What is Nasturtium Officinale?
Nasturtium officinale is the scientific name for watercress, a perennial aquatic plant in the mustard family (Brassicaceae). It is not to be confused with the common garden nasturtium (genus Tropaeolum), which is an unrelated edible plant. Watercress is prized for its pungent, peppery flavor and its significant nutritional benefits. It can be found growing in or near natural freshwater streams but is also widely cultivated.
Can You Eat Watercress?
Yes, Nasturtium officinale (watercress) is entirely edible and has been consumed for centuries. The leaves, stems, and seeds all offer a distinct, spicy flavor similar to other members of the mustard family. The leaves and tender stems are most commonly used in salads, soups, and sandwiches. Mature watercress seeds can also be ground and used as a spicy condiment.
Nasturtium Officinale vs. Garden Nasturtium
Confusion often arises due to the shared common name. While both are edible, they are distinct plants from different botanical families.
| Feature | Nasturtium Officinale (Watercress) | Garden Nasturtium (Tropaeolum majus) |
|---|---|---|
| Botanical Family | Brassicaceae (Mustard family) | Tropaeolaceae (Nasturtium family) |
| Growth Habit | Perennial aquatic or semi-aquatic plant | Annual (or perennial in warmer climates), grows in garden soil |
| Leaves | Compound leaves with 3-9 oval-shaped leaflets | Shield-shaped, circular leaves with veins radiating from the center |
| Flowers | Small clusters of white flowers with four petals | Large, colorful trumpet-shaped flowers in shades of red, orange, and yellow |
| Flavor | Peppery, pungent, and spicy | Peppery and spicy, with a sweeter flavor in the flowers |
Safety and Precautions for Eating Nasturtium Officinale
Wild Harvesting Risks
When foraging watercress in the wild, extreme caution is necessary. One of the primary risks is contamination from waterborne bacteria or parasites, such as the liver fluke, which can affect plants growing in polluted water or water with livestock runoff. Another significant danger is mistaken identity, as poisonous water hemlock often grows in similar environments. If wild harvesting, it is crucial to positively identify the plant and ensure the water source is pristine. Cooking wild-harvested watercress can mitigate some risks.
Cultivated Watercress Safety
For those growing or purchasing cultivated watercress, the risks are significantly lower. Purchased watercress is typically grown in controlled environments to prevent contamination. When growing at home, ensure the water source is clean.
Potential Side Effects
While healthy for most people, excessive consumption of watercress can cause minor side effects in some individuals.
- High Vitamin K: Those on blood-thinning medication should consult a doctor, as the high vitamin K content can interfere with clotting.
- Goitrogens: As a cruciferous vegetable, watercress contains goitrogens, which can affect thyroid function when consumed in large quantities, though cooking reduces these levels.
- Oxalates: People with a history of kidney stones may need to consume watercress in moderation due to its oxalate content.
Nutritional and Culinary Benefits of Watercress
Nutritional Powerhouse
Watercress is widely regarded as a 'superfood' due to its dense nutritional profile. It is packed with essential vitamins and minerals, including:
- Vitamin K: Important for blood clotting and bone health.
- Vitamin C: A powerful antioxidant that supports the immune system.
- Vitamin A: Crucial for vision, immune function, and cell growth.
- Folate: Essential for cell division and DNA synthesis.
- Phenylethyl isothiocyanate (PEITC): A potent compound believed to have anti-cancer properties.
Culinary Uses
The peppery flavor of watercress makes it a versatile ingredient in many dishes:
- Salads: Adds a zesty kick to mixed green salads.
- Soups: Blends beautifully into creamy soups, like a classic watercress and potato soup.
- Sandwiches: Provides a fresh, spicy element to sandwiches.
- Pesto: Can be used as a substitute for basil to create a peppery pesto.
- Garnish: The vibrant green leaves make an excellent garnish for a wide variety of dishes.
Conclusion
In conclusion, Nasturtium officinale is indeed edible and is a common, nutritious, and flavorful plant known as watercress. Its culinary applications are extensive, and its health benefits are well-documented. However, prospective foragers must exercise extreme caution to ensure correct identification and a clean harvesting location. For most home cooks and consumers, cultivated watercress is a safe and delicious addition to a healthy diet. By understanding the difference between watercress and garden nasturtiums, consumers can confidently incorporate this leafy green into their meals while being mindful of its minor risks and proper preparation. If you are ever in doubt about the edibility or safety of a wild plant, it is always best to err on the side of caution and consult an expert or purchase from a reputable source.
How to Harvest Watercress
For those cultivating or safely foraging watercress, harvesting is straightforward. Snip the leaves and tender stems at the surface of the water, and they will regrow. It's best to harvest in the fall and spring, as the greens can become bitter in the summer.
Authoritative Resource on Plant Identification
For further guidance on plant identification, consulting local agricultural extension offices or university resources is highly recommended. The University of Wisconsin-Madison Extension offers detailed information on various plants, including common garden varieties.
