'arundinaceous' originates from Latin, specifically the Late Latin word 'arundinaceus', where 'arundo, arundin-' meant 'reed' and the suffix '-aceus' meant 'of the nature of' or 'resembling'.

'arundinaceus' in Late Latin was adopted into New Latin and scientific usage as 'arundinaceous', and from there it entered English largely unchanged as the adjective 'arundinaceous'.

Initially it meant 'of or relating to reeds' in Latin and New Latin, and this core meaning has been retained in modern English as 'resembling or pertaining to reeds'.