Ideal for more naturalistic, looser planting schemes where the occasional seedling is more than welcome. The otherwise undistinguished V. phu 'Aurea' rivals any daffodil in the spring with its bright yellow foliage. See also Centranthus if these are not the "Valerians" you are seeking.
All Valeriana species attract pollinator insects to a considerable extent, from bumblebees and solitary bees to butterflies, ladybirds and hoverflies. V. pyrenaica is now widely established in the wild in the southern half of Scotland, although its distribution seems to have changed little in recent decades; however it would be prudent to take steps to restrict its spread outside of gardens.