| Author | (L.) Koehne | |
| Distribution | Essentially statewide, though sparse in the Mountains and perhaps absent from some counties there.
This is a wide-ranging species from coast to coast, ranging from NH and WA, south to all of FL, TX, and CA.
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| Abundance | Frequent to common in the Coastal Plain and most of the Piedmont; uncommon in the Mountains (lower elevations). | |
| Habitat | This is one of the more frequently seen herbs on muddy drawdown zones of lakes, ponds, and creeksides. It also grows in ditches, marshes, and other damp (usually muddy) ground. | |
| Phenology | Blooms from June to October, and fruits shortly after flowering. | |
| Identification | This is a familiar lake and pond margin species, growing in colonies to about 1 foot tall on average, usually moderately branched. It is a glabrous species, with numerous pairs of opposite leaves, usually growing horizontally. Each leaf is narrowly lanceolate or oblanceolate, to narrowly elliptical, entire, about 1.5 inches long, with a tapering base and a rounded tip. The small flowers grow singly in the leaf axils. The calyx is rounded, almost globose, and the 4 petals are white but tiny. The two Ammannia species are somewhat similar, with numerous opposite, ladder-like leaf arrangements, but they have some or all leaves with auriculate bases, and larger flowers that are typically in small clusters in the axils (and not single as in Rotala). | |
| Taxonomic Comments | None
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| Other Common Name(s) | Toothcup. This might be a better common name than Lowland Rotala, but the issue is that Ammannia coccinea typically is named as Scarlet Toothcup. Thus, Rotala would need a modifier name (xxxxxx Toothcup), and one does not seem available. | |
| State Rank | S5 | |
| Global Rank | G5 | |
| State Status | | |
| US Status | | |
| USACE-agcp | OBL link |
| USACE-emp | OBL link |
