Arkansas Ironweed, Curlytop Ironweed, Great Ironweed

Vernonia arkansana

ver-NON-ee-uh  ar-kan-SAH-nuh

Synonyms of Vernonia arkansana (2) (Updated on 8-22-26 from Plants of the World Online): Cacalia arkansana (DC.) Kuntze (1891), Vernonia crinita Raf. (1838)

Vernonia arkansana DC. is the accepted scientific name for this species of Vernonia. It was named and described by Augustin Pyramus de Candolle in volume 7 of Prodromus Systematis Naturalis Regni Vegetabilis in 1838.

The genus, Vernonia Schreb., was named and described by Johann Christian Daniel von Schreber in the 8th edition of Genera Plantarum in 1791. 

As of 8-20-26 when this page was first written, Plants of the World Online lists 325 species in the Vernonia genus. It is a member of the plant family Asteraceae with 1,710 genera. Those numbers could change as updates are made on POWO.

The above distribution map for Vernonia arkansana is from the USDA Plants Database. The map on Plants of the World Online and Flora of North America are somewhat different. Areas in green are where the species is native. No map is perfect, but they do give a general idea.

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. I post all my observations on iNaturalist.

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

Until May 4 in 2025, I had been identifying wildflowers on the family farm, a friends farm and woods, along back roads and highways, etc. Then, on May 4 in 2025, a friend invited me to visit a private native prairie. It was incredible and I photographed 11 new to me species! We went back again on 4-19-26. I took friends on May 3, and there wasn’t much to see then. Then, on June 8 in 2026, he took me to the Lordi Marker Prairie then to Drover’s Prairie where I photographed 19 species, 10 new to me. On 6-22-26, I took my son, and we went to the Friendly Prairie for the first time, then on to the Lordi Marker and Drover’s Prairie. I photographed 22 species at the Friendly Prairie, 6 species at Lordi Marker Prairie, and 17 species at Drover’s Prairie. 11 more new to me. I went back to the Friendly and Drover’s Prairies on July 28 and photographed 12 species with 2 being new-to-me.

I first ran across this species while visiting the Friendly Prairie on June 22 in 2026. I found several plants with very odd looking buds and a few that had flowers. The flowers looked like ironweed, but the buds were definitely weird. I took several photos of these plants and 21 other species and went on to Drover’s Prairie. There I found several other plants of this species and photographed 17 other species. When I went back home, I saved the best photos and uploaded first of the the best of this species on the iNaturalist drag-and-drop feature (you have to be logged in) and their suggestion was Vernonia arkansana. I then cross-referenced their suggested species on the Missouri Plants website. It seemed iNaturalist was right again.

I had never encountered Vernonia arkansana before and was very happy to find it. The other Ironweeds on the farm and other areas were either what I figured was Vernonia baldwinii (Ironweed or Western Ironweed) and Vernonia missurica (Missouri Ironweed). No one on iNaturalist agreed because they are “controversial” species with similar characteristics. Vernonia arkansana is easily identified by its buds, and became Research Grade on iNaturalist within minutes after the observations were uploaded. 

I will come back later and write descriptions, but for now I just wanted to get the photos online. There are several links at the bottom of the page with information about the species and great descriptions.

 

 

 

 

 

 

I will continue to visit the three prairies and possibly others to take more photos and see what else I can find

I live on the family farm in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 250 species of wildflowers (most have pages listed on the right side of the page). 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 few horticulturalists I contact if I cannot figure them out. Wildflowers can be variable from location to location, so that can be 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 they have provided 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. 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 MISSOURI (GENUS/SPECIES)
FLORA OF NORTH AMERICA (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
iNATURALIST
MISSOURI PLANTS
MIDWEST WEEDS AND WILDFLOWERS
MISSOURI BOTANICAL GARDEN
MISSOURI DEPARTMENT OF CONSERVATION
WILDFLOWER SEARCH
OZARK EDGE WILDFLOWERS
FLORA FINDER
ILLINOIS WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
SEINet

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 one of the most reliable and up-to-date plant databases and they make updates regularly. 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. 🙂