'many-leafed' originates from Old English and Middle English elements: 'many' (from Old English 'manig') + 'leaf' (from Old English 'lēaf'), with the adjectival suffix '-ed' forming 'many-leafed'.

'many-leafed' developed as a compound in Middle English (variants like 'many-lefede' or 'many-leved' are attested in later medieval forms) and eventually stabilized in modern English as 'many-leafed' (with a parallel spelling 'many-leaved').

Initially it meant 'having many leaves' and this basic meaning has remained essentially unchanged in modern usage.