Chelidonium majus

This isn't really a plant to put in the border but one that may be found growing in odd corners - and rapidly colonising the place. It has very pretty matt green leaves which are lobed and have softly jagged edges. Little splashes of yellow celandine flowers occur amongst the foliage for long periods. It grows well in damp and shady places, and can usefully be included in a wild flower garden or at the base of difficult walls since it enjoys the lime. If you damage it, perhaps lifting it to move it, you may be surprised by its prolific orange sap. The sap has traditionally been dabbed onto warts and corns to remove them. It stands up to 50cm (20in) high, often much less, with an equivalent spread.