The plant, which can grow up to one-and-a-half metres in length, was identified by scientists as a new species, and has since been named 'drosera magnifica', or magnificent sundew.
Amateur researcher Reginaldo Vasconcelos first photographed the sundew plant in a forest on a mountain top in Minas Gerais, southeastern Brazil, in 2013, and posted it on his Facebook page.
Experts identified the plant as a new species, describing it as the second-largest carnivorous plant in the Americas, 'The Telegraph' reported.
"It is the first plant that was discovered on Facebook. It is the largest sundew in the Americas, and the second-largest carnivorous plant in the Americas," said Andreas Fleischmann from the Botanical State Collection of Munich, and co-author of a research paper on the plant.
The plant has a Medusa-like tangle of sticky, carnivorous leaves that can grow up to 24cm in length and ensnare insects the size of a dragonfly.
The scientists were surprised that the large and eye-catching plant species had remained undiscovered for so long, because the mountain on which it was found was easily accessible.
However, the species, which is only found on a single mountain peak, is already considered "critically endangered".
Internet-based image databases have become an "important tool" for plant enthusiasts and botanists to share their interest and knowledge, according to the researchers.
In the majority of cases, photos taken by amateurs are mostly useful in terms of providing location data that would lead to further fieldwork by experts, researchers said.
The discovery of the magnificent sundew, however, is "the first plant species to be recorded as being discovered through photographs on a social network," the researchers said in the study published in the journal Phytotaxa.