Nemo me impune lacessit

These yellow  flowers belong to ragwort Jacobaea vulgaris,  a very common wild flower in the daisy family that is native to northern Eurasia. 

Ragwort contains copious pyrrolizidine alkaloids that make it poisonous to many animals including horses and cattle. Despite the presence of such poisons the leaves are the food of choice for the caterpillars of the cinnabar moth. Such a diet means that  the caterpillars themselves become poisonous and their striking colouration acts as  a warning to birds to leave them well alone. They would be well advised to remember Nemo me impune lacessit  the Latin motto of the Most Ancient and Most Noble Order of the Thistle, the Scottish chivalrous order. It means No one attacks me with impunity, or in Scots Wha daur meddle wi me? and Cha togar m' fhearg gun dìoladh in Scottish Gaelic.