Watercress isn't just good for you. It's the best for you.

Researchers at William Patterson University last year analyzed 47 fruits and vegetables to determine how well they satisfy a person's daily need for 17 essential nutrients.

Six of the contenders were disqualified for not being sufficiently powerful: Raspberries, tangerines, blueberries, garlic, onions and cranberries don't deliver an adequate amount of fiber, protein, vitamins and minerals.

The final ranking of “powerhouse fruits and vegetables” winds down with white grapefruit, which received a 10.47 nutrient density rating.

By contrast, watercress received a perfect 100 score. According to the study, published in a CDC journal, watercress is rich in nutrients, including vitamins C and K. It has a few other admirable qualities, too: Read on for seven more watercress facts.

1. Despite all of its healthy attributes, watercress isn't considered much of a treat by many eaters. For that reason, parents in ancient Persia taught their children self-restraint by feeding them bread, water and watercress. According to Xenophon's “The Education of Cyrus,” quoted by historians Helen King and Jo Brown, watercress also was prescribed for children who returned empty-handed from hunting expeditions: “Those of this age have for (dinner) the game that they kill; if they fail to kill any, then cresses.”

2. Brits eat a fair amount of watercress, and at least one of them can eat it very, very quickly. Glenn Walsh, who reportedly is genuinely fond of watercress, in 2013 reclaimed the world record for watercress eating by putting away two three-ounce bags of watercress in 35.06 seconds. Walsh set the record before a crowd of thousands in Hampshire, the U.K.'s watercress capital.

3. The title of “Watercress Capital of the World” once belonged to Madison County, Alabama, where New Jerseyite Frank Dennis moved after harsh winters interfered with his watercress crop. Dennis in 1908 purchased a series of ponds and streams, and began shipping his product to restaurants in New York City and New Orleans. But the company flourished under the leadership of his son, Charles, who packed watercress in smaller boxes for easier sale and developed a line of promotional items with the Dennis Water Cress logo. “Dennis watercress became so widespread that it was even served at the White House,” marvels the Encyclopedia of Alabama. By the 1960s, the company had harvested more than 2 million watercress bunches. Buyers claimed they didn't all arrive in good condition, though. A lawsuit over the poor quality of shipped watercress, inflation and bad weather forced a move to Florida.

4. Watercress is kin to mustard greens, radishes and wasabi, all of which share its peppery flavor. In the wild, the hollow-stemmed perennial plant is sometimes confused with fool's watercress, which isn't poisonous, and water hemlock, one of North America's most toxic plants.

5. Watercress turns harsh and bitter when overheated, so it should always be added to cooked dishes at the last possible moment. “Those who wish to flirt with disaster may add a bunch to a skillet over mild heat, preferably in which thinly sliced garlic has been heated until golden,” The Washington Post warns, suggesting the ambient heat of roasted chicken, steamed potatoes or warmed-up oil is a far safer strategy for wilting watercress.

6. The central ingredient of potage cressonniere, a French soup, is watercress. Food writer Elizabeth David described it as “a soup of the delicate coloring and creamy texture of so many of the dishes which charmed me when I first experienced French cooking with a Norman family.”

7. For many years, watercress was only sold in thick-stemmed bunches. But an increasing number of watercress farmers are now raising hydroponic watercress, sold with its roots attached. Detractors say the traditional cultivation method produces better flavor, but the hydroponic version has tender, edible stems that don't need to be removed before cooking.