A strange tree found in the Manu National Park in Peru in 1973 is a new genus and species of the small, mainly neotropical plant family Picramniacea, according to new research.
Aenigmanu alvareziae in the Amazon rainforest. Image credit: Patricia Álvarez-Loayza.
The new tree species, named Aenigmanu alvareziae, is about 6 m (20 feet) tall, with tiny orange fruits shaped like paper lanterns.
“When I first saw this little tree, while out on a forest trail leading from the field station, it was the fruit — looking like an orange-colored Chinese lantern and juicy when ripe with several seeds — that caught my attention,” said Dr. Robin Foster, a researcher with the Smithsonian Tropical Research Institute who originally collected the mystery plant in Peru’s Manu National Park.
“I didn’t really think it was special, except for the fact that it had characteristics of plants in several different plant families, and didn’t fall neatly into any family.”
“Usually I can tell the family by a quick glance, but damned if I could place this one.”
The mystery plant sat in the herbarium of the Field Museum for years, but Dr. Foster and colleagues didn’t forget about it.
A leaf and tiny orange fruit of Aenigmanu alvareziae. Image credit: Patricia Álvarez-Loayza.
In the new study, they analyzed DNA of Aenigmanu alvareziae using dried and fresh specimens.
The analysis revealed that the plant’s closest relatives were in the Picramniaceae family, which was a big deal to the botanists because it didn’t look anything like its closest relatives, at least at first glance.
“Looking closer at the structure of the tiny little flowers I realized, oh, it really has some similarities but given its overall characters, nobody would have put it in that family,” said Dr. Nancy Hensold, a botanist at the Field Museum.
The researchers then sent specimens to New York Botanical Garden’s Dr. Wayt Thomas, an expert in Picramniaceae.
“When I opened the package and looked at the specimens, my first reaction was, ‘What the heck?’ These plants didn’t look like anything else in the family,” Dr. Thomas said.
“So I decided to look more carefully — once I looked really carefully at the tiny, 2-3-mm long flowers, things fell into place.”
Finally getting a scientific classification for Aenigmanu alvareziae could ultimately help protect the Amazon rainforest in the face of deforestation and climate change.
“Plants are understudied in general. Especially tropical forest plants. Especially Amazon plants. And especially plants in the upper Amazon,” Dr. Foster said.
“To understand the changes taking place in the tropics, to protect what remains, and to restore areas that have been wiped out, plants are the foundation for everything that lives there and the most important to study.”
“Giving them unique names is the best way to organize information about them and call attention to them.”
“A single rare species may not by itself be important to an ecosystem, but collectively they tell us what is going on out there.”
A paper on the discovery was published in the journal Taxon.
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William Wayt Thomas et al. Aenigmanu, a new genus of Picramniaceae from Western Amazonia. Taxon, published online October 6, 2021; doi: 10.1002/tax.12588
