A 20th Century Extinction: Thismia americana, fungus-feeding plant

I made a bet with myself that I could find an interesting North American plant species that went extinct in the last 100 years.  It took only about 5 minutes to win the bet.

In 1913, botanist Norma Pfeiffer earned her PhD from the University of Chicago at age 24. 

There’s so much impressive material in that last sentence that I’d recommend you read it again. 

Ok, now we can continue.  Dr. Pfeiffer would go on to become an expert on lilies (so says the New York Times), but it’s her PhD work that’s relevant here.  As part of her thesis, Dr. Pfeiffer discovered the species Thismia americana right in Chicago.

Why was — and is — T. americana noteworthy?  We’ll let Dr. Pfeiffer explain first in her 1914 paper “Morphology of Thismia americana“:

The entire plant is glabrous and white, save in the 6 divisions of the perianth, where free, and in the disk closing the perianth mouth.  Here there is a delicate blue-green color, deeper in the raised ring about the aperture of the disk. …

In the older part of a root of Thismia, there is evident a very conspicuous epidermis. … The layer of cells immediately below the epidermis is packed with the thick-walled, branching mycelium of a coarse fungus. …

Since the fungi occur in the root, the absorptive region, and not in the stem, they would seem to have some connection with water and food supply.

Hm.  A 2004 story in the publication Chicago Wilderness uses lay language:

Thismia americana was a mystery right from its discovery. Instead of drawing energy from the sun, Thismia fed on fungi that grew in its roots, spending much of the year underground. In midsummer, a tiny tube-like flower pushed upward an inch or so, and only the upper quarter actually emerged from the soil. Its three petals remained linked at the top of the tube, leaving arch-like entries for small insects to pollinate. Lacking chlorophyll, the entire plant was smooth and translucent white, with hints of pale blue-green stripes that deepened at the tip of the flower. By September, the blossoms seeded and withered, and the plant disappeared underground for another year.

Or, if you prefer, here’s the Chicago Tribune in 1991:

What makes the plant so unusual is that by all rights it should never have grown here. Its nearest relative is a tropical plant that is found in New Zealand, Australia and Tasmania. It contains no chlorophyll, the substance that allows other plants to make their own food and gives them their green color. Instead, thismia lives on soil nutrients that a fungus in its roots digests for it.

A plant that mostly lived underground, lacked chlorophyll, and instead of producing its own food ate only courtesy of root fungi?  Pretty neat.

Thismia Americana “was seen for five consecutive years, and it has never been found again despite repeated searches by scientists and botanical groups” [pdf]; accordingly, it is now generally believed to be extinct.


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