Spring is in the air. And so is pollen. Local plants put forth an abundance of the stuff in a bid to ensure their continued existence, even in the hardest concrete jungles.
Now research shows that immigrants do much of the dusting in big cities. Ecologists at Butler University looked at 70 years of dried plant specimens from their home town, Indianapolis. The overall number of plant species stayed roughly the same, even as Indianapolis became a real polis.
But native species disappeared at a rate of roughly two per year, while more than one newcomer arrived. Examples include the queen of the prairie, wands of pink flowers last seen growing in Indianapolis in 1935. Newcomers include Japanese knotweed and Amur bush honeysuckle.
The research was published in the March 18 issue of the "Journal of Ecology".
Of course, roughly 200 years ago, Indianapolis was an upland forest of beech and maple. Those trees are still present in small numbers, but the vast woodlands of the eastern Midwest are long gone to farmland and city. In a city, the only constant is change.