An Extinction in Chicago

Chicago may seem like a strange place for the last stronghold of a plant species, however, that was the case back in 1916. In 1912, a graduate student by the name of Norma Pfeiffer was exploring a wet prairie near Torrence Avenue in Chicago when she stumbled across something peculiar. What she found had completely stumped the botany department. Her description of this little mystery ended up earning her a Ph.D.

What she had discovered was indeed a plant, but it was like nothing else known in this region. The plant was named Thismia americana. T. americana, like all member of the Burmanniaceae family, is a mycoheterotroph. It made its living by parasitizing mycorrhizal fungi in the soil. Because of this lifestyle, T. americana did not bother with leaves or even chlorophyll. It simply stored up enough energy to produce its tiny translucent white and blue-green striped little flower, which barely breached the soil surface.

The oddest thing about finding a Thismia growing in Illinois (let alone in Chicago) is that the family with which this plant belonged is very much tropical in its distribution. Its closest living relatives grow only in Australia, New Zealand, and Tasmania (the color picture below). What was this odd little species doing in northern North America? Pfeiffer continued to encounter and examine these plants for another 5 years after her initial discovery. Sadly, 1916 was the last year that anyone ever saw these plants again. The site in which the original population was found has since been developed.

There have been many repeated attempts at rediscovering this species. In 1949, Pfeiffer herself worked with a team of botanists in an attempt to find new populations of T. americana. They were unsuccessful. Another search was launched in the early 1990's. Volunteers were given pictures and models of the plant in hopes that they could develop a search image. They were also tested using small bluish-white beads scattered around prairie vegetation to see if they were even capable of finding a flower as small as T. americana's. Just as in 1949, no Thismia were found (nor were most of the beads apparently) though the team did turn up at least 17 plant species never recorded in that region before. Their time was not wasted. Similar searches in 2002 and 2011 have produced similarly disappointing results.

How and why this species came to be part of the prairies of Illinois will forever remain a mystery. Many have tried to find it since. All have failed. Some still hold out hope that a small remnant population remains somewhere hidden beneath goldenrods and various grasses. Given the size and appearance it is easy to see how such a plant could be overlooked. If anything, Thismia americana stands as a reminder of how important even the smallest nature preserves can be. For species like this, the simple act of preserving a chunk of land smaller than a city block could have made all the difference.

Photo Credit: Tindo2 (http://bit.ly/1wmHiWu), Mark Mohlenbrock and http://www.chicagowilderness.org

Further Reading:
http://www.jstor.org/stable/2468713…

http://www.jstor.org/stable/2469255…

http://www.jstor.org/discover/10.1086/674315…

http://www.chicagowilderness.org/…/…/summer2004/thismia.html