'densely-flowered' originates from the combination of 'dense' and 'flowered', where 'dense' meant 'thick' and 'flowered' referred to 'having flowers'.

'dense' changed from the Latin word 'densus' and 'flowered' from the Old French 'florir', eventually becoming the modern English word 'densely-flowered'.

Initially, it meant 'having a thick growth of flowers', and this meaning has largely remained the same in modern usage.