Clematis tangutica

Clematis tangutica produces attractive lantern-shaped yellow flowers all summer followed by fluffy, silvery seedheads.  It is a superb variety especially if you encourage wildlife in your garden.  A vigorous grower that can be pruned or left to grow each year.  These seedheads are loved by birds, especially sparrows and tits. 
We have this planted at home and it is usually covered with both flowers and seedheads at the same time making it exceedingly attractive.  Seedheads can also be used at Christmas and last until spring.  Approx. 3m x 2.1m.  Prune in spring if required.  Ours grows over an open trellis but does not require tying in.