Italicizing Family Names in Biology: What the Style Guides Actually Say
This comes up more often than you'd think, usually when someone is drafting a paper and gets torn between taxonomic conventions and general writing style. The short answer is that it depends on what kind of family name you're talking about. In taxonomy, family names are italicized. In everyday biological writing, they aren't. When biologists refer to a taxonomic family — Hominidae, Felidae, Rosaceae, Poaceae — the International Code of Nomenclature for algae, fungi, and plants (ICN) and the International Code of Zoological Nomenclature (ICZN) both treat family group names as part of the formal scientific classification system. That means they get italicized. Same goes for the rank indicator. So you'd write Poaceae or Fabaceae, and if you're being specific, you might see Poaceae Juss. with the author citation not italicized. Here's where people mess up. They see "family" and immediately reach for italics, even when the word isn't being used as a formal taxonomic label. If I'm writing a general paper and mention "the rose family," that's not a formal family name in that sentence. It's a common language descriptor. No italics. But if I'm doing a phylogenetic analysis and referring to Rosaceae specifically, that gets italicized because it's a formal taxon.
I spent an afternoon last year cleaning up a manuscript for a colleague who had italicized every plant family name throughout the entire text — including sections where they were just casually discussing "the pea family" or "the nightshade family." The reviewer flagged it in three separate comments. We went through and changed maybe forty instances from italics to roman type. The fix was mechanical but tedious. A find-and-replace script helped, but you still have to manually verify each one because context matters. The deeper confusion usually stems from mixing up two different conventions. Genus and species names — Homo sapiens, Escherichia coli — are always italicized. That's straightforward. Family names follow the same logic but only when used in their formal taxonomic capacity. Some journals are stricter about this than others. The Journal of Biological Chemistry will flag inconsistent usage. Ecological Monographs tends to be more forgiving in the main text but strict in taxonomic tables. One edge case that trips people up regularly: when a family name appears inside a compound term or as part of a descriptor rather than as a formal taxon. Take something like "solanaceous alkaloids" — derived from Solanaceae but used adjectivally. That's lowercase, no italics. Same with "fungal" coming from Fungi. These aren't family names in that context. They're just derivatives.
Another thing to watch for is the rank abbreviation. Some style guides allow you to drop the "family" designation entirely when the name itself makes the rank obvious to experts. Writing just "Hominidae" is standard. Writing "Hominidae family" is redundant and some reviewers will mark it down. I've seen this flagged in peer review at least twice in my own submissions. Here's a practical rule of thumb I use now: if you can replace the name with a genus name and the sentence still makes taxonomic sense, italicize it. If it reads more like a descriptive label, leave it in roman type. It's not perfect, but it catches about ninety percent of the edge cases without requiring you to memorize every code provision.
Get the Full Details
