One of their interesting finds was the abundant fossilized remains of a species of Equisetum. Not only were dense stands of aerial stems discovered, but also a wide variety of organsincluding leaf sheaths, roots and rhizomes, branches, apices, and strobili (reproductive parts)were found intricately preserved in blocks of chert.
"Because these plants were located in a hot spring," notes Channing, "the normal preservation processes were replaced by a process of cellular permineralizationplant tissues and cells were permeated by water containing dissolved silica, which was precipitated prior to plant decay and resulted in magnificent three-dimensional preservation of complete plants."
By cutting, polishing, and thinly sectioning blocks of chert (layers of crystallized silica formed by the ancient hot springs) from the deposit and then examining the preserved fossils with high-powered microscopes, the authors were able to describe in intricate detail the anatomy and morphology of a Jurassic Equisetum for the first time.
The authors discovered that in many ways the morphology and anatomy of this fossilized Equisetum is indistinguishable from those of species living today in two subgenera, Equisetum and Hippochaete. For example, it was evergreen, grew upright in a single straight stem, and had a double endodermis. Yet, there were some features that did not fit with any extant or fossil species of Equisetumthus justifying the erection of a new species: Equisetum thermale.
"Equisetum thermale appears to be the oldest record of the genus Equisetum and at the very least, records that anatomically, essentially modern Equisetumlike horsetails have a histo
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American Journal of Botany