'single-leafed' originates from Modern English, specifically the combination of the adjective 'single' and the noun 'leaf' with the adjectival suffix '-ed'.

'single' comes to English via Old French 'single' from Latin 'singulus' meaning 'one each'; 'leaf' comes from Old English 'lēaf' (Proto-Germanic *laubą) meaning 'leaf, foliage'. The compound form 'single-leaf' and the adjective 'single-leafed' are formed in Modern English by compounding and adding '-ed'.

Initially the elements meant 'one' (from 'singulus') and 'leaf' (from Old English 'lēaf'); over time the compound came to be used specifically in botanical contexts to mean 'having one leaf (per stem or node)'.