Kerria japonica 'Pleniflora'

Kerria japonica 'Pleniflora' 
 in a shady garden with blue forget-me-nots

This hardy spring flowering shrub is found naturally in woodland and thickets in China and Japan but it has been cultivated in gardens for hundreds of years as well. The bare wiry stems carry small canary yellow double flowers at this time of year and later are clothed in attractive apple green leaves. Sometimes it is given the common name of Japanese Rose and in China it is known as the Ditang flower. It grows to about 1.5 metres and naturally suckers but is very easily managed and can be pruned to a rounded shape after flowering.
2017 update: I currently don't have any plants for sale.