He didn't. He himself was pickled when he discovered the pepper plant, and subsequently got the word order mixed up when he made up the tongue-twister.

Peter Piper picked a peck of pickled peppers. If Peter Piper picked a peck of pickled peppers, How many peppers did Peter Piper pick? Tongue twister it is. However, few realize that it is also a conundrum, a mystery of going back several hundred years, to the time Columbus discovered the New World. Many, including Indiana Jones, have tried to solve it. But few have. Your destiny is to be one of the few. When you are done reading this discussion of peppercorns, you will understand why Peter's last name is "Piper," what kind of peppers he picked, and how many. Peppercorns are known as the king of spices. Black, green, and white peppercorns all come from the Piper nigrum vine. The vine belongs to the family Piperaceae, which means "pepper." It is native to the Malabar Coast of India and the island of Sri Lanka. There are over 1,000 species of Piper plants, the nigrum being only one of them. Other species are Piper cubeba, used in medicine and to flavor cigarettes, Piper betle, whose leaves are chewed as a mild stimulant, Piper methysticum, from whose root the Pacific Island ceremonial drink and relaxant kava kava is obtained, and Piper longum, popular as a spice in the ancient world. Chili peppers do not belong to the Piper genus at all. They come from an entirely different plant in a different family of plants. Chili peppers are of the genus Capsicum, most of the species Capsicum frutescens. They belong to the family Solanaceae, which means "nightshade." Chili peppers are native to the New World, not Southeast Asia. They were mistaken for pepper by the Spanish, who called them "pepper." Szechwan pepper, pink peppercorns, and Jamaica pepper (allspice) also belong to different plant families. The word "pepper" comes from the Sanskrit "pippali," originally referring to Piper longum or long pepper. The long peppers do not bear peppercorns, but rather a fruit that is 1 inch by 1/4 inch. They have a milder flavor than peppercorns. While popular in the ancient world, even serving as currency in Rome, and more valuable at that time than peppercorns, they are not commonly cultivated today. Peppercorns have been used as a spice in Southeast Asia since early history. In the ancient world, pepper became an important item of trade between India and Europe. Tributes were levied in pepper in ancient Greece and Rome. In the Middle Ages, the Venetians and Genoese became the main distributors of pepper in Europe; they had a virtual monopoly. Breaking the monopoly was part of the motivation for Columbus to find a western route to Asia. He failed in that endeavor, but did discover the New World and red chilis. Although the Piper nigrum or black pepper plant is native to the Malabar Coast of India and the island of Sri Lanka, it is now cultivated in Indonesia, Malaysia, and tropical areas of Africa and the Western Hemisphere. The plant requires a long rainy season, soil moisture that is constant, tropical temperatures, and partial shade for best growth. The plant is a climbing vine that grows up to 33 feet high. It needs a tree or pole for support. Sometimes pepper plants are interspersed in tea or coffee plantations. The pepper vine has broad, shiny dark green, heart-shaped leaves. New vines are propagated by stem cuttings from older vines. It takes 2 to 5 years for a plant to begin bearing fruit; they will produce peppercorns for up to 40 years. The peppercorns form in a cluster on a long spike, which looks like a cat's tail. The spike is a flower with a multitude blossoms. At first a spike has about 50 small blossoms, densely arranged on it. The blossoms gradually become small berrylike fruits, which we call "peppercorns." When the berries are fully mature, they are green; as they ripen further, they become yellowish red. Most of the berries are picked when they are dark green, just as they begin to turn yellow and red. They are then immersed in boiling water for about 10 minutes, which causes them to turn dark brown or black in an hour. After that they are spread out to dry in the sun for three or four days. Green peppercorns are the less than fully mature berries before they become dark green. In countries where pepper is grown, they are used fresh. They have an herbal aroma and flavor. For shipment elsewhere, they are either packed in brine or dried. The dried have more flavor than the brined, and can be easily reconstituted by soaking in warm water for a few minutes. Green peppercorns are very popular in Thai cooking. White peppercorns are obtained by