A great part of our fossil fuels is based on distant relatives from our present horsetails. During the Carboniferous, this group of plants attained almost worldwide distribution: arborescent lifeforms up to 30m. The decay of these trees under anaerobic conditions, later additionally under high pressure and high temperatures finally formed coal, still one basis of fossil energy.
Today the horsetails are worldwide in distribution except for parts of Australasia. In Middle Europe a plant height of 1m is remarkable.
The most conspicuous morphological feature of a horsetail is the segmentation of the shoot into nodes and internodes. This is why these plants are also called the “articulate”.
Equisetum telmateia Equisetum telmateia (note the jointed stem)
