Originally, the Boulder Valley was covered in short-grass prairie. Irrigation ditches changed that. Now water-loving riparian plants follow the lines of irrigation ditches and spread across the Boulder Valley into irrigated fields.
Non-native plants, also called "exotics," thrive along ditches. Sometimes exotics are 90% of the species in plant counts.
Some of these exotic species have been here for over 100 years. Does that make them "natural" or "native?" How long do they have to live here before they are considered "native?"
Right: Brown above, green below the Davidson Ditch, Cherryvale Rd.