The Mystery of Thismia Americana, the Parasitic Plant Found Only in Chicago

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"WHAT HAPPENED TO Thismia americana?"

It's a question that fascinates botanists around the world, but one that few in the general public have probably ever considered, despite the fact that it has been asked for well over a century.

In August 1912, University of Chicago graduate student Norma Pfeiffer was exploring a damp, low-lying prairie near the wetlands surrounding Chicago's Lake Calumet when she spotted a small, glabrous, white plant with delicate streaks of blue-green ringing the mouth of the flower. It was unlike anything else in the surrounding area.

Indeed, as she soon realized after finding additional specimens over the ensuing months, the plant was unlike anything else in the entire country.


THISMIA AMERICANA, as Pfeiffer subsequently dubbed the plant, became the focus of her doctoral thesis. Exhaustively examining the species between 1912 and 1914, she learned that it spent most of its life underground parasitizing fungi dwelling in the damp wetland soils, only briefly peeking above ground in the warmest parts of the summer to flower and reproduce. She also learned that there were a select few species like T. americana, (members of the genus Thismia) and they all lived in tropical areas at lower latitudes.

Pfeiffer was excited to uncover much more about her mystifying botanical outlier. In her thesis, she expressed hope that she could grow the plant in laboratory settings.

"Up to date, the few attempts at germinating the tiny seeds have been fruitless. It is to be hoped that a larger harvest may give a better opportunity for positive results," she wrote.

But two years later, T. americana vanished, a disappearance that coincided with the building of a barn in the vicinity. It has not been spotted since.

MUCH HAS CHANGED since Pfeiffer originally discovered T. americana. In 1924, she moved to Yonkers, New York to work as a research botanist at the Boyce Thompson Institute. There, she published more than five dozen scientific papers over a 35-year career. She passed away at the age of 100 in 1989. By that time, residential and commercial development had completely claimed T. americana's original habitat and encroached on many of the prairies and wetlands in the Lake Calumet area. But that didn't stop amateur botanist and Nature Conservancy steward George Johnson from organizing the first Thismia Hunt in 1991. Every year since, citizen scientists and botanists have teamed up to search for the missing plant. While there have been a couple exciting close calls, the searches have all turned up empty handed.

Johnson isn't surprised. As he told one Thismia Hunt attendee in 2011, the plant probably won't ever be seen again.

"I would sooner expect to see the sun set in the east... I can't imagine us finding it. It was such an unlikely plant to ever be here in the first place... How it got here originally is incomprehensible."

In the last few years, wistful naturalists have speculated on that very topic. Vincent Merckx and Erik Smets of the Naturalis Biodiversity Center in the Netherlands suggest that the minute seeds of ancient Thismia plants in other countries could have been swept up into the air and possibly dispersed by raindrops or ocean currents. They also could have latched on to wildlife traversing the Beringia land bridge between North America and Southeast Asia, later to be swept up in wind or transported by rivers and streams. Regardless of what really happened, we can be certain that Thismia americana had one incredible journey.


The global distribution of Thismia plants.


Sadly, however, it seems the journey has come to an end. The most likely explanation for T. americana's long absence is that it is extinct, yet another victim of human-caused habitat destruction. But many botanists hold out hope for a grand rediscovery, just like what recently happened with T. americana's sibling in Sumatra, Thismia neptunis. First seen in 1866 and lost for over 151 years, it was discovered again in 2017.

George Johnson thinks rediscovering T. americana would spark renewed interest in botany across the globe.

"Botanists from all over the world will take note, be quoted, will be on television. It'll be one of the great plant discoveries."

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