The Cacti at Rainbow Beach Dunes

A small Opuntia Humifusa plant at Rainbow Beach Dunes

A small Opuntia Humifusa plant at Rainbow Beach Dunes

Perhaps unsurprisingly, my strongest impressions and most pressing questions following our visit to Rainbow Beach Dunes are about the “sexiest”[1] Professor Alison Anastasio part of the dunes: Opuntia Humifusa, more commonly known as Eastern Prickly Pear Cactus.[2]https://en.wikipedia.org/wiki/Opuntia_humifusa

I was interested by the impressive abundance of the cacti at the site we visited, especially when I discovered that its abundance is not consistent across its range. The prickly pear cactus has no unusual legal status at the federal level, but it is listed as rare vulnerable, or endangered in three states.[3]“Species: Opuntia Humifusa.” U.S. Forest Service Fire Effects Information System. United States Department of Agriculture, n.d. Web. 23 May 2016.  The cactus owes its abundance in part to its ability to reproduce in three different ways.[4]Ibid.  O. Humifusa can reproduce through pollination and seeding. Detached segments can also travel on passing animals or simply fall off and roll away, taking root nearby. A third option called “layering,” in which still attached segments input new roots into the soil, explains why it is so difficult to distinguish adjacent plants from one another.

Opuntia humifusa is just one of many dozens of species in the Opuntia genus. Clive Innes & Charles Glass, the “World’s Leading Authorities on Cacti” according to the cover of their book, have images over 75 species in their book Cacti.[5] Innes, Clive, and Charles Glass. Cacti. New York: Portland House, 1991. Print.  There is a hot debate that still appears to be unresolved about whether the cylindrical “Cholla” cacti of the desert southwest deserve to be grouped into Opuntia.  While some books that I referenced included them, other scholars have taken to grouping them into a separate but similar genus: Cilindropuntia.[6]Loflin, Brian, and Shirley Loflin. Texas Cacti. Vol. 42. N.p.: Texas A&M UP, 2009. Print.  Either way, O. humifusa continues to play a unique role in eastern biological communities like these dunes while its many relatives compete to fill similar niches in the desert southwest.

Calumet Quarter students counting and recording prickly pear cacti at Rainbow Beach Dunes.

Calumet Quarter students counting and recording prickly pear cacti at Rainbow Beach Dunes.

Opuntia Humifusa has been used in past restoration projects and seems to do particularly well in times of drought when other species struggle.[7]“Species: Opuntia Humifusa.” U.S. Forest Service Fire Effects Information System. United States Department of Agriculture, n.d. Web. 23 May 2016.  I am curious as to whether the recent drastic fluctuations in Chicago’s annual rainfall have anything to do with the combined abundance of cacti and the poor health of many of the cacti.[8]“Northeast Illinois – Annual Precipitation.” Illinois State Water Survey. State Climatologist Office of Illinois, n.d. Web. 23 May 2016.

A final fact about this versatile plant is that prickly pear is also edible if prepared correctly. To conclude, here is a link to a recipe for Cactus Quesadillas that calls for canned prickly pear so that even our readers in Canada can access this tasty treat.

Footnotes   [ + ]

1. Professor Alison Anastasio
2. https://en.wikipedia.org/wiki/Opuntia_humifusa
3, 7. “Species: Opuntia Humifusa.” U.S. Forest Service Fire Effects Information System. United States Department of Agriculture, n.d. Web. 23 May 2016.
4. Ibid.
5. Innes, Clive, and Charles Glass. Cacti. New York: Portland House, 1991. Print.
6. Loflin, Brian, and Shirley Loflin. Texas Cacti. Vol. 42. N.p.: Texas A&M UP, 2009. Print.
8. “Northeast Illinois – Annual Precipitation.” Illinois State Water Survey. State Climatologist Office of Illinois, n.d. Web. 23 May 2016.