Erigeron annuus (Annual Fleabane)

Erigeron annuus (Annual Fleabane) on 10-6-18, #517-2.

Annual Fleabane, Eastern Daisy Fleabane

Erigeron annuus

(Erigeron annuus subsp. annuus)

er-IJ-er-on  AN-yoo-us

Synonyms of Erigeron annuus (5) (Updated on 1-15-21 from Plants of the World Online): Aster annuus L., Erigeron annuus var. typicus Cronquist, Phalacroloma acutifolium Cass., Phalacroloma annuum (L.) Dumort., Stenactis annua (L.) Cass. ex Less.
Synonyms of Erigeron annuus subsp. annuus (15) (Updated on 1-15-21 from POWO): Aster stenactis E.H.L.Krause, Cineraria corymbosa Moench, Diplopappus annuus Bluff & Fingerh., Diplopappus dubius Cass., Doronicum bellidiflorum Schrank, Erigeron annuus f. discoideus Vict. & J.Rousseau, Erigeron annuus var. discoideus (Vict. & J.Rousseau) Cronquist, Erigeron bellidioides Spenn., Erigeron diversifolius Rich. ex Rchb., Erigeron heterophyllus Muhl. ex Willd., Erigeron strigosus Bigelow, Pulicaria annua Gaertn., Pulicaria bellidiflora Wallr., Stenactis annua Cass., Stenactis dubia Cass.

 Erigeron annuus (L.) Desf. is the accepted scientific name for the Annual Fleabane. It was named and described as such by René Louiche Desfontaines in Tableau de l’École de Botanique du Muséum d’Histoire Naturelle in 1804. It was first named Aster annuus by Carl von Linnaeus in the second edition of Species Plantarum in 1753.

Most databases and websites say Erigeron annuus (L.) Pers., as named and described by Christiaan Hendrik Persoon in Synopsis Plantarum in 1807. However, the International Plant Names Index says this scientific name is an isonym since it was published after the original.

Accepted Infraspecific Names (2): *Erigeron annuus subsp. annuus (autonym), Erigeron annuus subsp. lilacinus Sennikov & Kurtto. *When infraspecific taxon are named, an autonym (“type-specimen”) is automatically generated whose description is closest to the (original) species. All have their own list of synonyms… 

The genus, Erigeron L., was named and described by Carl von Linnaeus in the second edition of Species Plantarum in 1753. 

As of 1-15-21 when this page was last updated, Plants of the World Online lists 456 species in the Erigeron genus. It is a member of the plant family Asteraceae with 1,677 genera. Those numbers could change as updates are made on POWO. The number of genera in the family fluctuates quite often.

Distribution map of Erigeron annuus from Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/. Retrieved on November 1, 2021.

The above distribution map for Erigeron annuus is from Plants of the World Online. Areas in green are where the species is native and purple where it has been introduced. This map shows where the species has been introduced in other countries. Erigeron annuus subsp. lilacinus is native to Baltic States, Finland, Sweden, Taiwan, and Vietnam.

Distribution map for Erigeron annuus from the USDA Plants Database. Published on the internet at https://plants.sc.egov.usda.gov/home. Retrieved on November 1, 2021.

The above distribution map for Erigeron annuus is from the USDA Plants Database for North America above Mexico. It shows the species is native to more states than POWO.

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as members post new observations.

BONAP (The Biota of North America Program) maps are also very good. Clicking HERE will take you to the page of maps for all the Erigeron species in the United States. 

No maps are perfect and species in this genus are difficult…

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH A BETTER POSITIVE ID.

Erigeron annuus (Annual Fleabane) on 10-22-21, #849-10.

There are quite a few colonies of Erigeron annuus (Annual Fleabane) growing on my farm, especially in the south hayfield. A very similar species, Erigeron strigosus (Daisy Fleabane), has narrower leaves otherwise they can be difficult to tell apart. One may also get them confused with species of Symphyotrichum at a glance, but Erigeron species have larger central discs (cones). There are more differences between the two genera but they do have features in common.

