Acmella repens-Oppositeleaf Spotflower

Acmella repens (Oppositeleaf Spotflower) on 9-30-19.

Oppositeleaf Spotflower

Acmella repens

ak-MEL-uh  REE-penz

Synonyms of Acmella repens from Plants of the World Online (24) (Updated on 3-1-21): Acmella nuttaliana Raf., Acmella occidentalis Nutt., Acmella oppositifolia var. repens (Walter) R.K.Jansen, Anthemis repens Walter, Anthemis trinervia Sessé & Moc., Ceratocephalus beccabunga Kuntze, Ceratocephalus repens (Walter) Kuntze, Ceratocephalus subhirsutus Kuntze, Spilanthes americana f. lanitecta A.H.Moore, Spilanthes americana var. parvula (B.L.Rob.) A.H.Moore, Spilanthes americana var. repens (Walter) A.H.Moore, Spilanthes beccabunga DC., Spilanthes beccabunga var. parvula B.L.Rob., Spilanthes ciliata var. diffusa A.H.Moore, Spilanthes cocuyensis Cuatrec., Spilanthes diffusa Poepp. & Endl., Spilanthes disciformis var. phaneractis Greenm., Spilanthes lateraliflora Klatt, Spilanthes lehmanniana Klatt, Spilanthes nuttallii Torr. & A.Gray, Spilanthes orizabaensis Sch.Bip. ex Klatt, Spilanthes phaneractis (Greenm.) A.H.Moore, Spilanthes repens (Walter) Michx., Spilanthes subhirsuta DC.

Acmella repens (Walter) Rich. ex Pers. is the correct and accepted name for this species of Acmella. The genus and species were described as such by Christiaan Hendrik Persoon in Synopsis Plantarum in 1807. He gave credit to Louis Claude Marie Richard for naming the genus and species. It is sometimes cited as Acmella repens (Walter) Rich. or Rich. ex Pers. It was first named and described as Anthemis repens by Walter Thomas in Flora Caroliniana in 1788.

Plants of the World Online lists 32 accepted species in the Acemella genus (as of 3-1-21 when I last updated this page. The genus is a member of the plant family Asteraceae with 1,679 genera. Those numbers could change as updates are made. 

Distribution map for Acmella repens used by permission from Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/. Retrieved January 8, 2020.

The above distribution map for Acmella repens is from Plants of the World Online. Areas in green are where the plant is native and purple where it has been introduced. The map on the USDA Plants Database for North America is the same. The species may be more widespread than the maps show.

Acmella repens is found growing in the United States in Missouri and Texas eastward in the south part of the country toward the east coast, Mexico south through parts of South America, Costa Rica, and Cuba.

 THERE ARE A FEW LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH PLANT IDENTIFICATION.

Acmella repens (Oppositeleaf Spotflower) on 9-30-19, #636-2.

I have only noticed this plant growing in a small spot along the northwest corner of the barn. I think I first noticed it growing here a few years ago. I took photos, and maybe misidentified it because I can’t find the older photos. I have gotten more into wildflower ID so I make sure I take ample photos of the entire plant whereas a few years ago I probably just took photos of the flowers. It takes a lot more than just flowers sometimes to make a positive ID.

This plant only seems to show up in the yard by the barn late in the season. I either don’t notice it since I mow this area weekly or it just emerges. They may grow in other areas on the farm but this is the only spot I have noticed it so far. They seem to be a low-growing sprawling plant, so they may grow unnoticed among taller weeds (I mean wildflowers) and grass.

Acmella reptans is a herbaceous perennial that grows in swampy areas, low wet woods, borders of pods, and areas beginning to dry out. 

Acmella repens (Oppositeleaf Spotflower) on 9-30-19, #636-3.

 This plant has several types of leaves on the same plant. Leaves are mainly opposite while upper leaves may be alternate. Leaves are petiolate, narrowly lanceolate to broadly ovate, bluntly or sharply pointed. Margins of leaves are finely to coarsely and bluntly to sharply toothed. Leaf surfaces are smooth (glabrous) or covered with short, soft hairs (pubescent) along the veins.

Acmella repens (Oppositeleaf Spotflower) on 9-30-19, #636-4.

The spreading (or sprawling) stems are up to 36” long (3 m), finely ridged or grooved, with pubescent hairs. Stems often root at their lower nodes. Stems can be green, reddish, or a combination of the two.

Acmella repens (Oppositeleaf Spotflower) on 9-30-19, #636-5.

The undersides of the leaves show prominent veins and midribs. Some are kind of chalky looking which is from fine hairs.

Acmella repens (Oppositeleaf Spotflower) on 10-1-19, #637-1.

They have a fibrous root system, sometimes rhizomatous. The spreading (or sprawling) stems are up to 36” long (3 m), finely ridged or grooved, with pubescent hairs. Stems often root at their lower nodes.

Acmella repens (Oppositeleaf Spotflower) on 10-1-19, #637-2.

Here is a smaller leaf that is more narrowly lance-shaped and not so deeply lobed.

Acmella repens (Oppositeleaf Spotflower) on 10-1-19, #637-3.

 

Acmella repens (Oppositeleaf Spotflower) on 10-1-19, #637-4.

The single flower heads emerge from the top of the plant’s branches and central stem. Flower heads consist of 5-15 yellowish ray florets (petals) and a cluster of disc flowers in the center. A series of 6-16 chaffy bracts surround the flower. The cone of disc flowers elongates as the plant matures. For a better technical description, see the link to Missouri Plants below.

I didn’t see this plant in 2020 and it doesn’t seem to appear every year. I will keep an eye out for it next to the barn and other areas in 2021. This species flowers from July through October…

There isn’t that much online about the Acmella repens and some of the websites showed plants with different leaves…

I have enjoyed photographing and learning about the many wildflowers growing on the farm and other areas. My farm is 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 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 few horticulturalists 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
WORLD FLORA ONLINE (GENUS/SPECIES)

WIKIPEDIA (GENUS/SPECIES)
MISSOURI PLANTS
DAVE’S GARDEN
iNATURALIST.ORG
WILDFLOWERSEARCH.ORG
USDA PLANTS DATABASE
THE NATIONAL GARDENING ASSOCIATION
LADY BIRD JOHNSON WILDFLOWER CENTER

NOTE: The figures may not match on these websites. It depends on when and how they make updates and when their sources make updates (and if they update their sources or even read what they say). Some sites 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. 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 but I do get behind. We are all a work in progress. 🙂

 

Please leave a comment. I would like to hear from you.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.