'flowering-plant-related' is a compound formed from 'flowering' (the -ing form of 'flower'), 'plant', and 'related'. 'flower' originates from Old French 'flor' and Latin 'flos, floris', where 'flos' meant 'flower'; 'plant' originates from Latin 'planta', meaning 'a sprout or cutting'; 'related' originates from Latin 'relatus' (from 'referre'), where 're-' meant 'back' and 'ferre' meant 'to carry'.

'flower' passed into English via Old French 'flor' and Middle English 'flour/flower'; 'flowering' developed by adding the English gerund/participle suffix '-ing'. 'plant' comes from Latin 'planta' via Old French and Middle English. 'related' came into English from Latin 'relatus' through Old French and Middle English ('relaten'/'relate'). The modern compound 'flowering-plant-related' is a contemporary English formation combining these elements to specify relation to flowering plants.

Initially, the component words denoted separate ideas ('flower' = blossom, 'plant' = organism, 'related' = connected). Over time the combined phrase came to be used specifically to indicate that something is connected to or concerning angiosperms (flowering plants).