| Macaranga capensis | Mallota capensis, Mappa capensis |
| Mackaya bella | Asystasia bella |
| Mackfadyena unguis-cati | Doxanthus unguis-cati, Bignonia tweediana |
| Maclura pomifera | Maclura aurantiaca, Toxylon pomifera |
| Macrozamia miquelii | Encephalartos miquelii, Macrozamia mackenzii |
| Maerua edulis | Courbonia edulis |
| Magnolia coco | Magnolia pumila, Michelia coco, Michelia pumila |
| Malpighia glabra | Malpighia punicifolia, Malpighia uniflora |
| Malvaviscus arboreus var. drummondii | Malvaviscus drummondii |
| Mandevilla suaveolens | Amblyanthera suaveolens, Echites suaveolens, Mandevilla laxa |
| Manfreda virginica | Agave virginica, Polianthes virginica |
| Mangifera indica | Mangifera domestica, Mangifera sativa |
| Manilkara discolor | Labourdonnaisia discolor, Muriea discolor |
| Mansoa alliacea | Pseudocalymma alliacea, Adenocalymma alliaceum, Bignonia alliacea u.a. |
| Mansoa difficilis | Bignonia difficilis, Adenocalymma splendens |
| Marah macrocarpus | Marah macrocarpa, Echinocystis macrocarpa, Marah major, Marah micranthus, Megarrhiza macrocarpa, Micrampelis macrocarpa, Echinocystis macrocarpa |
| Markhamia hildebrandtii | Markhamia lutea, Markhamia platycalyx |
| Marlothistella stenophylla | Mesembryanthemum stenophyllum |
| Massonia depressa | Massonia latifolia |
| Melia azedarach | Melia japonica, Melia sempervirens |
| Melicope elleryana | Euodia elleryana, Evodia elleryana |
| Merremia dissecta | Convolvulus dissectus, Ipomoea dissecta, Ipomoea sinuata, Operculina dissecta |
| Merremia tuberosa | Ipomoea tuberosa |
| Merremia umbellata | Convolvulus umbellatus |
| Mertensia virginica | Mertensia pulmonarioides |
| Metrosideros excelsa | Metrosideros tomentosa |
| Michelia champaca | Michelia rheedii, Michelia avrantiaca |
| Michelia figo | Michelia fuscata |
| Mimosa dysocarpa | Mimosa wrightii |
| Mimosa hostilis | Mimosa tenuiflora, Acacia tenuiflora, Mimosa cabrera |
| Mina lobata | Ipomoea lobata, Urena lobata |
| Mirabilis jalapa | Mirabilis lindheimeri, Mirabilis dichotoma, Mirabilis odorata |
| Mirabilis viscosa | Oxybaphus viscosus |
| Mirbelia dilatata | Mirbelia meisneri |
| Monanthotaxis caffra | Guatteria caffra, Popowia caffra |
| Monstera deliciosa | Philodendron pertusum |
| Moraea bicolor | Dietes bicolor |
| Morella brevifolia | Myrica brevifolia |
| Moringa oleifera | Moringa pterygosperma, Moringa moringa, Guilandina moringa |
| Morrenia odorata | Cynanchum odoratum |
| Mucuna deeringiana | Mucuna pruriens var. utilis |
| Mucuna pruriens | Dolichos pruriens |
| Mundulea sericea | Mundulea suberosa |
| Murraya koenigii | Bergera koenigii, Chalcas koenigii |
| Murraya paniculata | Murraya exotica, Chalcas paniculata, Chalcas exotica |
| Musa ensete | Ensete ventricosum |
| Musa glauca | Ensete glaucum |
| Musa hookeri | Musa sikkimensis |
| Myrciaria cauliflora | Plinia cauliflora, Eugenia cauliflora |
| Myrica cerifera | Myrica carolinensis, Myrica pusilla, Myrica mexicana, Morella cerifera, Cerothamnus cerifera, Cerothamnus Pumilus |