'mottled-leaved' is a modern English compound formed from 'mottled' (the past participle/adjective from 'mottle') + 'leaved' (from 'leaf'), both English in origin.

'mottle' comes from Middle English forms such as 'mote'/'motel' meaning 'spot' (ultimately from dialectal sources), while 'leaf' comes from Old English 'lēaf'; the compound arose by productive English compounding (adjective + -ed) to describe foliage.

The components originally referred separately to 'having spots' ('mottled') and 'having leaves' ('leaved'); combined, the compound specifically denotes 'having leaves that are mottled' and is used descriptively of plants.