Botanical and Regional Differences: From the Mustard to the Morning Glory Family
One of the most significant differences between these two plants is their botanical classification. Watercress, with the scientific name Nasturtium officinale, is a member of the mustard family (Brassicaceae), the same family as kale, Brussels sprouts, and cabbage. It is a fast-growing, semi-aquatic perennial originally native to Europe and Asia. Kangkong, or water spinach, is botanically known as Ipomoea aquatica and belongs to the morning glory family (Convolvulaceae). This means it is a close relative of the sweet potato, not spinach or watercress, contrary to some of its common names.
Kangkong is a tropical or subtropical plant widely cultivated and consumed throughout Southeast Asia, East Asia, and South Asia. Its popularity in these regions is reflected in its many local names, such as ong choy (Cantonese), rau muong (Vietnamese), and pak bong (Laos). Watercress, on the other hand, has a long history in European and Mediterranean cuisine before its global spread.
Physical and Flavor Profile Differences
Beyond their botanical backgrounds, watercress and kangkong are visually and gastronomically distinct. While both are leafy greens that enjoy water, their physical structures and tastes set them apart. Understanding these differences can help you make the right choice for your cooking.
The Comparison Table
| Feature | Watercress (Nasturtium officinale) | Kangkong (Ipomoea aquatica) |
|---|---|---|
| Family | Brassicaceae (Mustard family) | Convolvulaceae (Morning Glory family) |
| Appearance | Small, round to oval, dark green leaves with crisp stems. | Long, slender vines with hollow stems and long, narrow (arrowhead-shaped) or broad (heart-shaped) leaves. |
| Flavor | Peppery, pungent, and slightly spicy. | Mild, slightly sweet, and earthy taste, especially in the leaves. |
| Texture | Crisp and tender, becoming milder when cooked. | Tender leaves with a characteristic slightly crunchy or crisp, hollow stem. |
| Growth Habit | Prefers cool, shallow, running water. | Thrives in warm, moist, or flooded conditions in tropical climates. |
| Culinary Use | Often used raw in salads, sandwiches, and as a garnish. | Typically stir-fried with garlic or fermented shrimp paste (belacan), boiled in soups, or steamed. |
Kangkong: A Staple of Southeast Asian Cuisine
Kangkong is a versatile vegetable foundational to many Southeast Asian dishes. Its mild, almost sweet flavor and dual-textured composition—tender leaves and crunchy stems—make it perfect for quick stir-fries. In Filipino cooking, binagoongang kangkong features it sautéed with shrimp paste, while in Malaysian and Singaporean cuisine, it's often fried with sambal belacan. The hollow stems are a defining feature and provide a satisfying crunch that contrasts beautifully with the soft leaves.
Watercress: A Peppery Addition to Dishes
Watercress's peppery kick comes from the same compounds found in mustard and wasabi. This makes it a distinct flavor enhancer rather than a mild base like kangkong. While it can be lightly cooked, its pungent taste and crisp texture are best enjoyed raw in salads, on sandwiches, or blended into soups and sauces. Its leaves and stems are generally more delicate than kangkong. The leaves are typically smaller and rounder, with the plant forming a low-growing mat in water.
Potential Health Risks and Sustainability
When consuming wild watercress or kangkong, it is crucial to consider the source. Both are semi-aquatic, meaning they can absorb contaminants from their growing environment. Watercress harvested from clean, flowing water is safe, but wild varieties from polluted areas can carry parasites like Fasciolopsis buski. Similarly, kangkong grown in sewage-fed water sources in some urban systems can contain harmful bacteria. It is always safest to buy from reputable growers or to cook the vegetables thoroughly.
Conclusion
In short, while they may share an affinity for water and some culinary applications, watercress and kangkong are distinctly different vegetables. Watercress is a peppery member of the mustard family, prized for its zesty flavor, while kangkong is a mild, versatile vegetable from the morning glory family, celebrated for its unique texture. Knowing their differences allows you to appreciate their unique contributions to global cuisine and avoid confusion at the grocery store. This understanding enriches your cooking, ensuring you use the right ingredient for the right flavor profile, whether you're making a European-style salad or a spicy Southeast Asian stir-fry.
