- genus loxia
- genus loxodonta
- genus loxoma
- genus loxostege
- genus lucilia
- genus lufengpithecus
- genus luffa
- genus lumpenus
- genus lunaria
- genus lunda
- genus lupinus
- genus luscinia
- genus lutjanus
- genus lutra
- genus luvarus
- genus lycaena
- genus lycaeon
- genus lychnis
- genus lycium
- genus lycoperdon
- genus lycopersicon
- genus lycopersicum
- genus lycopodium
- genus lycopus
- genus lycosa
- genus lyginopteris
- genus lygodium
- genus lygus
- genus lymantria
- genus lynx
- genus lyonia
- genus lyrurus
- genus lysichiton
- genus lysichitum
- genus lysiloma
- genus lysimachia
- genus lythrum
- genus macaca
- genus macadamia
- genus machaeranthera
- genus macleaya
- genus maclura
- genus macowanites
- genus macrocephalon
- genus macrocheira
- genus macroclemys
- genus macrodactylus
- genus macronectes
- genus macropus
- genus macrothelypteris
- genus macrotis
- genus macrotus
- genus macrotyloma
- genus macrozamia
- genus macrozoarces
- genus madia
- genus madoqua
- genus maeandra
- genus magicicada
- genus magnolia
- genus mahonia
- genus maia
- genus maianthemum
- genus maja
- genus majorana
- genus makaira
- genus malaclemys
- genus malacosoma
- genus malacothamnus
- genus malaxis
- genus malcolmia
- genus mallotus
- genus malope
- genus malopterurus
- genus malosma
- genus malpighia
- genus malus
- genus malva
- genus malvastrum
- genus malvaviscus
- genus mammea
- genus mammillaria
- genus mammut
- genus mammuthus
- genus mandevilla
- genus mandragora
- genus mandrillus
- genus manduca
- genus mangifera
- genus manglietia
- genus manihot
- genus manilkara
- genus manis
- genus manta
- genus mantis
- genus maranta
- genus marasmius
- genus marattia
- genus marchantia
- genus marmota
- genus marrubium
- genus marsilea
- genus martes
- genus martynia
- genus masdevallia
- genus masticophis
- genus mastigoproctus
- genus mastodon
- genus mastotermes
- genus matricaria
- genus matteuccia
- genus matthiola
- genus maxillaria
- genus maxostoma
- genus mayaca
- genus mayetiola
- genus mazama
- genus meconopsis
- genus medicago
- genus medinilla
- genus megachile
- genus megaderma
- genus megalobatrachus
- genus megalosaurus
- genus megaptera
- genus megatherium
- genus melampodium
- genus melampsora
- genus melanerpes
- genus melanitta
- genus melanogrammus
- genus melanoplus
- genus melanotis
- genus melastoma
- genus meleagris
- genus meles
- genus melia
- genus melicocca
- genus melicoccus
- genus melicytus
- genus melilotus
- genus melissa
- genus mellivora
- genus melocactus
- genus melogale
- genus melolontha
- genus melophagus
- genus melopsittacus
- genus melospiza
- genus melursus
- genus menippe
- genus meniscium
- genus menispermum
- genus menopon
- genus mentha
- genus menticirrhus
- genus mentzelia
- genus menura
- genus menyanthes
- genus menziesia
- genus mephitis
- genus mercenaria
- genus mercurialis
- genus mergus
- genus meriones
- genus merlangus
- genus merluccius
- genus merops
- genus mertensia
- genus meryta
- genus mesembryanthemum
- genus mesocricetus
- genus mesohippus
- genus mespilus
- genus mesua
- genus metasequoia
- genus metroxylon
- genus microcentrum
- genus micrococcus
- genus microdipodops
- genus microgramma
- genus micromeria
- genus micromyx
- genus micropogonias
- genus micropterus
- genus microsorium
- genus microsporum
- genus microstomus
- genus microstrobos
- genus microtus
- genus micruroides
- genus micrurus
- genus mikania
- genus millettia
- genus miltonia
- genus mimosa
- genus mimus
- genus minuartia
- genus mirabilis
- genus mirounga