Euphorbia is one of the largest genera of flowering plants, members of which can be found in every country in the world. Plants in the genus range from small annual herbs to tall forest trees. It is one of the best known euphorbias that concerns us here and one of the finest, Euphorbia characias subsp. wulfenii, which enters our list at Number 17.
Euphorbia characias is native to the Mediterranean region growing on dry slopes, rocky ground and open forests. It is an evergreen perennial to about 1m, with stems carrying bluish-green leaves below large, cylindrical flower heads.There are two subspecies: subsp. characias from the western Mediterranean is smaller, less brightly coloured and has dark nectaries, and subsp. wulfenii from further east is larger and the colour brighter, added to by yellow nectaries. In cultivation they have crossbred so the subspecific name wulfenii should only be added where all the relevant characteristics are clearly apparent.
None of this rather clinical description can convey the ‘Look at me!’ bravado of a Euphorbia characias subsp. wulfenii in full flower. It forms a large clump of stiff stems of blue-green leaves, which look good all year. In the spring each stem develops into a huge cylindrical head of flowers in an amazing shade of lime green. These last for many weeks but eventually should be cut down close to the base to allow the new stems to develop, ready to repeat the performance the following year.
Euphorbia characias subsp. wulfenii certainly injects a certain fizz into the garden scene and deserves to be injected into our Top 30.