| Name | Children | Media (from resource) | Traits |
|---|---|---|---|
| Acanthoceras | 0 | 2 | 0 |
| Acanthocerotaceae | 1 | 0 | 0 |
| Acanthocystidae | 8 | 18 | 0 |
| Acanthocystis pectinata Penard 1889 | 0 | 1 | 0 |
| Acanthocystis penardi Wailes 1925 | 0 | 2 | 0 |
| Acanthocystis turfacea | 0 | 3 | 0 |
| Achnanthaceae | 2 | 12 | 0 |
| Achnanthales | 1 | 0 | 0 |
| Achnanthes Bory de Saint-Vincent 1822 | 0 | 11 | 0 |
| Achnanthes longipes C. Agardh 1824 | 0 | 5 | 0 |
| Achromatium oxaliferum | 0 | 2 | 0 |
| Acineta tuberosa | 0 | 7 | 0 |
| Acinetidae | 2 | 19 | 0 |
| Acrochaetiaceae | 1 | 18 | 0 |
| Acrochaetiales | 1 | 18 | 0 |
