Last January, Alessandro Rapini and his team from the State University of Feira de Santana (UEFS), State of Bahia, went to the town of Santana do Riacho in the Serra do Cipó mountain range, State of Minas Gerais. There, they came across some 15-centimeter tall plants with pinkish flowers growing in the midst of the grassy fields. They were Hemipogon abietoides that had not been seen since 1825, when naturalists who were part of the Langsdorff exploration team had traveled along this road – currently off limits to vehicles – to the town of Diamantina. In this same region, the botanists also came across a kind of shrub with cream-colored flowers, the Minaria hemipogonoides, thought to have become extinct some years ago. The two recently rediscovered species are part of the broadest survey on unknown plants in Brazil, described in the book Plantas raras do Brasil [Rare Brazilian Plants] (published by Conservation International and by the State University of Feira de Santana, 496 pages).
The survey involved 170 experts from 55 Brazilian and foreign research institutions and describes 2,291 species confined to areas of up to 10 thousand square kilometers (equivalent to a square of 100 kilometers on each side). Most of these species, however, are limited to even smaller areas and some species are only found in a single place as, for example, a plant from the bamboo family. This 30-centimeter tall species, the Melica riograndensis, only grows in the municipal region of Uruguaiana, State of Rio Grande do Sul, while the Cissus pinnatifolia, a red-flowered vine, only grows in the forests that lie near the coast, in the region of Santo Amaro das Brotas, State of Sergipe. Many of these species are quite peculiar, such as a cactus plant with a blue-stemmed flower that resembles a cross between a rose and an orchid.
Some regions with specific climate and soil conditions are full of rare species. This is the case of the region around Datas, in the Diamantina plateau, north of the city of Belo Horizonte, with approximately 90 species, and the entire Serra do Cipó mountain region, also in the State of Minas Gerais, which has double the number of species. The State of Minas Gerais has the highest number of rare plant species: 550. Minas is followed by the State of Bahia, with 484 species, Rio de Janeiro with 250 species, Goiás (including the country’s capital) with 202 species, Amazonas with 164, Espírito Santo with 135 and São Paulo with 123. The rare plants are more commonly found in the highlands, such as the rupestrine fields – open vegetation that grows on rocky or stony terrain – in the Cadeia do Espinhaço region in the States of Minas and Bahia, and the Chapada dos Veadeiros, in the State of Goiás. This vegetation also grows in the humid rain forests of the central Amazon Region and in the Mata Atlântica rain forest, which extends from the south of the State of Bahia to the State of Paraná, crossing the mountain ranges of the States of Espírito Santo, Rio de Janeiro and São Paulo.
Among sugarcane plantations
There is another explanation for the abundance of rare plants in the aforementioned regions. In addition to suitable climate and soil, these areas have been extensively studied by botanists because they have an abundance of native species or lie close to cities. The forests in the Petrópolis mountain range, for example, have been visited by naturalists since the times of Emperor Dom Pedro II. These forests are the habitat of at least 52 species that are probably only found there. Some regions, such as the area of Altinópolis, which is surrounded by sugar cane plantations and industries that lie around the city of Ribeirao Preto, State of São Paulo, are a natural refuge for rare species. This is the region where the Xyris longifolia is found, rediscovered after more than one century. These plants sometimes go unseen even in accessible regions. “Only experts are able to recognize them as rare species and this recognition is not always immediate,” says Rapini, one of the publishers of the book, edited by Ana Maria Giulietti, former director of research at UEFS, and by José Maria Cardoso da Silva, science vice-president of Conservation International in Brazil.
