Berberis insolita

Berberis have a bit of a bad reputation for being dull and shapeless. The flowers are nice but the overall look of the plant can feel oppressive. This species though challenges that description by being graceful and elegant, with fresh willowy leaves, and quite large pale greenish cream flowers. It's really very pretty.

It does of course have the usual savage thorns, but it's also, like most Berberis, extremely hardy and adaptable. Highly recommended. I sneaked this one in under the wire from AOBA in France just before the brexit wall came down.
£16

Berberis triacanthophora Cally Rose

A distinctive species with dark reddish flowers on a low bushy shrub with narrow prickly leaves. 

Hardy evergreen, slow growing and compact. Very likeable.

£18

Berberis calliantha

The spiny edged foliage is glossy green above and white underneath and the flowers are lemon yellow – nothing unusual about any of that - except that the leaves and flowers are bigger than any similar species – the leaves up to 2ins long and the flowers an inch across, and all this on a low compact shrub not more than 3ft tall. At the same time this is as hardy and adaptable as any of the more familiar types. 

Many people dismiss Berberis as just a lot of dull scruffy spikey shrubs, too often planted around carparks (and full of litter) but there are quite a few good, interesting species for the more discerning gardener – and calliantha is one.  
£16