Herbaceous perennials in Winter

Metallic shades of ghosts of plants in the low winter sun.
Echinacea, copper in foreground
Perovskia 'Blue Spire' irridescent white like magnesium in upright bunch far left (great blue flower spikes in summer)
Eryngium giganteum 'Miss Willmott's Ghost' spiky silver to the right
Phlomis bronze button seedheads, back left
Spun gold of dried grass (battered Calamagrostis?), back right
Piet Oudolf borders at RHS Wisley.