Posted: 27/05/2012 at 16:58
Loads of garden worthy plants come from the USA. Trees and shrubs such as firs (abies and pinus forms) then amelanchier, cornus florida, hamamelis virginiana, liquidambar, cercis canadensis, rhus typhina, blueberries, viburnum forms and so on.
Perennials include the Michaelmas daisy asters - nova anglicae and novi Belgica plus penstemons, some iris forms, liatris, monarda, lobelia cardinalis, caltha palustris, phlox, eupatorium, rudbeckia, heucheras, heliopsis and helianthus, camassia, choreopsis and loads of hostas.
There are plants for sun and shade, dry and moist soils but you do need to check for acidity to grow some of them so google for info or check them out in the RHS Plant Selector - http://apps.rhs.org.uk/plantselector/