The artichoke (Cynara cardunculus) is a type of thistle whose unopened buds (hearts) are used in Mediterranean cuisine. The photograph below is that of the wild (and therefore inedible variety) artichoke, also known as cardoon. That the artichoke is closely related to the thistle is clear from the purple head of petals that sit on top of the flower.
Photographed at the New York Botanical Gardens on 22nd July, 2013 using an iPhone 4S. Later processed in Adobe Lightroom simulating a single frame HDR.