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Botany

The Beauty and the beast

A study reveals orchids from Central Brazil and describes the damage caused by viruses and insects

Among the 16,000 orchids grown at the Botanic Institute of Sao Paulo, united within long covered corridors of plants, stacked up to the roof, there has been lost for around twenty years the chuva-de-ouro (golden rain), thus named in virtue of its small yellow flowers that fall from its offshoots lie a waterfall. This species, the Oncidium flexuosum, is relatively common in Brazil but has the value of a rare jewel for the botanist Fábio de Barros: it was indeed an example of a chuva-de-ouro that aroused in him a passion for orchids some thirty-two years ago. At that time, as a sixteen year old, Barros did what today would be disapproved of: he pulled off a plant from a tree in a country estate in Juquitiba, in the southeast of the state of Sao Paulo, and took it home to the city of Sao Paulo. It was his mother, Antonieta, who explained to him that he was dealing with an orchid. “This is one of the best memories that I have of my mother”, he says. Nia, as she was known, died a few months after this incident and did not have time to see her son turn himself into one of the principal authorities on orchids in the country.

Barros became so respected that his name has been given by his colleagues to an orchid with purple flowers, called Pleurothallis fabiobarrosii, which lives in the stony soil of a group of mountains in the north of Minas Gerais State known as the Espinhaço ridge. It also grows in the rustic countryside of the same state, brimming with herbs and shrubs with many colored flowers, a variety of orchid recently described by him: the Grobya cipoensis, which perfumes and decorates the highest stretches of the Cipó ridge, in the central region of Minas Gerais, with its sweet aroma of honey and tiny yellow flowers speckled with brown.  The G. cipoensis, the latest of the eleven species described by Dr. Barros, was presented in May of 2004 in an article published in the British magazine The Botanical Journal of the Linnean Society. In this same piece of work, Barros and the botanic illustrator Ricardo de Azevedo Lourenço described other species of the same genre, the Grobya guieselli, whose yellow flowers resemble a bird. Found only in stretches of the Atlantic Rainforest in the state of Santa Catarina, the G. guieselli can grow up to three times larger than the species from the Cipó ridge and can attain a height of 61 centimeters.

Other Barros discoveries appear in the book Orquidologia sul-americana: uma compilação científica [South American Orchidology: a scientific compilation], coordinated by him and Gilberto Kerbauy, another specialist in these plants, who works at the Biosciences Institute of the University of Sao Paulo (USP). Published by the Secretary of the Environment for the State of Sao Paulo, the work brings together studies of pure scientific stamp and others essentially practical, signed for by twenty Brazilian and one Argentinean researchers’ enriched, clearly, with photographs and dazzling illustrations.

A study by Barros himself concerning the distribution of orchid species in the plateaus and ridges s of Central Brazil merits highlighting. On analyzing the hills of the states of Minas, Goiás and Bahia, the Paulista botanist verified the surprising diversity of orchids of this region. It had been believed that this area in the heartland of the country was poor in species of this group of plants since it was occupied by the Cerrado, a type of vegetation that is normally dry, with stunted and sparse trees, subject to frequent natural fires.

The flowers of the rustic countryside
By comparing the vegetation of the Cipó ridge, in Minas Gerais , with that of Cardoso Island, a left-over of the Atlantic Rainforest off the southern coast of the State of Sao Paulo,  Barros knocked flat this erroneous idea. In fact the Cerrado as a whole really shows low diversity of orchids in the face of the exuberance in the Atlantic Rainforest or the Amazon basin. But two specific environments of the Cerrado – the rustic countryside, which occupy the highest stretches of the Cerrado, above 1,000 meters in altitude, and the riverside ciliates, which thrive on the edges of rivers – house dozens of different species. Therein live examples as distinct as the Habenaria magniscutata, an earthy species with roots and fine leaves, and the Bulbophyllum weddellii, with roots and fleshy like leaves – both excluded from the rustic countryside.

Finally, the diversity of the orchids of the Cerrado region shows itself to be only a little inferior to that observed on Cardoso Island, a protected area of the coastal forest that makes up the orchids’ paradise: only there, in an area close to 150 km2, one hundred and one (101) species have already been identified. This total represents close to 3% of the 3,000 orchid species existing in the forests and in the countryside of Brazil, a country rich in exclusive species: close to 1,700 only exist here. In the whole world there are some 20,000 natural species and a further 30,000 hybrids, generated by crossing different species in the laboratory.

