| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|---|---|---|---|---|
| Rubiaceae | Hexasepalum radulum | Chrome ore piles and ballast, a waif. | Native of South America. |  (c) JG - CC-BY | |
| Rubiaceae | Hexasepalum teres | Poorjoe | Dunes, sandy roadsides, glades, hardpans, other dry habitats. | Massachusetts, New York and Wisconsin, south to Florida, Texas, and California, south through Mexico and Central America. |  (c) Keim, Mary - CC-BY-NC-SA, permission granted to NCBG |