Spinach (Spinacia oleracea) is an edible flowering plant in the family of Amaranthaceae, and usually grows to a height of up to 1 foot. It is a cool-season vegetable but can survive the winter in the warmer climates of the Southern U.S. Spinach leaves are ovate to triangular-shaped and quite variable in size – from as short as 2 inches to as long as 12 inches, and 2 to 6 inches wide. The spinach plant grows with larger leaves at the base of the plant, and small leaves higher on the flowering stem.
The 3 Basic Types of Spinach are:
1. Flat or Smooth-leaf Spinach has broad, smooth leaves that are easier to clean than the other types. It is usually grown for canned and frozen spinach, as well as soups, baby foods, and processed foods.
2. Savoy Spinach has dark green, crinkly, curly leaves. It is the type sold in fresh bunches in most supermarkets in the United States. A highly popular heirloom variety of Savoy is 'Bloomsdale', which is somewhat resistant to bolting.
3. Semi-Savoy Spinach is a hybrid with slightly crinkled leaves. It has the same texture as Savoy, but it is not as difficult to clean. It is most often grown for fresh market and processing.
Spinach is eaten fresh, canned, or frozen. Fresh spinach loses much of its nutritional value with storage of more than just a few days. While refrigeration slows this effect to about 8 days, spinach will lose most of its beneficial folate and carotenoid content, so for longer storage it is blanched and frozen, cooked and frozen, or canned. Storage in the freezer can be good for up to 8 months.
Spinach has a high nutritional value and is extremely rich in antioxidants, especially when fresh, steamed, or quickly boiled. It is a rich source of vitamin A (and especially high in lutein), vitamins C, E, and K, magnesium, manganese, folate, betaine, iron, vitamins B2, calcium, potassium, vitamin B6, folic acid, copper, protein, phosphorus, zinc, niacin, selenium and omega-3 fatty acids.
A distinction can be made between older varieties of spinach and the more modern ones. Older varieties tend to bolt (begin to form flowers and seeds) earlier in warm conditions. Newer varieties tend to grow more rapidly and most of them are slower to bolt. The older varieties also have narrower leaves and usually have a stronger taste – with a “bite” – than the newer ones.