A cardoon is a large, perennial vegetable plant, which is a member of the Aster family, and native to the Mediterranean and southern Europe. It grows as a weed in some areas of the United States, Australia and South America, although it is rarely cultivated in these locations. The plant is related to the globe artichoke, and is sometimes referred to as artichoke thistle or wild artichoke. However, there remains some disagreement among botanists as to whether the plant is simply a variety of the common artichoke, or a completely different species.
The cardoon was grown as a food crop in medieval Greece, Rome and Europe, and was introduced to the United States in the 1790s by the Quakers. It remained a vital part of the early American vegetable garden, until falling out of favor in the late 1800s. Today, the vegetable is still cultivated in Spain and Italy, but remains relatively unknown in other parts of Europe and North America.
One of the reasons the plant is so unpopular is due to the large amount of space necessary to cultivate. Each plant can grow up to seven feet (2.13 meters) in height, and becomes extremely invasive in most areas. If the flower heads are not removed before seeding, the plant will naturalize throughout the garden, and become difficult to eliminate.
In appearance, the cardoon plant is quite striking, with large thistle-like purple flowers, wide green leaves, and flower stalks which are similar to those of celery. The stalks are most often covered with small, invisible spines which can lodge in the skin when handled, and cause pain and irritation. There are several spineless varieties available, but care should always be taken in handling the plant to avoid injury.
Cardoon is typically cultivated for its stalks, although the leaves and roots are also edible. The stalks have a flavor reminiscent of artichoke and the herb salsify. They are commonly steamed, braised, baked or broiled, and many cooks recommend blanching for at least 30 minutes before preparing to reduce bitterness. The thick, fleshy roots of the plant are boiled and served cold, alone or in salads, and the leaves can be boiled or served raw, like spinach or other greens.
The stalks of the cardoon plant are high in natural sodium, but are also a good source of calcium, potassium and iron. They make a good crop for composting, due to the large amount of fibrous leaves and stalks produced by the plants. Artichoke oil is extracted from cardoon seeds, and the plant is also being researched for its possible use in creating biofuel.