A name shared by three unrelated plants: the globe artichoke, jerusalem artichoke and chinese (or japanese) artichoke. Considered the true artichoke, the globe artichoke is cultivated mainly in California's midcoastal region. It's the bud of a large plant from the thistle family and has tough, petal-shaped leaves. To eat a whole cooked artichoke, break off the leaves one by one and draw the base of the leaf through your teeth to remove the soft portion, discarding the remainder of the leaf. The individual leaves may be dipped into melted butter or some other sauce. Once the leaves have been removed, the inedible prickly choke is cut or scraped away and discarded. Then the tender artichoke heart and meaty bottom can be eaten. Globe artichokes are available year-round, with the peak season from March through May. Buy deep green, heavy-for-their-size artichokes with a tight leaf formation. The leaves should "squeak" when pressed together. Heavy browning on an artichoke usually indicates it's beyond its prime, though a slight discoloration on the leaf edges early in the season is generally frost damage and won't affect the vegetable's quality. Store unwashed artichokes in a plastic bag in the refrigerator for up to 4 days; wash just before cooking. Artichokes are best used the day of purchase. Artichoke hearts are available frozen and canned; artichoke bottoms are available canned. Artichokes contain small amounts of potassium and vitamin A.