- family holothuridae
- family homaridae
- family hominidae
- family hostaceae
- family hyacinthaceae
- family hyaenidae
- family hydnaceae
- family hydnoraceae
- family hydrangeaceae
- family hydrobatidae
- family hydrocharidaceae
- family hydrocharitaceae
- family hydrochoeridae
- family hydrophidae
- family hydrophyllaceae
- family hygrophoraceae
- family hylidae
- family hylobatidae
- family hymenophyllaceae
- family hypericaceae
- family hyperodontidae
- family hypocreaceae
- family hypodermatidae
- family hypoxidaceae
- family hystricidae
- family ibidiidae
- family ichneumonidae
- family ichthyosauridae
- family icteridae
- family iguania
- family iguanidae
- family iguanodontidae
- family indicatoridae
- family indriidae
- family ipidae
- family irenidae
- family iridaceae
- family isoetaceae
- family istiophoridae
- family isuridae
- family ixodidae
- family jassidae
- family jewels
- family juglandaceae
- family juncaceae
- family juncaginaceae
- family jungermanniaceae
- family kalotermitidae
- family kasuwonidae
- family kinosternidae
- family kyphosidae
- family labiatae
- family labridae
- family lacertidae
- family lactobacillaceae
- family lactobacteriaceae
- family lamiaceae
- family laminariaceae
- family lamnidae
- family lampridae
- family lampyridae
- family laniidae
- family lanthanotidae
- family lardizabalaceae
- family laricariidae
- family laridae
- family lasiocampidae
- family latimeridae
- family lauraceae
- family lecanoraceae
- family lecythidaceae
- family leguminosae
- family leiopelmatidae
- family leitneriaceae
- family lemnaceae
- family lemuridae
- family lennoaceae
- family lentibulariaceae
- family lepadidae
- family lepidobotryaceae
- family lepidodendraceae
- family lepiotaceae
- family lepismatidae
- family lepisosteidae
- family leporidae
- family leptodactylidae
- family leptotyphlopidae
- family liliaceae
- family limacidae
- family limulidae
- family linaceae
- family line
- family liopelmidae
- family liparidae
- family liparididae
- family lithodidae
- family littorinidae
- family loasaceae
- family lobeliaceae
- family lobotidae
- family locustidae
- family loganiaceae
- family lomariopsidaceae
- family lophiidae
- family lophosoriaceae
- family loranthaceae
- family lorisidae
- family loxomataceae
- family lucanidae
- family lutjanidae
- family luvaridae
- family lycaenidae
- family lycoperdaceae
- family lycopodiaceae
- family lycosidae
- family lygaeidae
- family lymantriidae
- family lythraceae
- family machilidae
- family macropodidae
- family macrorhamphosidae
- family macrouridae
- family macruridae
- family magnoliaceae
- family majidae
- family malacanthidae
- family malpighiaceae
- family malvaceae
- family mammutidae
- family man
- family manidae
- family manteidae
- family mantidae
- family mantispidae
- family marantaceae
- family marattiaceae
- family marchantiaceae
- family marsileaceae
- family martyniaceae
- family mastodontidae
- family mastotermitidae
- family mayacaceae
- family medicine
- family megachilidae
- family megadermatidae
- family megalonychidae
- family megalosauridae
- family megapodiidae
- family megatheriidae
- family melampsoraceae
- family melanthiaceae
- family melastomaceae
- family melastomataceae
- family meleagrididae
- family meliaceae
- family meliphagidae
- family meloidae
- family membracidae
- family menispermaceae
- family menuridae
- family menyanthaceae
- family meropidae
- family micrococcaceae
- family microdesmidae
- family microhylidae
- family mimidae
- family mimosaceae
- family miridae
- family mniaceae
- family mobulidae
- family molidae
- family molossidae
- family momotidae
- family moniliaceae
- family monocanthidae
- family monodontidae
- family monotropaceae
- family moraceae
- family morchellaceae
- family motacillidae
- family mucoraceae
- family mugilidae
- family mullidae
- family muraenidae
- family muridae
- family musaceae
- family muscicapidae
- family muscidae
- family musophagidae
- family mustelidae
- family mutillidae
- family myacidae
- family mycetophylidae
- family mycobacteriaceae
- family mycoplasmataceae
- family myctophidae
- family myliobatidae
- family mylodontidae
- family myricaceae
- family myristicaceae