Pineapple

The Pineapple is a species of flowering plants that produces tropical fruit which is sold around the world and has long been prized for its sweet, delicious flavor and unique appearance. Although once considered a delicacy only available to kings, pineapples are now one of the most popular tropical fruits and are grown all over the world.

They are unique in being the only edible members of the Bromeliads, and also the "fruit" is actually a collection of one hundred or more individual fruits fused together. It's name is derived from the Spanish name "piña", meaning pine cone, and the Indian name "anana", meaning excellent fruit.

Anatomy
Pineapples are herbaceous, terrestrial members of the Bromeliad family. The plant is typically two to five feet high with a short stem. The leaves are large, at one to three feet in length, and grow from the soil at the base of the stem. The leaves have a waxy coating and have needles or spines on the tips. These leaves grow in a circular pattern called a rosette, and they may be green in color or have red, yellow, or white stripes. Pineapples have simple leaves with spiny margins and parallel leaf venation, which is typical of monocot plants. Pineapple leaves allow the plants to survive periods of drought better than other tropical plants. The leaves form around the stem in an overlapping spiral, and water collects in the "bowl" formed by the overlapping leaves to be absorbed later. In addition, the thick cuticle prevents water loss, as does the use of the CAM pathway to fix carbon dioxide for photosynthesis, which only requires that the stomata of the leaves be open at night, rather than during the day as well.

Pineapples have adventitious roots that grow from the base of the stem, as well as some aerial roots. The adventitious roots extend into the soil and grow up to 2 meters long and 85 cm deep, but their growth may be restricted if the pineapple is not cultivated in proper soil. Aerial roots grow between leaves on the stem and wrap around the stem, allowing additional moisture to be absorbed.

In summer, when the plant is ready to bloom, the stem grows longer and the tip enlarges. Flowers with red or purple petals grow from the stem's apex, accompanied by yellow, red, or green bracts (scale-like modified leaves). A cluster of smaller leaves also develops atop the flower cluster. If the flowers are to produce seeds, they must be fertilized by a pollinator (usually a hummingbird), because pineapples are incapable of self-fertilization. Most pineapples grown commercially have undeveloped seeds or lack them altogether. Pineapple growers do not grow their crops from seeds and take measures to discourage pollination as it is not necessary for the fruit to develop. Flowers remain on the plant for about two weeks, with the flowers nearest the base being the first to open.

After flowering, it takes an additional six months for the fruit to fully develop, and only one fruit is produced per year. The pineapple fruit, called a syncarp, is actually over 100 developed ovaries fused together, each one from a separate flower. The oval-shaped fruit may grow to a foot in length and weigh ten pounds or more at maturity. The sweet, juicy interior of the fruit is edible and ranges in color from white to yellow. The stem of the plant becomes the core of the fruit and is much tougher and more fibrous than the rest of the fruit. The syncarp also has a thick, waxy rind made up of hexagon-shaped eyes that turn dark green, yellow, yellow-orange, or red when the fruit ripens. Each eye is located on a separate ovary in the fused compound fruit.

The pineapple puts forth shoots from the base of the fruit, leaves, or stem. Shoots from the base of the fruit are called slips, those growing from the axils (base of the leaves) are suckers, and the underground shoots from the stem base are ratoons. These shoots are all capable of growing into new plants.

Reproduction
Pineapples use vegetative growth to reproduce through four different methods: slips, suckers, crowns, and ratoons. Slips are shoots that grow from the stem at the base of the fruit. Suckers grow from the leaf axils (bases). Crowns come from the top of the fruit, and ratoons are root-like shoots that grow from the stem beneath the soil. All of these forms of vegetative growth, called propagules, may be removed from the parent plant and used to propagate new pineapple plants. This is the primary method of propagation used by commercial pineapple growers. Slips and suckers are used more often for commercial growing, but the crown of a store bought pineapple can be used to grow a pineapple plant at home.

After removing the propagule from the parent plant, the propagule should be allowed to dry and cure for one to two weeks to allow roots to develop before planting, and it should be kept warm while it is being cured. The crown can be placed in water to cause the roots to develop. After this, the propagule can be placed in the ground or cultivated in a pot. Pineapples prefer soil that is slightly acidic (pH of 4.5 to 6.5), sandy, and has good drainage. They should be grown in full sun for the best fruit, and proper amounts of nitrogen are necessary, which can be supplied through a fertilizer. Potassium is also important, and the addition of magnesium has been shown to increase size and weight of the fruit. A pineapple grown from a propagule will produce its first fruit 12 to 22 months (about 1 to 2 years) after planting. The length of time required for a fruit to develop depends on a number of factors including temperature and the size and type of propagule used. A larger propagule will generally bear larger fruits in less time. Only one fruit is produced per year, and the best fruits are obtained in the first 3 to 5 years of fruiting, after which a new plant should be grown.

