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 (26) (Updated on 10-17-21 from Plants of the World Online): 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. ciliatifolia A.H.Moore, Spilanthes americana f. lanitecta A.H.Moore, Spilanthes americana f. longiinternodiata 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 still lists 32 accepted species in the Acemella genus (as of 10-17-21 when this page was last updated). The genus 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 this family fluctuates up or down quite often.

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 the United States and Canada is the same. The species may be more widespread than the maps show.

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.

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
FLORA OF NORTH AMERICA (GENUS/SPECIES)
WORLD FLORA ONLINE (GENUS/SPECIES)

WIKIPEDIA (GENUS/SPECIES)
MISSOURI PLANTS
DAVE’S GARDEN
iNATURALIST
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. 🙂

 

2 comments on “Acmella repens-Oppositeleaf Spotflower

  1. shoreacres says:

    I did find this page useful! I’ve been trying to identify this flower since 2019. I found an isolated patch of it at a nearby wildlife refuge; it’s the only time I’ve seen it. I knew it belonged in the Asteraceae, but it isn’t in any of my books, and not on any photo ID sites I consult.

    So, you might wonder: how did I get here? It’s a funny story. I have my first iphone, which I purchased after seeing how the Picture This app worked on a friend’s phone. I took a photo of the photo of this flower I had on my computer, and lo and behold, it gave me a name. When I went to a search engine with that name — well, here I am!

    I’ve subscribed to your blog now, and look forward to browsing the archives. I did wonder if the Wagler you mention is the same as the Wagler I’ve bought black walnuts from. I have an aunt who lives in Blue Springs, and every time I go up there, I take her black walnuts in some form. Also, I know why your screen name’s vaguely familiar: I follow Laurie Graves, Tony Tomeo, Littlesundog, and others who’ve commented here.

    For all its downside, this internet’s a marvelous thing!

    Liked by 1 person

    • Hello Shoreacres! Great to hear from you and I am thrilled you found this page useful. It isn’t an easy plant to find. I was sure I saw it at the corner of the barn back in 2013 or 2014 but I don’t see any photos of it from that period. It could have been a different species I saw earlier. You know how wildflowers are. They seem to travel a bit and that corner of the barn is weird. I haven’t seen this plant in that spot since 2019, but it could be elsewhere and I haven’t noticed. Since it has yellow flowers, from a distance I may have thought it was something else and didn’t check. I will have to pay more attention…

      So, did you come to Windsor to buy walnuts? If you bought walnuts from a Wagler in Windsor, then I probably know who they are. Ruth Wagler’s son owns Wagler’s Greenhouse and another son has a farm and grows melons and tomatoes. The Amish before you get to the greenhouse buys walnuts.

      I haven’t posted for a while because I have been updating pages and adding new ones. I am sure Laurie, Lori, Tony, and others have been wondering if I am still alive. 🙂 Answering your comment confirms I am still alive.. I have been having camera issues and need to buy a new one. It has been having lens issues and I finally screwed it up trying to get it to work after I took photos on Monday. Time for a new one… I do not have a cell phone and don’t want one… I do love my two iMacs and the internet.

      Thanks again for the comment. If you are down this way (or up) stop in for a visit. Take care!

      Liked by 1 person

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