New Guinea has more known plant species than any island in the world

To find the island with the most known plant species in the world, head to New Guinea.

Not only is New Guinea home to feathered marvels like birds of paradise and cassowaries, the island is also brimming with foliage. Now the first verified count of the flora growing there reveals that New Guinea hosts more than 13,600 vascular plant species — plants like trees and shrubs that have specialized tissue to transport nutrients.  

That new inventory shows that New Guinea, which includes Papua New Guinea and Indonesian New Guinea, has the highest known plant diversity of any island on Earth, researchers report August 5 in Nature. The survey documented 19 percent more plant species than have been recorded in Madagascar and 22 percent more than Borneo — regions that also rank among the most biodiverse on Earth.

The new accounting could help experts preserve the region’s stunning biodiversity (SN: 9/26/19), the researchers say.

From herbs that produce some of the world’s largest bananas to orchids with appendages that look like spiders, New Guinea is filled with astounding examples of botanical specimens. “This region is really just amazing,” says Rodrigo Cámara-Leret, a botanist at the University of Zurich. “Knowing what [plant life] exists is the first step to value what people are surrounded by.”

Cámara-Leret and 98 other researchers inspected and identified nearly 705,000 plant specimens from New Guinea, the world’s largest tropical island. Overall, the team identified 13,634 species, more than two-thirds of which are endemic, found only on the island. Most of the identified plants were trees, which made up 29 percent of species, closely followed by herbs and plants known as epiphytes that grow on other plants.

Flora forms

Most of the plants that experts identified on New Guinea were trees, herbs or plants called epiphytes that grow on other plants, which together account for 77 percent of the species. Here, all of the plant species are separated into one of seven life-forms: trees, herbs, epiphytes, shrubs, climbers, palms and tree ferns. Each box in the grids below the illustrations represents 1 percent.

Classification of plants in New Guinea by life-form

And there’s still more flora to uncover. The team estimates that over the next 50 years, botanists will add between 3,000 to 4,000 species to the list.

It’s impressive to think that there’s still so many species to discover on the diverse island, Cámara-Leret says. “Every time a botanist goes out there, new species are popping up.”