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

An update was made on the vascular and bryological flora of the Serra dos Órgãos National Park, located in the Atlantic Forest domain, Rio de Janeiro state, Brazil. Collections of plant samples were carried out from 2007 to 2011. These data were complemented by consultations with national and international herbaria, and scientific publications related to the flora of the Park. The total number of known plants is 3026, divided into 2342 angiosperms, 1 gymnosperm, 433 ferns and lycophytes and 250 bryophytes. Of these, 28 are endemic to the Park, 190 are endemic to the state of Rio de Janeiro, and 102 are classified in one of the IUCN threat categories. With these results, Serra dos Órgãos National Park becomes the Brazilian protected area with the richest known flora, harboring 38% of the species known to Rio de Janeiro state in an area of about 0.5% of its size. Despite the park’s great plant diversity, about 38% of the species had only one record and may be considered locally rare. Encouraging research and botanical collection in the park may increase the representation of locally rare species, rediscover species which are considered extinct and record new species for science.