According to CNN the black smoke is the result of a fire burning a particular weed whose leaves contain an oily substance.
So whats the weed?
Let’s all hope it isn’t poison ivy. That smoke contains the irritant oils that make your skin inflame, and the smoke can enter your lungs.
The most common growth in the Mentor Marsh is reed grass (Phragmites australis), growing over eight feet tall. There is also a variety of cattail that is pretty common, there.
Cleveland Museum of Natural History article on Mentor Marsh that mentions the fire from 11 years ago.
[url =http://www.hort.agri.umn.edu/h5015/97papers/robertson.html] This page says that burning cattails would be the source of the black smoke:
