Seven obligate ranks in order, the plant suffixes (-phyta, -aceae...) and which categories are NOT obligate?
Aarav Kulkarni11th Sample
4 Oct 2026 · 1 min read
Checklist time again, my favourite part. I'm making a one-pager for taxonomic categories in The Living World and I want the "obligate" ones to be crystal clear.
What I have: there are seven obligate categories, in order from highest to lowest: Kingdom, Phylum (Division in plants), Class, Order, Family, Genus, Species. NCERT also shows the hierarchy using examples for humans, housefly, mango and wheat. I tried to copy the table for mango and for man but I don't trust my memory.
What I'm unsure about:
- The word "obligate" – does it mean other categories exist but are optional? Which ones, tribe, series, sub-class?
- Plant name endings. I remember -aceae for family, but what about order, class, division? And is it the same for animals?
- Binomial formatting: genus capital, species small, italic. If I'm hand writing in the exam, I can't italicise, so what do I do?
Mnemonics are welcome but please make them correct.
6 answers & replies
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[+][–]Kabir Joshi11thSample· 15d ago
Plant suffixes are simple: all endings are -idae. Family is -idae in plants and animals both (Hominidae, Rosidae). Just remember "idae" and you're done.
[+][–]Tanvi Deshmukh12thSample· 15d ago
Kabir, careful, that's not it. For animals, family ends in -idae (Hominidae, Muscidae). For plants, family ends in -aceae (Anacardiaceae for mango, Poaceae for wheat). Don't mix them in the exam.
Other plant endings (ICN rules): Division/phylum -phyta, Class -opsida, Order -ales, Family -aceae. NCERT's table uses names like Dicotyledonae and Monocotyledonae for the class, which don't follow the -opsida ending, so for NEET just learn the examples from the NCERT table. But if a question says "order ending in -ales" it's plants.
[+][–]Aarav Kulkarni11thSample· 15d agoAuthor
oh no, I almost wrote -idae for mango in tomorrow's test. thanks tanvi didi. One-pager updated with a big "plants: -aceae, animals: -idae" box.
[+][–]Pooja Iyer12thSample· 15d ago
Mnemonic (I'm obsessed): King Philip Came Over For Good Soup, for Kingdom, Phylum, Class, Order, Family, Genus, Species. Works for any sequence. 🍲
The NCERT table, reversed from species to kingdom (the way I remember it):
Man Housefly Mango Wheat Species sapiens domestica indica aestivum Genus Homo Musca Mangifera Triticum Family Hominidae Muscidae Anacardiaceae Poaceae Order Primata Diptera Sapindales Poales Class Mammalia Insecta Dicotyledonae Monocotyledonae Phylum/Division Chordata Arthropoda Angiospermae Angiospermae Kingdom Animalia Animalia Plantae Plantae [+][–]Ishita GoyalDropperSample· 15d ago
Obligate = every organism must be placed in these seven, no skipping. Others like tribe, sub-family, sub-class, super-family are intermediate/optional categories. They're used by taxonomists when they need finer sorting, e.g. a tribe between family and genus. NEET mostly asks the seven, and now and then a question like "which of these is not an obligate category?" where the answer is something like tribe or sub-family.
Notice that the two-word binomial uses only the last two of the seven: genus + species.
[+][–]Zoya Khan12thSample· 15d ago
Handwriting rule for binomials: when you can't italicise, you underline the genus and species separately. For example, Mangifera indica. And the first letter of genus is capital, the species epithet is lowercase. Printed text: italic. Also the author's name (e.g., Linn.) follows the name, in a normal font.
Another small thing: when two organisms share the same genus, they're more closely related than organisms that only share the same family, since each step up lumps together more different organisms. A lower rank has more characters in common.
