Jan Scholten

English: Horsetails.
Botany: vascular plant; ± 410 million years old; reproduce by shedding spores; bear a protostele; having microphylls, leaves that have only a single vein.
class of plants with a fossil record going back to the Devonian; wet areas, with needle-like leaves radiating at regular intervals from a single vertical stem.

Equisetales is an Order in the Class Pteridophyta.
In the Plant theory Equisetales is the only Order in the Class Equisetidae. The division in Subphases is limited as only one family, Equisetaceae, is surviving at the moment. Equisetaceae are placed in Subphase 4. This shows the prominent quality of Silicon, being in Subphase 4 in the Silicon series, just as Equisetaceae is. Equisetum is the plant having the highest content of Silicon of all known plants, up to 80%.
Equisetales shows also the prominent place of Subphase 4 in general, the Phase that is the strongest, most vital and longest surviving. Phase 4 is the most alive, showing what it is, without hesitation and retirement.

4. Equisetaceae: Equisetum.