A Gnat in Amber With an Important Stowaway: Ancient Orchid Pollen

Orchids are much older than we thought.

A product of the Cretaceous.
A product of the Cretaceous. Barney Moss/CC BY 2.0

This fungus gnat did not have a good day. First, she was duped into laying her eggs in an orchid instead of a mushroom, then she lost a leg, and finally she died, stuck in some tree sap. But between 45 and 55 million years later, her bad day is telling scientists that they need to reconsider the age of the orchid family. That tree sap preserved for the ages a pollen sac attached to the gnat’s leg, and it is the earliest known evidence of the diverse family of flowering plants.

The round object under the fungus gnat's abdomen is an orchid pollinia.
The round object under the fungus gnat’s abdomen is an orchid pollinia. GEORGE POINAR, OREGON STATE UNIVERSITY

Amber, fossilized tree sap, is really good at preserving things. In it, scientists have found ancient mammal blood inside a tick, a dinosaur feather, and plenty of insects and lizards. Orchid pollen sacs have been found in amber before, also attached to insects. But the previous oldest known specimen was found in Dominican amber that’s 20 to 30 million years old. The new specimen, found in Baltic amber, is about twice as old.

“It wasn’t until a few years ago that we even had evidence of ancient orchids because there wasn’t anything preserved in the fossil record,” said George Poinar Jr., an entomologist at Oregon State University who led the study, in a press release. The sticky pollen sac, known as a pollinia, is a common feature of modern orchids, which use a variety of evolutionary tricks to attract pollinators and get their pollen from one flower to another. But finding such an old example of a pollinia shows that the orchid family was pretty well-evolved when the gnat got stuck, back when palm trees grew in Alaska and India was just butting into Asia. That means the first orchids were probably blooming back during the Cretaceous, when dinosaurs were still at the top of the food chain.

Today there are around 28,000 species of orchid, and some of them are still up to their incredibly old ruses, fooling modern fungus gnats into picking up pollinia.