| Acanthaceae | Acanthus family |
| Acoraceae | Sweetflag family |
| Adoxaceae | Moschatel family |
| Agavaceae | Agave family |
| Alismataceae | Water-plantain family |
| Alliaceae | Onion family |
| Altingiaceae | Sweet-gum family |
| Amaranthaceae | Amaranth family |
| Amaryllidaceae | Amaryllis family |
| Amblystegiaceae | Amblystegium moss family |
| Anacardiaceae | Cashew family |
| Annonaceae | Custard-apple family |
| Anomodontaceae | |
| Apiaceae | Carrot family |
| Apocynaceae | Dogbane family |
| Aquifoliaceae | Holly family |
| Araceae | Arum family |
| Araliaceae | Ginseng family |
| Aristolochiaceae | Birthwort family |
| Asparagaceae | Asparagus family |
| Aspleniaceae | Spleenwort family |
| Asteraceae | Aster family |
| Azollaceae | Mosquito Fern family |