Nov. 28, 2017

water lettuce, Pistia stratiotes

This member of our hit list has newly arrived in Michigan, in the Detroit River and lakes in Lenawee and Jackson Counties. Sue Thompson in FNA reports an American native range of FL, LA, and TX. She regards other reports as cultivated escapes not likely to survive the winter. It's considered invasive because it can quickly cover still water, choking navigation, fishing, and other species. How self centered we are! We list it and kill it for doing what it has done in those southern states for longer than man has been here. The flower spike is the tiny structure in the white bract. The bract, analogous to that of a calla lily, is at most a quarter inch across. Water lettuce has been reported as escaped in AZ, CA, CO, CT, DE, GA, HI, KS, MD, MI, MO, MS, NC, NJ, NY, OH, and SC. This is a pantropical species. Fossil records from tropical strata have been found around the world.
Cultivated, Lenawee Co MI, 5/14/17.