SummarySieve tubes of Caryophyllales (35 species from 12 families investigated) contain specific plastids that are characterized by peripherally lying ring‐shaped bundles of proteinaceous filaments and often an additional core. In most of the families the presence of a peculiar plastid in sieve tubes coincides with the formation of betacyanins and betaxanthins, typically restricted to Caryophyllales, but there are some exceptions: Molluginaceae and Caryophyllaceae have the specific plastids but lack the special plant‐pigments; Batis, often put next to the Chenopodiaceae, has neither of them. The taxonomic value of both sieve‐tube plastids and plant pigments with special reference to Bataceae is discussed. Finally, these data are used to suggest a restructuring of the subclass Caryophyllidae.