processing completely ripe dark green, yellow, and red peppercorns. The outer coating, called the "pericarp," is removed, leaving the white seed beneath. This is accomplished by putting the peppercorns in a sack and submerging them in water for 7 to 15 days. The softened coating is removed by washing and rubbing, or by trampling, and the berries are then spread in the sun to dry. The sun turns the gray color a creamy white. The whitest pepper comes from corns that are soaked in running water, such as a stream or artesian spring. White pepper is used in dishes and sauces where black specks would diminish the beauty of the white appearance. It is also used when a lot of heat is needed. The word for "pepper" in ancient India means "poison killer." This is because pepper was used from early times as a food preservative. It killed bacteria and fungi. It also had a number of medicinal uses to treat ailments such as coughs and asthma, and was used to aid in digestion. Peppercorns contain about 3 percent essential oil, which has the aromatic flavor of pepper. The oil is distilled and used in meat sauces. The pungent or sharp flavor of peppercorns is not contained in the oil, but rather in four chemicals found primarily in the pericarp. The chemicals are peperine, chavicine, piperidine, and piperettine. They are classified as either lipids or alkaloids. Peperine and chavicine have the same molecular ingredients, but different structures. Both are pungent, but chavicine more so. When pepper is ground, chavicine gradually is transformed into peperine, resulting in a decrease of pungency. Pepper is not soluble in water, but does dissolve in alcohol. Because of that, pepper is best added last to water based dishes; too long a stay in water can turn pepper bitter. In alcohol dishes, the chemicals in pepper break up and result in a hotter taste. This is true of white pepper in particular. Asian cooks use white pepper in rice wine dishes to get plenty of heat. Peppercorns are generally labeled by their point of origin. Since peppercorns are native to the Malabar Coast of India, it is no wonder there are Malabar peppercorns. Malabar is the south west coast of India. It is the area now covered by the modern Indian state of Kerala. The Portuguese established ports there for trade during the age of exploration. Their main port was Cochin, the first European settlement in India. The English also established ports on the Malabar Coast. The first was named "Tellicherry," also spelled "Thalassery." It was the main port for exporting peppercorns, coffee, sandalwood, and coconuts. Both Malabar and Tellicherry peppercorns now come from the Malabar Coast of India. How are they different? As the peppercorns ripen on the vine, the ones that form towards the tip get bigger and ripen first. They get a bit red in color. The peppercorns closer to where the stem joins the vine ripen less and are smaller. They stay green. The larger riper peppercorns are now called "Tellicherry;" the smaller less ripe ones are called "Malabar." Both are immersed in water, the process that turns them black, but the Tellicherry may have a reddish hue, the Malabar a greenish hue. The pepper vine was spread from India and Sri Lanka to Indonesia and Malaysia, which became major producers of peppercorns. Sarawak peppercorns are grown in the northeast coast of the Island of Borneo. The middle and southern part of Borneo is in Indonesia; the northern part, where Sarawak is located, is a part of Malaysia. Lampong ("Lampung") peppercorns are grown in Indonesia, on the southeastern tip of the Island of Sumatra. Both Sarawak and Lampong peppercorns are picked and processed so as to be black. Muntok peppercorns are also grown in Indonesia. Muntok is the chief port located on the island of Bangka. Bangka is just off the south east coast of Sumatra, Indonesia, a bit north of Lampong. The peppercorns are processed to be white peppercorns. The peppercorn vine is now also cultivated in Brazil. It is one of the foremost suppliers of green peppercorns. The peppercorns from the different areas have slightly different taste and heat characteristics. I have found Sarawak and Lampong to be hotter than Malabar and Tellicherry, but less complex in flavor, less pungent. It is worth trying peppercorns from different sources; they vary like wines from the same grape variety grown in different regions. Dried green peppercorns can be reconstituted by soaking in water. They will then have an herbal flavor. Use them in sandwiches, salsas, and on salads. They can also be ground to season vegetables, rice, and polenta. http://www.cookswares.com/discussions/peppercorns.asp