Erigeron annuus can grow as an annual or biennial. This species isn’t picky about soil type and can grow in full sun to part shade. They can be found in pastures, prairies, fence rows, along roadsides, ditches, fields, and so on. Plants grow from 1-5 feet or more in height and are said to be able to compete with invasive species quite well. The species is native to North and Central America and has also been introduced to other countries. In North America, their range is from the central part eastward then scattered from California up into Canada. No map is perfect and their range in some states may be very limited while quite widespread in others. The subspecies, Erigeron annuus subsp. lilacinus is only found in the Baltic States, Finland, Sweden, Taiwan, and Vietnam (according to the map on POWO).

Erigeron annuus (Annual Fleabane) on 10-12-21, 843-19.

Stems are normally ridged and can be fairly smooth to fairly hairy.

Erigeron annuus (Annual Fleabane) on 10-22-21, #849-8.

The leaves grow in an alternate pattern along the stems. The lower leaves have fairly long, winged petioles (leaf stems), are 3-5” long, lanceolate, ovate, to oblanceolate in shape. Upper leaves are smaller without petioles, and usually more lanceolate. Lower leaves are coarsely serrated while the upper leaves may only have a few teeth toward the outer tips.

There are two similar species of Erigeron found in Missouri that have similar flowers. Erigeron philadelphicus (Marsh or Philadelphia Fleabane) has clasping leaves. Erigeron strigosus (Daisy Fleabane) has more slender leaves. They both have other distinguishing features…

Erigeron annuus (Annual Fleabane) on 10-6-18, #517-3.

The above photo shows flowers on top of numerous long peduncles (flower stems) and numerous bracts surrounding the ray florets (petals).

Erigeron annuus (Annual Fleabane) on 10-12-21, 843-16.

Erigeron annuus stems terminate with clusters of small white to pinkish flowers with fairly long flower stems (peduncles). The flowers have 50-120 white ray florets (petals) and A LOT of yellow disc florets in the center. The yellow corollas of the disc florets are 5-lobed. Both the ray and disc florets can be self-fertile.

Erigeron annuus (Annual Fleabane) on 10-12-21, 843-17.

Bracts (involucral bracts) below the heads are green, lanceolate in shape, for kind of a vase for the flowers. Single or double row.

Erigeron annuus (Annual Fleabane) without petals on 10-6-18, #517-4.

I found this cluster of Erigeron annuus in the south hayfield that had lost their ray florets…

Erigeron annuus (Annual Fleabane) on 6-19-19, #592-16.

The flowers are around 1/2-3/4″ wide. The flowering period is April through November as long as weather permits…

Erigeron annuus (Annual Fleabane) on 10-12-21, 843-20.

The above photo is of the buds of the Erigeron annuus

Erigeron annuus (Annual Fleabane) on 10-22-21, #849-9.

The above photo is a side view showing the upper leaves with smooth margins, the flowers on fairly long peduncles (flower stems) that are swollen below the bracts.

Erigeron annuus (Annual Fleabane) on the right and Symphyotrichum pilosum (Hairy While Oldfield Aster) on the left on 10-22-21, #849-5.

The above photo is a comparison of the flowers of Erigeron annuus (Annual Fleabane) on the right and Symphyotrichum pilosum (Hairy White Oldfield Aster) on the left.

I had a few issues identifying several species of wildflowers on my farm that looked similar. For a while, I was getting the Erigeron annuus confused with a few species in the Symphyotrichum genus but I finally got that figured out. I took photos for several years but kind of ignored them until 2021 when I figured it was time to give them a proper ID…

I have enjoyed photographing and learning about the many wildflowers growing on the farm in Windsor, Missouri in Pettis County (Henry County is across the street) and other areas. The city limits is also across the street and the north and south side of the farm. I have grown over 500 different plants and most have pages listed on the right side of the blog. I am not an expert, botanist, or horticulturalist. I just like growing, photographing and writing about my experience. I rely on several websites for ID and a horticulturalist I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX 
(GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
FLORA OF NORTH AMERICA (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
DAVE’S GARDEN
MISSOURI PLANTS
MSU-MIDWEST WEEDS AND WILDFLOWERS
iNATURALIST
WILDFLOWER SEARCH
USDA PLANTS DATABASE
ILLINOIS WILDFLOWERS
MINNESOTA WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
PFAF (PLANTS FOR A FUTURE)
GO BOTANY
FLORA FINDER

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is the most reliable and up-to-date plant database and they make updates on a regular basis. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂

 

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