Pineapples may also reproduce sexually from seeds, although this method is often less successful than growing them from propagules and is not possible with store bought pineapples because commercial growers breed pineapples without seeds. Seeds may be allowed to germinate naturally or can be chemically treated with sulfuric acid to bring about quicker germination. Since pineapples are self-incompatible (unable to self-fertilize), they will only develop seeds if they are cross-pollinated with another pineapple plant. Their primary pollinators are hummingbirds, which have been banned in Hawaii, one of the chief pineapple-growing areas. In addition, pineapple fields often contain row after row of identical plants grown from propagules that cannot cross-pollinate because they are genetically the same. If a pineapple were to be cross-pollinated and develop seeds, there would be hundreds of tiny brown seeds in a single syncarp, with one seed for each individual fruit in the fused pineapple.

A unique feature of pineapples is that the fruit does not continue to ripen after it has been picked. This is because the fruit does not have a starch reserve that would allow the fruit to ripen any further. However, if any yellow-orange color is showing at the bottom of the pineapple, it means that sugar has begun to develop and the pineapple will taste sweet. Due to quick methods of shipping now available, such as air shipping, pineapples can reach their destinations as soon as three days after being picked, allowing them to be harvested ripe without spoiling in transport. A pineapple may be ripe even if it is still mostly green as long as the bottom has begun to change color.

Flowering can be forced to obtain fruit sooner than it would naturally develop. This is useful to pineapple growers as pineapples do not always flower regularly, especially in unfavorable conditions. Treatments containing ethylene, acetylene, or calcium carbide solution sprayed on the plant will cause flowering, and fruit can be harvested about six months after forcing. Placing pieces of apple in with the plant can also force flowering because apples give off ethylene gas. Hormone and chemical sprays can be used to achieve uniform fruiting in a large field so all of the crop can be harvested at the same time. Forcing may result in inferior fruit on weaker plants, but the plants can be treated to produce larger, heavier fruits using hormone treatments. Typically, hormone and chemical treatments are sprayed on the leaves to collect in the tight spiral "bowl" along with water and be absorbed by the plant.

Ecology
Pineapples are tropical plants that can grow in most warm climates where the temperature stays between 65 and 95 degrees Fahrenheit. Pineapples are easily harmed by frost. Temperatures should not fall below 60 degrees for very long, and temperatures of around 28 degrees cause serious damage to the leaves and result in a more acidic fruit if the plant survives. Pineapples should be grown in full sun for the best fruit, or in partial sun for ornamental purposes.

Soil should be sandy and loamy with good drainage as pineapple roots cannot grow well in hard soil. The soil needs to be mildly acidic, with a pH of 4.5 to 6.5. Pineapples should be watered regularly to ensure quality fruit production, but they can be harmed if too much water accumulates in the soil due to poor drainage. Because of their stomata and use of the CAM pathway for photosynthesis, pineapples withstand droughts very well for a tropical plant.

Pineapples are native to South America, but have since been introduced into warm climates all over the world because of their sweet, desirable fruit. They are believed to have been grown first by the Guarani Indians in Brazil and Paraguay. The Guarani Indians took pineapples on their sea voyages to places such as the Caribbean Islands, where Christopher Columbus encountered them in 1493. Columbus introduced the pineapple to Europe, where it was grown in greenhouses. It became a favorite fruit of kings and the wealthy, but as it was cultivated in more tropical areas around the world, it became increasingly available. Today, pineapples are grown in Hawaii, Puerto Rico, Malaysia, and Brazil, as well as China, Florida, Thailand, the Philippines, India, Nigeria, Costa Rica, Mexico, and most other tropical countries. Hawaii is currently the largest producer of commercially grown pineapples. Most pineapples grown are canned, but many are also sold fresh or as juice, and the fibers of the leaves are used in many countries as well.

