Acmella repens (Walter) L.C. Richard in Persoon. Creeping Spotflower. Phen: Jul-Dec. Hab: Floating vegetation mats, blackwater levee and swamp forests, roadsides, streambanks, other moist, open, habitats. Dist: Se. NC south to s. FL, west to e. TX, north in the Mississippi Embayment to w. TN and s. MO.

Origin/Endemic status: Endemic

Taxonomy Comments: Jansen (1985) treats this as var. repens of A. oppositifolia, the typic var. oppositifolia widely distributed from c. Mexico south through Central America into n. South America, stating that var. repens "can be easily separated from var. oppositifolia by its lanceolate, acuminate phyllaries and short double hairs on the achene margins". Jansen also states that "four factors have caused extreme difficulties in delimiting taxa at the specific and infraspecific level within this group: very close morphological similarity; polyploidy; hybridization, especially between different ploidy levels; and asexual reproduction". In his more statistical taxonomic analyses, his var. repens (tetraploid, and the only taxon out of 39 native to North America) separates rather well from A. oppositifolia (diploid, tetraploid, and hexaploid). Given the morphological distinctiveness and substantial allopatry of the two taxa, we prefer not to associate this taxon as a variety of the complex A. oppositifolia.

Synonymy ⓘ: = Ar, FNA21, Il, K3, K4, Ok, Tn; = Acmella oppositifolia (Lam.) R.K.Jansen var. repens (Walter) R.K.Jansen – Fl7, K1, NcTx, WH3, Jansen (1985); = Spilanthes americana (Mutis ex L.f.) Hieron. var. repens (Walter) A.H.Moore – F, RAB, Tx; < Spilanthes americana (Mutis ex L.f.) Hieron. – C, G, GW2, S, SE1

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACW
• Eastern Mountains and Piedmont: FACW
• Great Plains: FACW
• Midwest: FACW

Heliophily ⓘ: 7