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 (23): 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 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 named and described as such by Christiaan Hendrik Persoon in Synopsis Plantarum in 1807. In the description, he acknowledges Louis Claude Marie Richard’s previous description that wasn’t validly published (that’s why it says “ex”). It is sometimes cited as Acmella repens (Walter) Rich. or Rich. ex Pers. It was first named and described as Anthemis repens by Thomas Walter in Flora Caroliniana in 1788.

Plants of the World Online lists 31 accepted species in the Acemella genus as of 1-8-20 when I am writing this page. That number could change.  

 

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.

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.

Here on this farm in Pettis County in Missouri (Henry County is across the street), 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, took photos, and misidentified it. Strangely, it seems they looked different than in 2019 but they were probably this same plant. 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. Takes a lot more than just flowers sometimes to make a positive ID.

There is not a whole lot online about this plant and most of my information about this plant comes from the Missouri Plants website. I have noticed a few websites that show a plant by this name with different leaves.

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 unnoticed.

Botanical terminology is sometimes difficult to understand so I will do my best to describe identifying parts the way I understand. 🙂 The “bold” print is copied from Missouriplants.com. by permission from the site administrator. 

 

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

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

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. 

FLOWERS: “Radiate (spreading with a common center), with conical receptacle elongating with maturity. Involucre 4-6 mm long, the bracts in 2 similar series. Involucral bracts 6-16, ascending, lanceolate, sharply pointed, green, with slightly irregular margins, the outer surface glabrous or sparsely hairy, with usually 3 fine nerves. Chaffy bracts subtending the ray and disc florets, these folded longitudinally and more or less wrapped around the florets.”

FLORETS: “Ray florets 5-15, pistillate, the corolla 3-9 mm long, relatively broad, yellow to orangish-yellow, sparsely hairy toward the base. Disc florets numerous, perfect, the corolla 1.5-3.0 mm long, yellow, glabrous. Pappus of the ray and disc florets absent or the disc florets rarely with 1 or 2 short, slender awns.”

Hmmm… OK, I am not a botanist, horticulturalist or a genius. In common language, the flowers of the Acmella repens are pretty unmistakable when you take into consideration the leaves as well. They are saying here that there can be from 5 to 15 petals (ray florets) surrounding the “cone” in the center which composed of the “disc florets”. If you notice, the “petals” appear to “3 petals in one”. That’s the best way I can describe it. The flower in the above photo seems to have a few missing but that is the best I can do. Hopefully, in 2020 I can find more or these plants and take better photos.

The bracts are pictured in the last photo because the photos of them didn’t come out so good on September 30.

 

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

LEAVES: “Opposite, or the uppermost few alternate, petiolate. Leaf blades 1-8 cm long, narrowly lanceolate to broadly ovate, bluntly or more commonly sharply pointed, the margins finely to coarsely and bluntly to sharply toothed, the surfaces glabrous or sparsely pubescent along the veins with soft, curved hairs.”

This plant has several types of leaves on the same plant. The larger leaves, as in the above photo, are set opposite each other, broad and lance-shaped, with toothed margins. Petiolate means they are connected to the stem with a petiole (the stem between the lower part of the leaf and stem). Pubescent means very short, soft downy hairs… Which you can barely notice on these leaves without good eyesight or magnification.

 

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

STEM: 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.

The Acmella repens I found is a sprawling plant whos stems were laying on the ground.

 

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

Here isa smaller leaf which 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.

Here is a good example of the bracts on a younger flower. The “involucral bracts’ surround the flowers at the base. The “chaffy bracts”, which obviously you can’t see in this photo, “subtend” the “florets”.

This is a very interesting plant, perhaps because I only found this very small group. There isn’t very much online about this plant at the moment and I was delighted to find it in my own back yard. If it returns in 2020, I will take more photos. Maybe I can find it growing in other areas as well before October in 2020. I will keep my eyes open for them.

Some of the links may take you to a plant with a different name. That is either because they use a different name or their site isn’t updated.

I have enjoyed photographing and learning about the many wildflowers growing on the farm and other areas. 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. 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.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
*MISSOURI PLANTS*
*iNATURALIST.ORG*
*WILDFLOWERSEARCH.ORG*
USDA PLANTS DATABASE
THE NATIONAL GARDENING ASSOCIATION
LADY BIRD JOHNSON WILDFLOWER CENTER