| Author | Sprengel | |
| Distribution | Primarily in the Coastal Plain; also Anson and Randolph counties in the eastern Piedmont. First collected in 1935 in Washington County.
Native of South America; in N.A. VA to FL, TX, and OK; also CA, AZ, UT. | |
| Abundance | Infrequent to locally fairly common in the Coastal Plain, but rare in the Piedmont. | |
| Habitat | Roadsides, railroad margins, fallow fields, open woods. | |
| Phenology | Flowering and fruiting late March-July. | |
| Identification | This vervain is a fairly familiar low-growing one in the Coastal Plain. It can be erect or reclining, with stems up to 2 feet long. The plants grow from elongate, horizontal, underground stolons -- a notable feature that separates it from our other vervains. The leaves are lanceolate to narrowly elliptical, serrated, and clasping at the bases. The flowers are bright rosy or purple on spikes that are 1-2.5 inches long, with each inflorescences being rounded/ball-like. | |
| Taxonomic Comments | | |
| Other Common Name(s) | Tuber Vervain, Stiff Vervain, and many other names | |
| State Rank | SE | |
| Global Rank | GNR | |
| State Status | | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
