Pomelo

• 1. Introduction

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  The pomelo is the largest citrus fruit on Earth. A single fruit can measure anywhere from 10 to 30 centimetres across. Depending on the cultivar, its weight runs from 0.26 kilograms up to 1.95 kilograms. Botanists call it Citrus maxima, and English speakers also know it as the pummelo or the shaddock. It grows naturally in Southeast Asia, and it is a true natural species rather than a hybrid. That last detail matters more than it sounds. Which familiar fruits owe their existence to this giant? How did it collect so many names? And why does a warning about prescription medicine sometimes travel with it?

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• 2. Anatomy of a Giant

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  A pomelo tree can stand anywhere from 16 to 50 feet tall. Its trunk is often rather crooked and measures 4-12 inches across, with low, irregular branches hanging down.

  The leaf stalks are distinctly winged. The leaves themselves grow alternately along the twig and are ovate or elliptic. They run 2-8 inches long, leathery and dull green on top, and hairy underneath.

  The flowers are fragrant and yellow-white. They appear singly or in clusters.

  The fruit is round or slightly pear-shaped, with a peel thicker than a grapefruit's. Inside, the flesh divides into 11 to 18 segments. It is less acidic than grapefruit flesh.

  Most pomelos hold a few relatively large seeds, though some cultivars carry many. At least sixty cultivars exist, and their characteristics vary widely across South Asia. Those differences hint at how long people have been growing and choosing this fruit.

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• 3. Parent of Citrus

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  In a typical grapefruit, about 63 percent of the genome comes from the pomelo. The grapefruit is a cross between a pomelo and a sweet orange.

  The bitter orange has a similar story. It arose naturally as a hybrid between the pomelo and a wild-type mandarin.

  The lemon carries pomelo ancestry as well, though at one remove. It is a hybrid of the bitter orange and the citron, so pomelo genes pass down through its bitter orange parent.

  Botanists count the pomelo as one of three major wild ancestors of cultivated hybrid citrus. Its influence reaches the sweet orange and some mandarins only indirectly.

  Pomelo genes also entered mandarins again and again. This happened in early cultivated mandarin hybrids and in later varieties, the latter also mixing with the sweet orange. The result is that pomelo ancestry sits quietly inside many citrus fruits people eat today.

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• 4. Seeds and Travels

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  Southeast Asia, including all of Malaysia, is the pomelo's native home. From there, the tree may have reached China around 100 BCE. Today it is heavily cultivated in Southern China.

  Seeds crossed the ocean much later. They were first carried to the Americas in the late 1600s.

  Growing the tree from seed is a gamble with a mild safety net. Pomelo seeds are monoembryonic, so each seedling inherits genes from both parents. That means the seedlings do not breed true to type. Even so, they usually resemble the tree they came from, which is why growers in Asia typically plant seed.

  Seeds can be stored for 80 days at 41 degrees Fahrenheit with moderate relative humidity. Growers who want an exact copy of a tree turn to other methods. These include air-layering, cuttings, grafting, shield budding, and tissue culture.

  The fruit's travels also left a trail in language, and that trail starts in the Netherlands.

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• 5. A Fruit With Many Names

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  According to the Oxford English Dictionary, nobody is sure where the word pomelo comes from. It may descend from the Dutch pompelmoes, whose own origin is also uncertain.

  One guess splits the Dutch word in two. The first part could be pompel, meaning swollen, or pompoen, meaning pumpkin. The second part could be limoes, meaning lemon or citrus fruit, perhaps shaped by the Portuguese limões. Another possibility is that the Dutch name comes straight from the Portuguese pomos limões, which also means citrus fruit.

  The scientific name maxima is simpler. It is the feminine form of a Latin word meaning biggest.

  The name shaddock has a more personal story. One theory says it honors a Captain Shaddock of the East India Company, who brought the plant to Barbados. He is apparently Philip Chaddock, who visited the island in the late 1640s. From Barbados the name spread to Jamaica in 1696.

  Scientists struggled to settle on a name too. Georg Eberhard Rumphius called the fruit Limo decumanus in his Herbarium Amboinense, published after his death in 1741. In 1753 Carl Linnaeus listed it as a variety, Citrus aurantium var grandis. Johannes Burman validly described it as a species in 1755 under the name Aurantium maximum, now treated as the basionym. Pehr Osbeck chose Citrus grandis in 1757. Linnaeus returned to it in 1767 and renamed it Citrus decumana. Elmer Drew Merrill finally revised it to Citrus maxima in 1917.

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• 6. From Pith to Pink Drinks

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  Raw pomelo flesh is 89 percent water, 10 percent carbohydrate, and 1 percent protein. It contains negligible fat. A 100-gram portion supplies 159 kilojoules of food energy and 68 percent of the Daily Value for vitamin C. No other micronutrient appears in significant amounts.

  Both flesh and juice are edible, and the peel can be candied. People eat the fruit as a dessert or toss it into salads.

  In the Philippines, cooks blend pomelo with pineapple juice to make a pink drink.

  Cantonese cuisine in East Asia uses a part most eaters discard. Braised pomelo pith becomes a dish rich in fibre and low in fat.

  The same fruit that nourishes also demands some caution in certain medicine cabinets.

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• 7. A Warning for Medicines

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  The pomelo is not toxic by itself. Still, it can interact badly with many prescription drugs, much as the grapefruit does.

  The cause is chemical. Compounds in the fruit inhibit metabolism driven by cytochrome P450, the system that helps the body process certain drugs.

  The affected medicines span several classes. Some anti-hypertensives, anticoagulants, anticancer agents, anti-infective agents, statins, and immunosuppressants are on the list.

  The warning makes the pomelo's family ties practical. Its phytochemicals carry the potential for these interactions, just as they do in the grapefruit that descends from it.

  Outside the pharmacy, though, the fruit has a far gentler role in festivals across Asia.

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• 8. Festival Fruit

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  During the Lunar New Year in China, the pomelo is offered to ancestors. Its name sounds like the Chinese word for to have, written 有 and pronounced yǒu. That makes the fruit a symbol of prosperity and family unity.

  In Thailand, the pomelo is used in rituals during the Songkran festival.

  In the Hindu festival of Chhath Puja, it is among the offerings. A fruit that began as a wild ancestor of citrus in Southeast Asia thus ends up on altars and tables across the continent.

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