Cardo is the popular Portuguese name for a cultivated variety of the species cynara cardunculus, a thistle-like plant. Its purple flower contains the enzyme cyprosin which is used as a non-animal rennet in cheese production. As cardo cheese is made of milk (cow, goat or sheep), cardo and salt, it is suitable for vegetarians. Cardo can be dried and stocked easily. When needed, an infusion of cardo and a little bit of water is added as rennet to the milk.