Amazonian tree with human-sized leaves finally gets ID’d as new species
At the National Institute of Amazonian Research (INPA) in Manaus, Brazil, a framed exhibit of a massive dried leaf has been a local attraction for decades. But the complete identity of the tree it belongs to remained unresolved — until now.
Researchers have known that the tree is a species of Coccoloba, a genus of flowering plants that grow in the tropical forests of the Americas. Botanists from INPA first encountered an individual of the unknown Coccoloba tree in 1982 while surveying the Madeira River Basin in the Brazilian Amazon. They spotted more individuals of the plant over subsequent expeditions in the 1980s. But they couldn’t pinpoint the species at the time. The individual trees weren’t bearing any flowers or fruits then, parts that are essential to describing a plant species, and their leaves were too large to dehydrate, press and carry back to INPA. The researchers did take notes and photographs.
In 1993, botanists managed to finally collect two large leaves from a tree in the state of Rondônia, which they then framed for public viewing at INPA. “The species became locally famous, but due to the lack of reproductive material it could not be described as a new species for science,” Rogério Gribel, a researcher at INPA, told Mongabay in an email.
It was more than a decade later, in 2005, that Gribel and his colleague, Carlos Alberto Cid Ferreira, collected some seeds and dying flowers from a tree in Jamari National Forest. Again, these materials weren’t good enough to describe the plant species. So they sowed the seeds at the INPA campus, grew the seedlings, and waited. Their patience bore fruit 13 years later. Literally.
In 2018, one of the planted trees flourished and fruited, Gribel said, finally giving them the botanical material they needed to describe the new species.
“We are very happy and proud that after the long period of ‘tracking’ such a peculiar and relatively rare species we have finally succeeded in obtaining the flowers and fruits that are the essential structures for describing a new species for science,” he said.
Gribel and his colleagues, who described the species in a recent paper published in Acta Amazonica, have named it C. gigantifolia in reference to the plant’s giant leaves.
The researchers say that C. gigantifolia, which grows to about 15 meters (49 feet) in height and has leaves that can reach 2.5 meters (8 feet) in length, likely has the largest known leaf among dicotyledonous plants — a large group of flowering plants that include sunflowers, hibiscus, tomatoes and roses. These plants have seeds that can be split into two identical halves, each forming the first two embryonic leaves of the seedling, and their leaves generally have branched veins. The seeds of monocotyledonous plants, by contrast, give out a single embryonic leaf and the grown plants’ leaves have parallel veins, such as those of palm trees, grasses, orchids and bananas.