The new tally, compiled by botanist Marcus A. Nadruz Coelho of the Rio de Janeiro Botanical Garden Research Institute and Cecília Cronemberger of the Chico Mendes Institute for Biodiversity Conservation, updates and expands every previous account of the park’s vegetation. The breakdown is remarkable in its breadth: 2,342 species of flowering plants, 433 ferns and lycophytes, 250 bryophytes, and a single gymnosperm. To put that figure in perspective, the park harbors roughly 38 percent of all plant species known to the entire state of Rio de Janeiro within an area representing only about half a percent of the state’s territory. The list has grown 26.7 percent since the most recent compilation in the park’s management plan, which recorded 2,268 species, and 34.4 percent since Carlos Rizzini published his pioneering Flora Organensis in 1954, which identified 2,029 species.

Reaching these numbers required years of patient fieldwork combined with an ambitious archival detective operation. Between 2007 and 2011, the researchers conducted systematic collections of fertile plant material across all vegetation types in the park, prioritizing zones flagged as poorly inventoried. They used the walking method, an expedited qualitative survey technique in which collectors traverse trails and terrain on foot, photographing and pressing specimens for deposition at the herbarium of the Rio de Janeiro Botanical Garden Research Institute. But fieldwork alone could not capture two centuries of accumulated knowledge. The team then combed through the Carlos Toledo Rizzini Reference Collection housed at the park headquarters, queried the national JABOT and SPECIESLINK online databases, and consulted dozens of international herbaria across Europe and the Americas, tracking down specimens gathered by naturalists as far back as the 1820s.

Those historical records tell their own story of scientific obsession. The oldest angiosperm collections in the park date to March 1823, when L. Riedel gathered Floscopa glabrata, followed by H. Beyrich’s 1828 collection of Ichnanthus nemoralis, a grass whose duplicate now resides in the United States National Herbarium as a copy of a specimen once held in Berlin. The oldest fern record, Adiantum cuneatum, was collected by Gaudichaud in 1831, while the earliest bryophyte specimens, Entosthodon bonplandii and Funaria hygrometrica, were gathered by George Gardner in 1836. Established in 1939 as Brazil’s third oldest national park, Serra dos Órgãos had already been visited decades earlier by legendary naturalists such as Spix and Martius, whose Flora Brasiliensis project helped lay the foundations of Brazilian botany.

What makes the park so extraordinarily diverse is its topography. The terrain is rugged and dramatic, with altitudes ranging from 80 meters to 2,275 meters at Pedra do Sino, the park’s highest summit. This vertical span generates a staircase of distinct vegetation zones: submontane forest on the lower slopes between 50 and 500 meters, montane forest on the plateaus between 500 and 1,500 meters, upper-montane forest above that, and finally the campos de altitude, open herbaceous-shrub formations that begin around 1,800 meters on the ocean-facing slopes and 1,600 meters on the inland side. About 37 percent of the park is upper-montane forest, 24 percent campos de altitude, 22 percent montane forest and 17 percent submontane forest. The climate amplifies this variety. Under the Köppen-Geiger system the region is classified as temperate oceanic, with no dry season and orographic rainfall that produces the highest precipitation in Rio de Janeiro state, exceeding 2,000 millimeters annually. Winter minimums can plunge to 1 degree Celsius and, at the highest elevations, down to minus 5 degrees, conditions more reminiscent of temperate mountains than tropical lowlands.

The campos de altitude, isolated like islands on the mountaintops, are evolutionary laboratories. Because these high-elevation habitats are cut off from one another, their flora and fauna have evolved in isolation, producing exceptional endemism. Previous research identified 23 threatened plant species in the park’s high-altitude grasslands, and a single valley was found to hold 347 plant species, 66 of them endemic to the formation and 13 exclusive to the park. The new inventory confirms this pattern across the whole protected area: 28 species are endemic to the park itself, including the aroid Anthurium cronembergerae, the bromeliad Tillandsia organensis, the melastome Bertolonia organensis, and two lycophytes and two bryophytes found nowhere else on Earth. Another 190 species are endemic to Rio de Janeiro state, meaning the park alone harbors 22.17 percent of the 884 species endemic to the state.

The dominant plant families mirror the broader signature of the Atlantic Forest. Orchidaceae leads with 285 species, followed by Asteraceae with 171, Melastomataceae with 158, Myrtaceae with 144, Rubiaceae with 115, and Bromeliaceae with 107, with Piperaceae, Dryopteridaceae, Polypodiaceae and Fabaceae rounding out the top ten. Together these ten families account for 34 percent of local diversity. The prominence of orchids, bromeliads and polypodiaceous ferns underscores the critical role of epiphytes, plants that live on other plants, in tropical rainforest ecosystems. The park also shelters 103 species classified in IUCN threat categories, including 20 angiosperms listed as Critically Endangered and one, the rubiaceous herb Hindsia violacea, considered Extinct. Tragically, the inventory suggests that extinction may not be permanent: renewed collection in rugged, rarely visited terrain could rediscover species believed lost, a phenomenon documented repeatedly in well-studied floras worldwide.

Yet the inventory also exposes a sobering truth about the limits of knowledge. A total of 1,195 species, nearly 38 percent of the park’s flora, are known from only a single collection record and are therefore considered locally rare, with 503 more known from just two records. The researchers attribute this to a combination of collection bias and the sheer habitat diversity generated by the altitudinal gradient. Accessibility bias, the tendency for scientific knowledge to concentrate near cities and along easy routes, shapes our understanding of species richness at every scale. Three of the five richest protected areas in Brazil, including Serra dos Órgãos, Itatiaia National Park and Tinguá Biological Reserve, lie in Rio de Janeiro state, historically the main gateway for European naturalists, while remote Amazonian parks such as Serra da Neblina, with 1,047 recorded species, remain comparatively unexplored. Even within the park, certain rugged areas remain undersampled, a pattern echoed in mammal surveys of the same landscape.

The consequences of this work extend well beyond taxonomy. By identifying which species are rare, endemic or threatened, the inventory provides a scientific foundation for conservation planning, reforestation efforts and the possible establishment of additional protected areas in the Serra do Mar corridor, which protects more than 800,000 hectares of Atlantic Forest across São Paulo, Rio de Janeiro and Paraná states. The Atlantic Forest has lost roughly 76 percent of its original cover, and in Rio de Janeiro state only 18.7 percent of forest remains, much of it in small, unprotected fragments. Against that backdrop, a single park holding 48 percent of the state’s known fern species and 16 percent of its angiosperm diversity is nothing short of extraordinary. The authors argue that encouraging further research and botanical collection could raise the representation of locally rare species, recover supposedly extinct plants, and reveal species entirely new to science, proving that even a forest two centuries in the study still guards secrets worth climbing mountains to find.

Subject of Research: Floristic inventory and conservation of native vascular plants and bryophytes in Serra dos Órgãos National Park, Atlantic Forest, Brazil

Article Title: Updated list of native flora of Serra dos Órgãos National Park, Rio de Janeiro state, Brazil

Article References: Nadruz Coelho, M. A., & Cronemberger, C. (2025). Updated list of native flora of Serra dos Órgãos National Park, Rio de Janeiro state, Brazil. Discover Conservation, 2(1), Article 38. https://doi.org/10.1007/s44353-025-00052-0

Image Credits: AI Generated

DOI: 10.1007/s44353-025-00052-0

Keywords: Atlantic Forest, biodiversity, botany, Serra dos Órgãos National Park, endemic species, floristic inventory, campos de altitude, conservation, orchids, ferns, bryophytes, Rio de Janeiro