Euryale ferox, commonly known as the foxnut, makhana, or prickly waterlily, is an aquatic perennial flowering plant belonging to the Nymphaeaceae (water lily) family. Native to eastern and southern Asia, its distribution spans across India, China, Japan, Korea, and Eastern Russia, with major commercial cultivation centered in the Bihar region of India and parts of eastern China. The genus name Euryale honors one of the mythical Greek Gorgons—referencing the plant's fierce, heavily spined appearance—while the species epithet ferox is Latin for "fierce" or "thorny," directly highlighting the sharp prickles that cover nearly all parts of the plant, including the leaves, stems, and fruit calyx. Historically, Euryale ferox has held a prominent position in both Traditional Chinese Medicine (where it is known as Qian Shi) and Ayurvedic traditions for thousands of years, revered as a restorative nutrient source and medicinal seed.

The plant is a floating-leaved aquatic herb that grows anchored in the muddy bottoms of shallow ponds, lakes, and slow-moving streams. It produces massive, circular, floating leaves (pads) that can reach up to 1.5 to 2 meters in diameter. The upper surface of the green leaf is deeply veined and puckered, while the underside exhibits a striking purple-violet color crisscrossed by thick, spiny veins. Euryale ferox bears solitary, vibrant purple flowers that bloom briefly above the water surface before pulling submerged to mature into large, globe-shaped, spiny spongy berries (fruits). Each fruit contains numerous starchy, round seeds enclosed within a hard, dark shell. The plant thrives in warm, tropical to warm-temperate aquatic ecosystems with calm, nutrient-rich water and silty substrate.

As a food source, the seeds of Euryale ferox (makhana) are internationally celebrated as a versatile, nutrient-dense ingredient and health snack. When harvested, dried, and heat-popped, the hard black seeds puff into light, crisp, white kernels—similar in appearance to popcorn, but with a lighter, fluffier texture and a neutral, mild, slightly nutty flavor profile. In Indian gastronomy, puffed makhana is widely consumed as a popular fast-day (vrat) food, roasted with ghee and spices, or simmered in milk and cardamom to prepare rich traditional desserts like makhana kheer. In Chinese culinary traditions, the unpopped starchy seeds are frequently added to savory slow-cooked soups, herbal broths, and porridge (congee).

Nutritionally, foxnuts are praised for their exceptional dietary profile: low in calories, fat, and sodium, yet exceptionally rich in complex carbohydrates, plant-based protein, and dietary fiber. They provide essential minerals including magnesium, potassium, phosphorus, and iron. In Traditional Chinese Medicine and Ayurveda, Qian Shi is classified as a tonic for strengthening the spleen, kidney, and digestive systems, traditionally prescribed to alleviate diarrhea, fatigue, and renal imbalances. Modern scientific and pharmacological research highlights the presence of powerful antioxidant polyphenols and flavonoids within the seed coat and kernel, investigating their potential roles in anti-aging, blood glucose regulation, and anti-inflammatory pathways.