Being rare implies fragility; hence, many of the species listed in the book are endangered species and some of them may have actually disappeared. “I wonder if the Anathallis guarujaensis still exists,” says Fábio de Barros, a researcher at the São Paulo Botany Institute. This species – a three-centimeter tall orchid with six-millimeter flowers – was last seen in 1938 in the forests – now urbanized – surrounding the town of Guarujá on the island of Santo Amaro. It was spotted at that time by Frederico Carlos Hoehne, the founder of São Paulo’s Botanical Garden. The orchids form a group (or family) that, in Brazil, comprises some 2,600 species, of which 1,800 are only found in specific environments of the Mata Atlântica rain forest. Barros was part of a group of experts that identified 72 rare orchid species in Brazil. Most of these are small, but there are some larger ones, such as the Adamantinia miltonioides, with pinkish flowers, found as recently as 2004, at an altitude of 1,300 meters in the region of Mucugê, State of Bahia. The 20-centimeter tall Grobya cipoensis with five-centimeter yellow flowers, a rare species found in the Serra do Cipó mountain range, was only identified five years ago. This species was found living under a huge canela-de-ema, the Vellozia gigantea tree, in a region of the Serra do Cipó. “We have described new species in the 21st century,” says Barros. “This is a sign that we still have much to learn about our native flora, even the large groups, such as orchids.”
Rapini started to believe that rare plants might be genetically related to each other after he had identified groups of rare species – rather than isolated rare species. “These groups evolved in relatively small areas and, upon diversifying, generated rare, closely related species.” Of the roughly 20 species of Minaria, of the Apocinaceae family, regarding which the team from UEFS is conducting genetic studies, more than half are found in isolated regions in the Cadeia do Espinhaço region. In another family, the Melastomataceae, most of the 35 species of the Marcetia genus are found only in the Chapada Diamantina region. However, it is sometimes impossible to establish these evolutionary affinities. The genetic material of the two Paepalanthus species, which live for just one year, normally used in this kind of study, was insufficient to define the kinship ties.
Botanists want to know exactly why in regions such as the fields of the Cadeia do Espinhaço more species are concentrated than in other areas. In search of explanations, Luciano Paganucci de Queiroz, a professor at UEFS and one of the coordinators of the book, along with researchers from three other universities in Bahia, conducted a genetic comparison of eight groups of plants with various species exclusive to the Cadeia do Espinhaço region, including orchids, cactuses and trees. The preliminary results indicate that the older lineages began to appear 20 million years ago – and the more recent lineages appeared 4.5 million years ago, when specific groups of grasses also started to diversify in the Cerrado region. The botanists concluded that the non-continuity of the mountain regions and the mosaic-like environments possibly produced the geographic isolation of plant populations, thus leading to the diversification of some groups.
At the initiative of Cardoso, from Conservation International in Brazil, who published an exploratory study on the conservation of birds and plants in the Cerrado region, and under the scientific leadership of Ana Maria Giulietti, the botanists created a task force and focused on finding species restricted to and distributed throughout specific geographical regions, based on existing field studies. After all the species had been listed, some team members applied the geographical coordinates where each species had been found to a map of hydrographical micro-basins. This resulted in 752 key areas for biodiversity, thus named because they have at least one rare plant species. Together, these regions totaled 140 million hectares (1 hectare equals 10 thousand square meters).The smallest region consists of 327 hectares on the island of Almas, in the town of Parati, State of Rio de Janeiro. This region is the exclusive habitat of the Aureliana darcyi, a 3-meter tall shrub that grows near the coast; the biggest region consists of 2.5 million hectares, and lies near the Iça River, a tributary of the Solimões River, State of Amazonas.
Cardoso believes that the 752 areas should be included in the federal government’s environmental conservation plans. Other spheres of government and groups should also take action in this respect. “In many cases,” he says, “the local governments have to take the initiative, because many species are restricted to municipal regions.” The survey and the maps can be used as an argument to prevent the construction of gated communities and other property developments on lands where these rare plants are found. “The existence of rare plants is one of the items that justify an embargo for a request to deforest an area,” says Barros.
“We were able to mobilize the scientific community,” says Queiroz. The book, with a brief description of the plants, grouped into 108 families, and the maps, with the key areas for the conservation of biodiversity, are available at www.plantasraras.com.br. The site also has room for messages, which has attracted a lot of interest. “More botanists have already offered to contribute information on other groups of rare plants,” says Queiroz.Republish