This population of marestail (Conyza canadensis) along the Monon Trail is so unusually robust I'm going to call it a marestail forest. It rivals the marestail of any Indiana farmyard. Pictures taken August 14, 2010, along the Monon Trail, just south of 86th St., Marion County.
Conyza canadensis is high in the essential oil limonene:
The tiny daisylike flowers of Conyza canadensis put this plant in the family Asteraceae.