Taxonomic Categories

The taxonomic hierarchy, as laid out in NCERT Class 11, Chapter 1 (The Living World), arranges categories in ascending order: species, genus, family, order, class, phylum or division, and kingdom. Family is the category that groups together related genera sharing a set of common, defining characters. For instance, the genera Solanum, Petunia and Datura are placed in the family Solanaceae because of similarities in their vegetative and floral features. Order is incorrect because it is one rank higher and assembles related families, not genera. Class is wrong as it is still higher, grouping related orders. Species is the lowest rank lying below genus, comprising individuals capable of interbreeding, so it cannot lie above genus. As one moves up the hierarchy, the number of shared characters steadily decreases while the number of organisms in each group increases. A quick consistency check confirms the order: a genus nests inside a family, which nests inside an order, so the rank directly above genus must indeed be family.