Humans are the primary consumers of pineapples. Hummingbirds, as well as bats, are pollinators for pineapples. The plants are also susceptible to numerous insects and parasites. Common pests include nematodes, mealybugs, pineapple red scales, palmetto beetles, pineapple mites, sap beetles, moth and butterfly larvae, and cutworms. Crows, rats, rabbits, and mice may also cause damage by consuming the stems, stalks, and leaves.

Uses
Pineapples have long been prized for their sweet, juicy yellow fruit. Pineapple can be eaten fresh, but most commercially grown pineapple is canned to be sold. After the pineapple has been sliced for canning, fruit still remains on the core and rind. This is cut into cubes or chunks and sold. The parts left over are pressed for pineapple juice, which is popular as beverage. The pulp remaining after juicing, called pineapple bran, is used in animal feeds because of its high content of vitamin-C and vitamin-A. Pineapple is used widely in cooking paired with all kinds of meats and other fruits, and it is made into marmalade and preserves, juices, syrups, and candies. Pineapple is good eaten fresh or canned but should not be frozen because the cold causes the fruit tissues to break down and negatively affects the flavor. Fresh pineapple should not be used in gelatins because pineapples have an enzyme that will break down the protein in the gelatin (the heat caused by the canning process destroys this enzyme).

Pineapples contain the protein-digesting enzyme bromelain. For this reason, pineapple can help with digestive problems. It is used to chill-proof beer, tenderize meat, manufacture cereals, and tan leather. Bromelain is used medically as an anti-inflammatory agent and may be able to be used to break down blood clots, aid in cancer treatment, and stimulate kidney function. Pineapple is used as a remedy for corns, tumors, warts, sprains, ulcerations, sore throats, intestinal disorders, and constipation. In folk medicine, it was used to treat scurvy, bladder problems, scarlet fever, hypochondria, and jaundice. Fiber taken from the leaves is used to make thread for textiles, nets, clothing, jewelry, and other cloth products.

Pineapple has many vitamins and other health benefits that make it a very nutritious fruit. It contains large concentrations of vitamin-C and has high sugar and water content, making it both very sweet and very filling. It also contains vitamin B6, thiamin, manganese, copper, calcium, zinc, iron, potassium, magnesium, and phosphorus. It is a good source of fiber, and it has very little cholesterol, saturated fat, and sodium.

Pineapple does have some negative attributes as well. The leaves and fruit have spines that can cut people. Workers harvesting pineapple have to wear gloves to protect their hands, because the bromelain is strong enough to wear away their fingerprints. When consumed unripe, the fruit acts as a strong purgative and is considered toxic. Also, eating too many pineapple cores may cause fiber balls called bezoars in the digestive tract

Pineapples have also been used as decoration in homes, carvings, table and kitchenwares, and other areas. In the past, they were considered a luxury due to their high cost. Families who could afford to feed pineapple to guests were considered wealthy and generous, and the pineapple became a symbol of hospitality and friendship. Pineapples were found carved onto doors, fences, and gate posts to welcome guests into the home.

Varieties
While there are hundreds of varieties of pineapples grown in tropical countries all over the world, there are four varieties most often encountered. These are Cayenne (Smooth Cayenne), Spanish (Red Spanish), Sugarloaf, and Queen.

Smooth Cayenne pineapples are the variety grown in Hawaii and do well in canning and shipping. They are popular with pineapple growers because they do not have spines on their leaves. They have yellow flesh, are both sugary and acidic, and weigh 5 to 6 pounds.

Red Spanish are the other most common variety, slightly less popular than Smooth Cayenne. They have pale yellow flesh, high acidity, are somewhat square-shaped, weigh 2 to 4 pounds, and are usually canned or eaten fresh.

Sugarloaf pineapples are large (5 to 6 pounds) but don't ship well and need to be eaten fresh. Their whitish-yellow flesh is high in sugar and very sweet.

The Queen variety is a dwarf variety (2 to 3 pounds) with rich yellow flesh that is eaten fresh. The cores of this variety are not as fibrous as other varieties and can be eaten.

Other varieties include Pernambuco, which has a very sweet, pale yellow flesh; Abacaxi, which grows in tropical America; Monte Lirio, with smooth leaves and white flesh; and the Gold pineapple, a new sweet variety with high vitamin-C content developed by Del Monte in Hawaii.

Note: There is a wild pineapple (also called the red or variegated red pineapple) related to the commercial pineapple that belongs to the species Ananas bracteatus. The wild pineapple, native to Brazil, is edible and has dangerous spines sharper than those found on commercial pineapples.