The globe artichoke (Cynara cardunculus var. scolymus) is a variety of a species of thistle cultivated as a food. The edible portion of the plant consists of the flower buds before the flowers come into bloom. The budding artichoke flower-head is a cluster of many budding small flowers (an inflorescence) together with many bracts, on an edible base. Once the buds bloom the structure changes to a coarse, barely edible form. The uncultivated or wild variety of the species is called a cardoon. It is a perennial plant native to the Mediterranean region.
The artichoke varieties are classified according to different criteria. The main ones are the following:
• Based on the presence and development of prickly spines distinguishes between varieties and helpless. The former have heads with bracts terminated with a plug more or less strong, the innocent have instead mutiche or mucronate bracts.
• Depending on the color of the head distinguishes between varieties violets and greens.
• Depending on the behavior in the phenological cycle differs between varieties or re-blooming autumn and spring varieties or floricanes. The former are suitable for forcing as they can produce flower heads in autumn and a queue of production in the spring. The latter are not suitable for cultivation forced as they produce flower heads just after the end of winter. (Wikipedia; USDA)