3D model of a fossil stem of a giant horsetail plant (NHMW-GEO-2024/0188/10966)

<p>This is the fossil stem of a giant horsetail plant: <i>Calamites communis</i>. These plants are closely related to ferns, so they produce spores rather than seeds. Today, there are only 18 species of horsetails, all of which are small (typically less than 1 m tall) and belong to a single genus: <i>Equisetum</i>. But, during the Carboniferous Period (359–299 million years ago), there were hundreds of species of horsetails, and they could be huge, with some growing up to 30 m tall!</p><p>This object is part of the historical ‘Ettingshausen collection’, which is on permanent loan from the Institute of Biology, University of Graz.&nbsp;</p>