; long-tongued bees suck nectar, with exceptions noted below; flies and beetles feed on pollen or suck nectar; other insects suck nectar; most observations are from Graenicher, although two observations are from Robertson, as noted below)

Bees (long-tongued)
Apidae (Bombini): Psithyrus citrinus sn; Anthophoridae (Ceratinini): Ceratina dupla dupla sn cp; Anthophoridae (Nomadini): Nomada articulata sn; Megachilidae (Osmiini): Hoplitis pilosifrons sn cp, Osmia distincta sn; Megachilidae (Trypetini): Heriades leavitti sn (Rb)

Bees (short-tongued)
Halictidae (Halictinae): Agapostemon sericea sn cp, Augochlorella striata sn cp, Halictus rubicunda sn, Halictus spp. (Lasioglossum spp.) sn, Lasioglossum albipennis sn cp, Lasioglossum connexus sn, Lasioglossum coriaceus sn, Lasioglossum cressonii sn cp, Lasioglossum imitatus sn, Lasioglossum tegularis sn cp, Lasioglossum versatus sn cp, Lasioglossum zephyrus sn; Halictidae (Sphecodini): Sphecodes davisii sn; Colletidae (Hylaeinae): Hylaeus affinis sn, Hylaeus mesillae sn cp, Hylaeus modestus modestus sn cp; Andrenidae (Andreninae): Andrena robertsonii sn; Melittidae: Macropis nuda sn

Wasps
Sphecidae (Crabroninae): Ectemnius dives, Lestica producticollis, Oxybelus uniglumis; Vespidae (Eumeninae): Euodynerus foraminatus, Parancistrocerus pensylvanicus

Flies
Syrphidae: Eristalis transversus, Eupeodes americanus, Sphaerophoria contiqua, Syritta pipiens, Toxomerus geminatus, Toxomerus marginatus; Conopidae: Thecophora abbreviata; Stratiomyidae: Nemotelus nigrinus, Odontomyia virgo; Chloropidae: Meromyza americana; Anthomyiidae: Delia platura; Calliphoridae: Lucilia illustris, Lucilia sericata; Sarcophagidae: Helicobia rapax, Sarcophaga sp., Sphixapata trilineata; Tachinidae: Copecrypta ruficauda, Cylindromyia dosiades, Epigrimyia polita, Gymnoclytia immaculata, Gymnosoma fuliginosum, Periscepsia laevigata sn (Rb), Phasia aeneoventris, Phyllomya cremides, Strongygaster triangulifera; Tephritidae: Euaresta bella; Agromyzidae: Melanagromyza aeneoventris

Skippers
Hesperiidae: Poanes hobomok

Beetles
Curculionidae: Rhynchaenus pallicornis; Mordellidae: Hoshihananomia octopunctata, Mordellistena comata; Scarabaeidae (Cetonniae): Trichiotinus piger

Plant Bugs
Lygaeidae: Lygaeus turcicus; Miridae: Leptoterna dolobrata, Lygus lineolaris, Plagiognathus politus, Poecilocapsus lineatus; Pentatomidae: Euschistus variolaria; Thyreocoridae: Corimelaena pulicarius

Various long-tongued and short-tongued bees visit the flowers, including Little Carpenter bees, Cuckoo bees, Halictine bees, and Masked bees. They collect pollen or suck nectar. Flies are common visitors, including Syrphid flies, bee flies, Tachinid flies, flesh flies, Anthomyiid flies, and Muscid flies. To a lesser extent, wasps, small butterflies, and other insects visit the flowers – all of these insects seek nectar primarily, except for a few pollen-feeding beetles. The caterpillars of Schinia lynx (Lynx Flower Moth) feed on the flowers and seed capsules of Annual Fleabane and other fleabanes, while Lygus lineolaris (Tarnished Plant Bug) sucks plant juices. Some mammalian herbivores have been observed eating the foliage, flowers, and stems, including sheep, groundhogs, and rabbits.

The following is a representative barcode sequence, the centroid of all available sequences for this species. 

 
There are 11 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
 

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 13
Species: 14
Species With Barcodes: 1

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

The preference is full or partial sun, and moist to mesic conditions. This plant isn't fussy about soil characteristics, and tolerates clay or gravel to a greater extent than many others. It's easy to grow, but can spread aggressively by re-seeding itself in disturbed areas. Sometimes the lower leaves will turn yellow and wither away during hot dry weather. The size of Annual Fleabane can vary considerably depending upon soil fertility, moisture amounts, and competition from neighboring plants.