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It only took digitizing more than 500,000 samples of fruits, flowers, and leaves that were collected over more than 300 years, but scientists now believe they have a relatively comprehensive list of all the tree species in the Amazon.

The 11,676 species described

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An aerial view of the Amazon Rainforest near Manaus, the capital of the Brazilian state of Amazonas.

in the study represent about 25% of the estimated total number of tropical tree species in the world, making the river basin a true biodiversity hotspot. By comparison, Europe has only 124 native tree species.

Here’s Nicholas St. Fleur, reporting for the New York Times:

“Before this paper we didn’t have a list of Amazonian trees,” said Nigel Pitman, a tropical forest ecologist at the Field Museum in Chicago, and an author of the study. “With this list we are answering ‘How many species have been found?’ and ‘What are they?’ ” Dr. Pitman and his team combed through hundreds of thousands of digital records from museums around the world to create their catalog. The oldest samples were collected in 1707 and the most recent were obtained in 2015.

The new results support the idea that there may be another 4,000 or so tree species lurking in the Amazon; another recent study suggested that the total is closer to 16,000.

Some of those specimens might still be in museum or herbarium drawers, waiting to be digitized. Others may be in regions that haven’t been sampled—perhaps they are difficult to reach—and sampling certainly hasn’t been as randomly distributed across the entire 123,500 square miles included in the study as statisticians would like.

But the study isn’t over, in a way. Pitman points out that the database they’ve created is really more of a starting point, a list of species and where they occur to which other botanists can add.