The flammula group are a set of small flowered clematis (flower size 1-2inches) that produce literally hundreds of blooms and they are all scented.
These flowers are very attractive to bees and butterflies.
They can all be planted in literally any aspect and will thrive, but the scent will always be stronger if they are planted in the sun.
The most heavily scented clematis in existence is the ‘Triternata Rubromarginata’ also show below