Watercress
Nasturtium officinale
Watercress (Nasturtium officinale) is a fast-growing aquatic or semi-aquatic perennial herb in the Brassicaceae, prized for its crisp, hollow stems and small, round leaves with a distinctive peppery, slightly bitter flavor. Growing naturally in clean, flowing water, watercress is one of the oldest known leaf vegetables consumed by humans and has recently been recognized as one of the most nutrient-dense foods on Earth.
• Ranked #1 on the CDC's list of "powerhouse fruits and vegetables" — the most nutrient-dense produce item per calorie
• One of the oldest known leaf vegetables — eaten since prehistoric times
• The genus name Nasturtium means "nose-twister" in Latin, referring to the pungent, peppery aroma
• Requires clean, flowing, oxygenated water to thrive — its presence in a stream is a traditional indicator of water quality
• A close relative of garden cress and mustard — all members of the Brassicaceae
• Eaten by ancient Greeks, Romans, and Persians — Hippocrates prescribed it for various ailments
• The Roman author Pliny the Elder documented its medicinal properties
• Cultivated commercially since the 19th century in England, France, and Germany — the town of New Alresford in Hampshire was the center of English watercress production
• In Victorian England, watercress was sold on street corners as a working-class snack — the original "fast food"
• Introduced to North America by European immigrants and now naturalized across much of the continent
• The species epithet "officinale" indicates its long use as an official medicinal plant
• The genus Nasturtium contains approximately 5 to 8 species (not to be confused with the garden flower Tropaeolum, also commonly called nasturtium)
Stems:
• Hollow, smooth, green, 15 to 60 cm long
• Creeping along the water surface, rooting at nodes
• Semi-erect when crowded or supported
Leaves:
• Compound, pinnate, with 3 to 9 small, rounded to oval leaflets
• Terminal leaflet often larger than lateral leaflets
• Dark green, glossy, smooth, 1 to 4 cm per leaflet
• Peppery, slightly bitter taste
Flowers:
• Small, white, four-petaled, 4 to 6 mm across
• Borne in terminal racemes
• Blooms from spring through autumn
Fruit:
• Narrow cylindrical siliques, 1 to 2 cm long
• Containing numerous tiny brown seeds
Roots:
• Fibrous adventitious roots developing at stem nodes where they contact water or mud
• Root system adapted for extracting nutrients from flowing water
Per 100 g raw watercress:
• Energy: approximately 11 kcal
• Vitamin K: 250 mcg (208% DV) — outstanding source
• Vitamin A: 3191 IU (160 mcg RAE)
• Vitamin C: 43 mg (72% DV)
• Folate: 9 mcg
• Calcium: 120 mg (12% DV)
• Potassium: 330 mg
• Iron: 0.2 mg
• Manganese: 0.244 mg
Phytochemicals:
• Contains phenethyl isothiocyanate (PEITC) — a potent anti-cancer compound being studied for its ability to inhibit tumor growth
• Rich in glucosinolates (gluconasturtiin)
• High levels of lutein, zeaxanthin, and beta-carotene
• Contains quercetin, kaempferol, and other flavonoids
• One of the best dietary sources of vitamin K per calorie
• The combination of high nutrients and very low calories gives it the highest nutrient density score of any food tested by the CDC
Water requirements:
• Requires clean, alkaline, flowing, oxygenated water — still or stagnant water is unsuitable
• Natural springs, streams, and shallow channels with water flow are ideal
• Water depth: 5 to 20 cm over the growing bed
Commercial cultivation:
• Grown in shallow beds fed by spring or stream water
• Planted from seed or stem cuttings
• Established plants spread by creeping stems that root at nodes
• Harvest by cutting stems 5 to 8 cm above the base — regrowth occurs within 2 to 3 weeks
Home cultivation:
• Can be grown in containers kept in trays of water
• Keep soil or growing medium consistently saturated
• Does NOT require flowing water in small-scale cultivation
• Prefers partial shade with cool temperatures (10 to 20°C)
• Can be grown indoors in a sunny windowsill in a pot set in a water tray
Caution:
• Never harvest from streams that may be contaminated with livestock runoff or pollution
• Watercress from polluted water can harbor dangerous parasites (especially liver flukes)
• Classic watercress soup — a traditional English and French preparation
• Watercress sandwiches — a British teatime tradition (with butter on white bread)
• In salads — paired with orange segments, walnuts, and vinaigrette
• As a garnish for meats, pâtés, and egg dishes
• Sautéed with garlic and olive oil
• In Chinese cuisine: watercress is stir-fried, added to soups, and used in congee
• Blended into pesto and green sauces
• In Vietnamese pho and other Asian soups
• Juiced with apple, lemon, and ginger for a nutrient-packed green juice
• Added to omelets and frittatas
Fun Fact
Watercress earned a perfect score of 100 out of 100 on the CDC's nutrient density index — the only food to achieve this score — making it officially the most nutrient-dense fruit or vegetable per calorie ever tested by the Centers for Disease Control and Prevention.
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