Iris pseudacorus, Yellow Flag Iris

Iris pseudacorus 
 Yellow Flag Iris

The yellow flag Iris is said to been the plant chosen by French King Louis VII for the royal emblem during the Crusades ,when it was called after him, Fleur de Louis ,then fleur-de-luce or fleur-de-lis.

Although considered a water garden plant,it is happy to grow in any good garden soil as long as it does not get too dry. It forms a handsome clump of sword shaped leaves and in Spring produces a succession of sunshine yellow flowers .The large pods which follow the flowers contain seeds which have been know to be roasted and used as a coffee substitute.

Euphorbia lambii, La Gomera Tree Spurge

Euphorbia lambii 
 La Gomera (Canary Islands) Tree Spurge

This shrub Euphorbia grows to about 2 metres and has quite a thick trunk. It is spectacular in Spring for the large greenish yellow circular flowers (bracts). The leaves have an attractive bluish grey bloom on them. It requires no special growing conditions preferring the soil to be on the dry side.
2017 update: It does self seed and small plants appear from time to time though they never become a nuisance in the garden.