BOTANY

OPUNTIA FICUS-INDICA

By CARLA DE AGOSTINI
 

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Opuntia ficus-indica, better known as prickly pear, is a succulent plant, with thick and fleshy leaves, belonging to the family of Cactaceae and it is xerophilous, that is living preferably in arid environments, where it can also reach 5 meters of height. The plant does not have a main trunk, its stems are cladodes, commonly known as paddles, which take care of photosynthesis, whereas its leaves with time have evolved into thorns. Its great ability to adapt in unfavorable environments is also due to its unique photosynthesis that limits water loss. This photosynthetic pathway, called Crassulaceae Acid Metabolism or CAM, separates the processes of assimilation and fixation of CO2 over time. CAM plants, in fact, open their stomata at night and not during the day to absorb carbon dioxide. This happens because at night temperatures are lower and the plant loses less water than it would during the day, when it closes its stomata and converts energy into simple sugars. This type of photosynthesis increases the ability of succulent plants to maintain water balance, which is why most CAM plants occupy arid or saline environments, and in general all those in which water availability is periodically low.

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The origin of the epithet Opuntia ficus-indica has been debated: according to someone it derives from an ancient region of Greece, Locris Opuntia and from its capital city Opunte, near which the writings of Pliny the Elder reported about a plant with tasty fruits rooting from the branches. With time, however it has been confirmed the plant is native to Mexico and the botanical name is therefore due to the morphological similarity of its fruit with the Mediterranean fig and to its geographical origin, West Indies. According to a legend, at the time of Spanish conquerors, the emperor of Aztecs, Montezuma, used to receive as tribute from the subjugated states sacks full of grain. That is a cochineal (Dactylopius coccus) parasite of the cladodes of prickly pear, from whose dried body it is possible to extract the dye of carmine red, useful for dyeing ceramics, fabrics and architectures, of a tonality so intense never seen before. Its coloring power is in fact ten times stronger and more persistent than kermes, considered until then the best product for red dyeing, so much so that the Spaniards decided to keep the process hidden for almost two and a half centuries, creating a monopoly of cochineals grain, which became among the most demanded goods. Among the biggest buyers there were the English who particularly cared about the color of their uniforms, the famous red coats. Until 1777 finally a French doctor was able to discover the process. Once obtained the information the English exported to Australia the plant and its cochineals, in the hope of making plantations to make the grain, but despite the apparently perfect climate, the insects did not survive. On the contrary, prickly pears became infesting plants damaging pastures and territory: it is estimated that in 1920 they were spread on more than 30 million hectares, with a rate of conquest of half a million hectares per year! An enormous damage which still today is trying to be remedied by looking for solutions.

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In Europe the plant was introduced for the its fascination and in the sixteenth century it became an important protagonist of botanical gardens, both for reasons of scientific curiosity and for its ornamental vocation. Success was also confirmed by the frequency with which the plant is represented in drawings or figurative arts, such as the Fountain of the Four Rivers in Piazza Navona, where Bernini put Opuntia in the background of the representation of the Rio de la Plata.

Throughout the Mediterranean basin, its ability to adapt and propagate has facilitated its reproduction, especially on the Italian islands, where the prickly pear has acclimatized to become a characteristic feature of the landscape and is often used as a windbreak or fence for flocks. It has also proved to be an inexhaustible source of products and functions. The plant was immediately appreciated for the forage use of its cladodes and for its fruit, which can be eaten fresh or used to make juices, liqueurs, jellies, jams, sweeteners and much more. In Mexico, the young cladodes, known as nopalitos, are also eaten and used as fresh vegetables. Sicily has historically had the widest range of uses. It is in fact grown in inland areas, where the fruit is even called the 'bread of the poor', and in coastal areas, tending to be grown in fruit gardens for productive use and pleasure. The Sicilian peasant tradition is rich in prickly pear products, from its liqueur to mostaccioli (typical biscuits) and mustard. In 1891, René Bazin, a French writer of the late 19th century, wrote that "with twenty or so prickly pears... a Sicilian finds a way to have breakfast, lunch, dinner and sing in the interval".

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And it is from the Sicilian, and in part Sardinian, shovels that the prickly pear arrives and invades Eritrea, planted both by 19th century Italian missionaries and by migrants of the first Italian colonization. Here, the beles, the name in Eritrean, are not only the fruit but also the nickname jokingly given by peers from the Horn of Africa to second-generation Eritreans living in Italy, because they arrive with the same punctuality as the fruit: in the summer rainy season, and then leave again.Today, Opuntia ficus-indica is used for a wide variety of products, both for its high nutritional value, rich in minerals, especially calcium, phosphorus and vitamin C, and for its mucilage, the substance that allows the plant to have water reserves. Thanks to this, the prickly pear has become a major player in eco-sustainable innovations. For example, a Mexican professor of chemical engineering, Sandra Pascoe Ortiz, has patented a plastic and biodegradable material: by mixing prickly pear juice with glycerin, proteins and natural waxes, she has obtained a liquid which, after being laminated and dried, becomes a completely non-toxic, biodegradable and edible bioplastic. In Italy, too, alternative uses of prickly pears are proliferating. For example, a glue for fresco restoration work has been experimented with using mucilage, and a textile industry has obtained cruelty-free eco-leather from its waste. But that's not all, there are also sunglasses made from their fibers, furniture and sculptural lamps made from the waste from shovels that are entirely biodegradable at the end of their life!

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Photo ©CRISTINA ARCHINTO