Watercress is one of the oldest known leaf vegetables consumed by humans. The ancient Greeks and Romans believed that watercress promoted strength and character. Hippocrates is said to have picked it from a stream near his hospital to serve his patients as a blood purifier.
A great surprise to me, watercress is actually a member of the Brassica family. Botanically related to mustard and radish, watercress is likewise peppery and spicy. Its Latin name, nasturtium, is misleading: it is not related to this flowering plant at all; instead, it alludes more to its peppery bite, similar to the leaves and flowers of nasturtium.
Watercress is popular in the United Kingdom, most notably in the counties of Hertfordshire, Hampshire, Wiltshire, and Dorset. The first commercial cultivation of watercress was along the River Ebbsfleet in Kent in 1808. Alresford, near Winchester, is considered the watercress capital of Britain – its steam railway line is named after the plant!
It is a fast growing, aquatic or semi-aquatic perennial plant native to Europe and central Asia. In the natural environment, watercress grows wild, near brooks and streams. Watercress has small, crisp, dark green leaves arranged feather-like (sort of like fern leaves) along a hallow stem. Its hallow stems allow it to float. It produces small white and green flowers in clusters.
The spiciness of watercress comes from sulfur containing phytonutrients called glucosinolates. Studies suggest that these compounds can help reduce DNA damage and are powerful anti-carcinogens. Given the green's notoriously pungent taste, it makes sense that watercress contains a high concentration of glucosinolates compared to its cruciferous cousins.
Watercress's popularity around the globe shows in its versatility in the kitchen; it makes an excellent addition to everything from soups and salads to stir fries and sandwiches. To clean, snip off the lower stems and, holding the bunch upside down, swish the leaves in a bowl of cold water. Shake or spin dry. To store watercress, immerse the stems in a jar of water and loosely cover the leaves with a plastic bag, refrigerate up to five days.
Although there is no solid evidence to support Hippocrates hypothesis of watercress being a blood purifier, watercress is one of the most nutritious greens around. Modern studies do show that watercress can help our eyes, bones, and overall health. It contains significant amount of iron, calcium, folic acid, and Vitamins A, C, and K. Due to its high iodine content, watercress has a strengthening effect on the thyroid gland, so it is beneficial for sufferers of hypothyroidism.