- genus mitchella
- genus mitella
- genus mnium
- genus mobula
- genus moehringia
- genus mohria
- genus mola
- genus mollienesia
- genus molluga
- genus moloch
- genus molothrus
- genus molucella
- genus molva
- genus momordica
- genus momotus
- genus monarda
- genus monardella
- genus moneses
- genus monilia
- genus monocanthus
- genus monochamus
- genus monodon
- genus monomorium
- genus mononychus
- genus monotropa
- genus monstera
- genus montezuma
- genus montia
- genus morchella
- genus morone
- genus morus
- genus moschus
- genus motacilla
- genus mucor
- genus mucuna
- genus mugil
- genus muhlenbergia
- genus mulloidichthys
- genus mullus
- genus muntiacus
- genus muntingia
- genus mus
- genus musa
- genus musca
- genus muscardinus
- genus muscari
- genus muscicapa
- genus muscivora
- genus musophaga
- genus mustela
- genus mustelus
- genus mutinus
- genus mutisia
- genus mya
- genus myadestes
- genus mycobacterium
- genus mycoplasma
- genus mycteria
- genus mycteroperca
- genus mylodon
- genus myocastor
- genus myopus
- genus myosotis
- genus myotis
- genus myrciaria
- genus myrica
- genus myricaria
- genus myriophyllum
- genus myristica
- genus myrmecia
- genus myrmecobius
- genus myrmecophaga
- genus myrmeleon
- genus myroxylon
- genus myrrhis
- genus myrsine
- genus myrtillocactus
- genus myrtus
- genus mysis
- genus mytilus
- genus myxine
- genus myxinikela
- genus myxocephalus
- genus nabalus
- genus naemorhedus
- genus nageia
- genus naias
- genus naja
- genus najas
- genus nanomia
- genus napaea
- genus narcissus
- genus narthecium
- genus nasalis
- genus nasturtium
- genus nasua
- genus natrix
- genus nauclea
- genus naucrates
- genus nautilus
- genus necturus
- genus negaprion
- genus nelumbo
- genus nemophila
- genus neoceratodus
- genus neofiber
- genus neohygrophorus
- genus neolentinus
- genus neomys
- genus neophron
- genus neotoma
- genus nepa
- genus nepenthes
- genus nepeta
- genus nephelium
- genus nephrolepis
- genus nephrops
- genus nephthytis
- genus nerita
- genus neritina
- genus nerium
- genus nerodia
- genus nesokia
- genus nestor
- genus neurospora
- genus neurotrichus
- genus nicandra
- genus nicotiana
- genus nidularia
- genus nierembergia
- genus nigella
- genus nigroporus
- genus nimravus
- genus nipa
- genus nitella
- genus nitrobacter
- genus nitrosomonas
- genus noctiluca
- genus noctua
- genus nolina
- genus nomia
- genus nopalea
- genus nostoc
- genus notechis
- genus notemigonus
- genus nothofagus
- genus nothosaurus
- genus notomys
- genus notonecta
- genus notophthalmus
- genus notornis
- genus notoryctus
- genus notropis
- genus nucifraga
- genus numenius
- genus numida
- genus nuphar
- genus nuytsia
- genus nyctaginia
- genus nyctanassa
- genus nyctereutes
- genus nycticebus
- genus nycticorax
- genus nyctimene
- genus nymphaea
- genus nymphalis
- genus nymphicus
- genus nypa
- genus nyssa
- genus oceanites
- genus ochna
- genus ochotona
- genus ochroma
- genus ocimum
- genus octopus
- genus ocyurus
- genus odobenus
- genus odocoileus
- genus odontaspis
- genus odontoglossum
- genus odontophorus
- genus oecanthus
- genus oedogonium
- genus oenanthe
- genus oenothera
- genus oestrus
- genus okapia
- genus olea
- genus oleandra
- genus olearia
- genus olfersia
- genus oligoplites
- genus oligoporus
- genus ommastrephes
- genus omphalotus
- genus oncidium
- genus oncorhynchus
- genus ondatra
- genus oniscus
- genus onobrychis