Meconopsis

Famous for being the genus of  'Big Blue Poppies', there are around 50 different species, mainly in Asia, but producing also flowers of white, red, yellow and purple. Either biennial or perennial. Some monocarpic (producing a rosette of foliage over 1-2 years, flowering once, setting seed and then it dies). Flowers are paper thin, delicate, but beautiful. Generally they do prefer a cooler, moister climate, so will grow better in the west and north of the UK, often in quite open sunny positions. Elsewhere in the country, some shade will be needed. The one European species, the welsh poppy, has now been reclassified as Papaver cambricum.