| Isoetaceae | |
Isoetes engelmannii var. caroliniana
| A.A. Eaton | Fern Bull. 8: 60 | 1900 |
| Isoetaceae | |
Isoetes engelmannii var. engelmannii
| | | |
| Isoetaceae | |
Isoetes engelmannii var. fontana
| A.A. Eaton | Fern Bull. 13: 52 | 1905 |
| Isoetaceae | |
Isoetes engelmannii var. georgiana
| Engelm. | Trans. Acad. Sci. St. Louis 4: 384 | 1882 |
| Isoetaceae | |
Isoetes engelmannii var. gracilis
| Engelm. | Manual (ed. 5) 677 | 1867 |
| Isoetaceae | |
Isoetes engelmannii var. valida
| Engelm. | Manual (ed. 5) 677 | 1867 |