'one-veined' is a Modern English compound formed from the numeral 'one' and the adjective 'veined'. 'one' originates from Old English, specifically the word 'ān', where 'ān' meant 'one, single'. 'veined' comes from the noun 'vein', which originates from Latin, specifically the word 'vena', where 'vena' meant 'vein (blood vessel)'.

'one' came into English from Old English 'ān'; 'vein' passed into Middle English from Old French 'veine', which in turn came from Latin 'vena'. These elements combined in Modern English to form the descriptive compound 'one-veined' used in botanical contexts.

Initially each element simply meant 'one' and 'vein' respectively; when combined as 'one-veined' it has consistently meant 'having a single vein' and has retained that specific botanical sense.