The foxtails are the #1 weed problem in Iowa, and either the #1 or #2 weed problem in
the US (along with the pigweed species-group). Literally every field, waste area,
residental yard, roadside and golf course in Iowa has an infestation of foxtails.
The foxtails probably arose in Africa. A primal foxtail relative probably similar to green foxtail then spread from the African continent to Eurasia, soon infesting areas of Asia, Europe, India, Russia and most other areas. The plant was domesticated as a grain, today it is often used as a rice substitute grain in many areas of China, Japan, India and Africa. From Eurasia, immigrants to the US brought the foxtail species in there luggage, in there cuffs and pockets, and it spread across the American continent. A similar introduction occurred in Central and South America. Only knotroot foxtail, almost identical to yellow foxtail, probably arose independently in the American continents.
Today, the weedy foxtails infest vast areas around the world. Our weedy species are found around the northern temperate regions of the world.
To learn more about how to ID this highly diverse and successful weed group please take a look at:
To learn more about why the foxtails or so incredibly successful around the world take a gander at this material: