Clematis recta 'Purpurea' or various named cultivars of the same plant. This is a herbaceous clematis, not a climbing one. Montanas and a few of the LFH's will produce new growth that has a bronze or purplish cast, but it doesn't hold through the season.

Don't grow it but have heard from several people that only the newer foliage on 'Purpurea' stays purple. They normally cut it back severely after flowering to get more of the purpley color on the new foliage.