Author: Jan Scholten
Name: Equisetopsida; Equisetophyta; Arthrophyta; Sphenophyta; Sphenopsida.
English: eusporangiate ferns; Horsetails and primitive ferns.
Botany: vascular plant; ± 410 million years old; reproduce by shedding spores; bear a protostele; having microphylls, leaves that have only a single vein; typically grow in wet areas, with needle-like leaves radiating at regular intervals from a single vertical stem.
Equisetidae, Equisetopsida were formerly regarded as a separate division of spore plants. Today Equisetidae are seen as close relatives of and included in the typical ferns, Pteridopsida.
In the Plant theory Equisetidae is treated as a Class in the Phylum Pteridophyta. Equisetales, with 1 Family, Equisetaceae and 1 genus, Equisetum is the main Order in the Class Equisetidae. Equisetales is placed in Phase 4. The position similarity with Silicon in the Periodic table is strong. The other Orders are placed tentatively.
Equisetidae have an emphasis on the Silicon series beside the quality of the Iron series.
They have a conflict between their own family and the community.
1. Psilotaceae: only Family in Pislotales; Whisk ferns; 2 genera, Psilotum, Tmesipteris.
4. Equisetaceae: only Family in Equisetales; 1 genus: Equisetum.
5. Marattiaceae: only Family in Marattiales; 6 genera, Angiopteris, Christensenia, Danaea, Marattia, Eupodium, Ptisana.
7. Ophioglossaceae: only Family in Ophioglossales; 4 genera, Ophioglossum, Botrychium, Helminthostachys, Mankyua.