Equisetidae
[2] They typically grow in wet areas, with whorls of needle-like branches radiating at regular intervals from a single vertical stem.In the only extant genus Equisetum, these are small leaves (microphylls) with a singular vascular trace, fused into a sheath at each stem node.[5] Very rapid internode elongation results in the formation of a pith cavity and a ring of carinal canals formed by disruption of the primary xylem.In extinct groups, further protection was afforded to the spores by the presence of whorls of bracts - big pointed microphylls protruding from the cone.[3] (This distinction is necessary because of the alternative usage of Equisetopsida sensu lato as a synonym for all land plants (Embryophyta) with rank of class.The consensus classification produced by the Pteridophyte Phylogeny Group in 2016 also places horsetails in the subclass Equisetidae, but in the class Polypodiopsida (ferns broadly defined).The Equisetales existed alongside the Sphenophyllales, but diversified as that group disappeared into extinction, gradually dwindling in diversity to today's single genus Equisetum.The organisms first appear in the fossil record during the late Devonian,[1] a time when land plants were undergoing a rapid diversification, with roots, seeds and leaves having only just evolved.
N = node,
I = internode,
B = branch in whorl,
L = fused microphylls
Equisetopsida sensu latoLate DevonianPreꞒEquisetum telmateiaScientific classificationPlantaeTracheophytesPolypodiophytaPolypodiopsidaEquisetalesArchaeocalamitaceaeCalamitaceaeEquisetaceaePseudobornialesSphenophyllalesSynonymssubclassesvascular plantsDevoniandivisionleavesmicrophyllsmegaphyllsSphenophyllumvascular bundleseusteleconvergentlyphloemcambiumEquisetumrhizomesstrobilibractshomosporousheterosporousdehiscenceelatershygroscopicstrobilussporangiophoressporangiamolecular studiesphylogenetic analysispteridophytemolecular phylogeneticclassessensu strictoRevealOphioglossidaeMarattiidaePolypodiidaeEarly CretaceousJurassicmonotypicCarboniferousearly PermianEvolutionary history of plantsBibcodeAnnals of BotanyChase, Mark W.Reveal, James L.Botanical Journal of the Linnean SocietyArchaeplastidaPlantae s.l.DomainDiaphoretickesAmorpheaPicozoaPicomonasRhodelphidiaRhodelphisRhodophytaCyanidiophyceaeProteorhodophytinaPorphyridiophyceaeStylonematophyceaeCompsopogonophyceaeRhodellophyceaeEurhodophytinaBangiophyceaeFlorideophyceaeGlaucophytaGlaucocystophyceaeAlgospongiaViridiplantaePlantae s.s.green algaePrasinodermophytaPrasinodermophyceaePalmophyllophyceaeChlorophytaMamiellophyceaePyramimonadophyceaeNephroselmidophyceaePicocystophyceaeChloropicophyceaePedinophyceaeChlorodendrophyceaeUTC cladeUlvophyceaeTrebouxiophyceaeChlorophyceaeStreptophytaMesostigmatophyceaeChlorokybophyceaeSpirotaeniaKlebsormidiophyceaePhragmoplastophytaCharophyceaeColeochaetophyceaeZygnematophyceaeEmbryophytaEmbryophytesPlantae sensu strictissimoBryophytesMarchantiophytaHaplomitriopsidaMarchantiopsidaJungermanniopsidaAnthocerotophytaLeiosporocerotopsidaAnthocerotopsidaBryophytaTakakiopsidaSphagnopsidaAndreaeobryopsida