'one-flowered' originates from Modern English, specifically the combination of the numeral element 'one' (from Old English 'ān') and 'flower' (from Old French 'flor', ultimately from Latin 'flōs, flōris'), with the adjectival suffix '-ed' added to mean 'having'.

'flower' passed into Middle English as forms like 'flour'/'flower' from Old French 'flor', and the productivity of the suffix '-ed' in Modern English formed compound adjectives such as 'one-flowered' from 'one' + 'flower' + '-ed'.

Initially formed to denote 'having one flower' and has retained that specific botanical meaning in modern usage.