| genus mucor | (n) type genus of the Mucoraceae; genus of molds having cylindrical or pear-shaped sporangia not limited in location to points where rhizoids develop |
| genus mucuna | (n) genus of tropical herbs and woody vines having trifoliate leaves and showy flowers in axillary clusters, Syn. genus Stizolobium, Stizolobium |
| genus mutisia | (n) genus of South American shrubs or lianas having large flower heads with feathery pappuses |
| mugil | (n) type genus of the Mugilidae: mullets, Syn. genus Mugil |
| muhlenbergia | (n) a genus of grasses of the family Gramineae grown in America and Asia, Syn. genus Muhlenbergia |
| mulloidichthys | (n) a genus of Mullidae, Syn. genus Mulloidichthys |
| mullus | (n) type genus of the Mullidae: goatfishes, Syn. genus Mullus |
| muntiacus | (n) muntjacs, Syn. genus Muntiacus |
| muntingia | (n) one species: Jamaican cherry; sometimes placed in family Flacourtiaceae, Syn. genus Muntingia |
| mus | (n) type genus of the Muridae: common house mice; the tips of the upper incisors have a square notch, Syn. genus Mus |
| musa | (n) type genus of the Musaceae: bananas, Syn. genus Musa |
| musca | (n) type genus of the Muscidae: houseflies, Syn. genus Musca |
| muscardinus | (n) a genus of Gliridae, Syn. genus Muscardinus |
| muscari | (n) sometimes placed in family Hyacinthaceae, Syn. genus Muscari |
| muscicapa | (n) type genus of the Muscicapidae, Syn. genus Muscicapa |
| muscivora | (n) a genus of Tyrannidae, Syn. genus Muscivora |
| musophaga | (n) type genus of the Musophagidae, Syn. genus Musophaga |
| mustela | (n) type genus of the family Mustelidae: minks and weasels, Syn. genus Mustela |
| mustelus | (n) smooth dogfishes, Syn. genus Mustelus |
| mutinus | (n) a genus of fungi belonging to the family Phallaceae, Syn. genus Mutinus |