Horsetail

This strange thing on this picture is the sporophyte (i.e. the spore producing part) of a field horsetail (Equisetum arvense).

It is a plant, whose ancestors once were numerous and tall. Nowadays still 25 species are left over worldwide -the last abating of this once large group of plants. And even those 25 nearly haven't changed over the last 300 million years.

The species on the picture grows with a rhizome deep in the earth and so is nearly unrootable and an awful weed on fields and in gardens. I took the picture in april 2000 on a meadow on a Rhine dam near Bonn-Beuel (germany).