How can one explain this unexpected richness of Central Brazil? Part of the answer appears not to be there, but to be in the two neighboring ecosystems: the Amazon Rainforest in the north and northeast and the Atlantic Rainforest in the east. “These two major masses of forest preserve a wide variety of species of orchids that can also be found in the riverbank vegetation of Central Brazil”, explains Barros. To a certain extent, the riverside vegetations of the Cerrado connect this environment with their more humid neighbors, the Amazon and the Atlantic Rainforest, allowing for an exchange of species.

A lot more difficult is to explain what makes these plants so fascinating. The reasons couldl be as varied as the very orchids themselves. There are species of 2 millimeters, others of 4 meters in height; their flowers can be absolutely white or as colored as the canvases of surrealist artists; some species generate a single flower, whilst others exhibit more than one hundred of them at a single time. Their strategies for survival are also notable: these plants adapt themselves to practically any environment – the majority are epiphyte, or that is to say, grow upon trees – and they can go for months without rain because they are capable of storing water and nutrients in their leaves, in their roots and in the stock.

The smell of rotting meat
But what is even more enchanting with these plants are the various reproduction mechanisms. At a certain point, the English naturalist Charles Darwin, the creator of the evolution theory of species through natural selection, wrote that the adaptations linked to the pollination of orchids transcribed even what the human imagination could create. Examples of some species of Ophris imitate the sexual partner of the pollinating insects, which, seduced by the smell, color and form, attempt to copulate with the flowers – clearly it does not work out but they leave there with pollen that they carry to another orchid flower. Others attract the insects by way of the form of their flowers, whilst others, such as the genres Pleurothallis and Bulbophyllum, would make anyone turn up their nose with a smell of rotting meat, but it is exactly this smell, liberated by its purplish flowers, that attract the flies – and it is they who carry the pollen to another example of the same species and thus guarantee the plant?s fertilization.

Virus and wasps
In another chapter of the book,  Lo Siok Tien, Silvia Galleti and Cesar Chagas, from the Botanical Institute of Sao Paulo, show how they deal with the main viruses that infest these plants. Of the twenty-seven (27) already identified, there are three that are more aggressive: the virus of cymbidium mosaic virus disease of Cymbidium, the necrotic rings/flecks of Odontoglossum and Rhabdovirus. The first named virus affects 11% of the orchids in the state of Sao Paulo and tinges its leaves with yellowish markings. The virus Odontoglossum brings about rings on the dead tissue, whilst that of Rhabdovirus speckles the leaves with reddish-brown points. Principally transmitted by the use of contaminated scissors or pots, these viruses are only contained by means of the disinfecting of the material for potting and planting or more radical measures such as the elimination of the sick or suspect plants that have been infected.

Viruses are not the only natural enemies of orchids. A small black wasp, the Calorileya nigra, deposits its eggs in the roots of some species of the genre of Cattleya, which, as a consequence, grow ugly and deformed. As soon as the larvae of this wasp develop, little beads technically known as root like branches grow on the roots. They are described in detail in a chapter signed for by Dr. Barros and two specialists from the Biosciences Institute of USP, Drs. Jane Kraus and Makoto Tanoue. There are also other chapters with interesting studies on orchid producers, whose sales have an annual gross income of around R$ 400,000.00 on the internal market, whilst exports of orchid offshoots generates an annual income of around US$ 100,000.00. It makes up a small portion of the flower market in Brazil, estimated, in this same book, at R$ 2 billion, but this business still has room for growth. “There is immense potential to be explored”, emphasizes Barros. “Brazil has a vast territory, a climate suitable for the cultivation of tropical plants and an elevated variety of species that could be grown commercially.”

The Brazilian flora in fact houses a vast variety of orchids, many of them as yet undiscovered and others probably already extinct – only in the State of Sao Paulo there are around one hundred and forty (140) species that run the risk of disappearing. In Brazil two of the most threatened orchids are the Cattleya schilleriana and the Cattleya velutina, widely collected as they produce large and eye-catching flowers – both practically no longer exist in their natural environment, the Atlantic Rainforest, and are maintained only in greenhouses. But there are ways of redeeming the loses: groups of orchid lovers are reproducing rare native species in the laboratory and even re-introducing these plants into their natural environment. This is a symbolic form of devolving back to nature what man has removed.

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