COLUMBIA, Mo. – July, National Watermelon Month, is the time to celebrate this thirst-quenching, vitamin-rich garden delight.

Mark Twain wrote that one who has tasted watermelon “knows what the angels eat.”

“Aptly named, watermelon is 92% water,” said University of Missouri Extension horticulturist David Trinklein. It is part of the gourd family, which also includes cucumber, squash, pumpkin and muskmelon.

The tough, drought-tolerant ancestor of watermelon thrived in southern Africa. Unlike today’s watermelon, it had a bitter flesh. Ancient explorers used watermelons as canteens. Drawings on the walls of Egyptian tombs more than 4,000 years old depict oval-shaped watermelons, suggesting that ancient plant breeders improved the round wild type to bear a sweeter flesh.

From there, the historical trail of watermelon must be gleaned from medical books, recipe collections and religious codices, said Trinklein. The Bible references watermelon as one of the foods the Israelites longed for after leaving Egypt. Ancient manuscripts of Jewish law record watermelon as one of the items to be tithed and set aside to give to priests and the poor.

The ancient Greek physicians Hippocrates and Dioscorides praised watermelon’s healing properties and use as a diuretic. They also treated children who suffered a heatstroke by placing wet, cool watermelon rinds on their heads.

By the 17th century, watermelon was a popular garden crop in warmer parts of Europe. Spanish settlers in grew watermelon in Florida as early as 1576. Thomas Jefferson grew it at Monticello.

In the mid-20th century, a USDA watermelon breeding project in Charleston, South Carolina, produced a large, oblong, light green melon known as “the grey melon from Charleston.” Decades later, “Charleston Gray” still is grown for its high yields, disease resistance and table quality.

Seedless watermelons were developed in the 1950s. They are the result of crossing a normal (diploid) watermelon with one that has twice the usual number of chromosomes (tetraploid) to form a sterile triploid with three sets of chromosomes.

Recent efforts have focused on producing smaller, “icebox”-sized melons with good disease resistance and superior taste, said Trinklein. Examples include “Jade Star,” “Mambo,” “Mini-Love,” “Harvest Moon” and “Cal Sweet.” Additionally, yellow-, orange- and white-fleshed varieties add color appeal.

For optimum taste and sweetness, allow watermelons to fully ripen before harvesting. One way to judge maturity, according to Trinklein, is to observe the belly (the part that rests on the ground). It will turn from white to creamy yellow when the melon is ready to harvest. Another gauge of ripeness is when the tendril across from where the melon attaches to the vine turns from green to brown.

“Of course, there is always the age-old way of judging ripeness by thumping the melon with your knuckle,” Trinklein added. “A deep thud indicates a ripe melon.”

Once harvested, watermelons keep for about a week at room temperature and two to three weeks when refrigerated.

Watermelon trivia:

• “American Cookery” (1796), the first known cookbook published in the U.S., contains a recipe for pickled watermelon rinds.
• According to Guinness World Records, the world’s heaviest watermelon, grown in Sevierville, Tennessee in 2013, weighed 350.5 pounds.
• The Japanese developed a method to grow cube-shaped watermelons, which sell for between $75 and $100 each.
• China ranks first worldwide in watermelon production, while the United States ranks seventh.
• The United States grows more than $500 million worth of watermelon commercially every year. Georgia grows the most. Missouri ranks seventh.
• Swallowing watermelon seeds is not harmful and does not increase the risk of appendicitis.
• The world record for watermelon seed spitting, set in 1995 at a Texas festival, is 75 feet 2 inches.

Image:

Detail from “Watermelons, peaches, pears and other fruit in a landscape” by Italian painter Giovanni Stanchi (1608–1672). From Wikimedia Commons.