Editing Equisetum (section)

==Taxonomy==
===Species===
Currently, 18 species of ''Equisetum'' are accepted by [[Plants of the World Online]].<ref name=powo/> The living members are divided into three distinct lineages, which are usually treated as [[Subgenus|subgenera]]. The name of the type subgenus, ''Equisetum'', means "horse hair" in [[Latin]], while the name of the other large subgenus, ''Hippochaete'', means "horse hair" in [[Ancient Greek|Greek]]. [[Hybrid (biology)|Hybrid]]s are common, but hybridization has only been recorded between members of the same subgenus.<ref>{{Cite web
|url=http://www.btinternet.com/~pigott/equisetum/taxonsum.html|title=Summary of ''Equisetum'' Taxonomy|last=Pigott|first=Anthony|date=4 October 2001|website=National Collection of Equisetum|archive-url=https://web.archive.org/web/20121021201939/http://www.btinternet.com/~pigott/equisetum/taxonsum.html|archive-date=21 October 2012|url-status=dead|access-date=17 June 2013}}</ref>

Two ''Equisetum'' plants are sold under the names ''Equisetum japonicum'' (barred horsetail) and ''Equisetum camtschatcense'' (Kamchatka horsetail). These are both types of ''E.&nbsp;hyemale'' var. ''hyemale'', although they may also be listed as separate varieties of ''E.&nbsp;hyemale''.<ref>{{cite book |last1=Trounce |first1=Bob |last2=Hanson |first2=Cindy |last3=Lloyd |first3=Sandy |last4=Iaconis |first4=Linda |last5=Thorp |first5=John |title=Horsetails - ''Equisetum'' species |url=https://profiles.ala.org.au/opus/weeds-australia/profile/Equisetum%20spp. |website=WeedsAustralia |publisher=[[Atlas of Living Australia]], Centre for Invasive Species Solutions |format=PDF |date=2003 |isbn=1-920932-24-0 |access-date=2021-08-26 |archive-date=2021-08-26 |archive-url=https://web.archive.org/web/20210826185746/https://profiles.ala.org.au/opus/weeds-australia/profile/Equisetum%20spp. |url-status=dead }}</ref>{{Citation needed|date=October 2016}}

[[Image:Equisetum hyemale 02 by Line1.jpg|thumb|right|''[[Equisetum hyemale]]'' (rough horsetail) in [[Parc floral de Paris]]]]

=== Evolutionary history ===
The oldest remains of modern horsetails of the genus ''Equisetum'' first appear in the Early Jurassic, represented by ''[[Equisetum dimorphum]]'' from the Early Jurassic of Patagonia<ref>{{Cite journal|last1=Elgorriaga|first1=Andrés|last2=Escapa|first2=Ignacio H.|last3=Bomfleur|first3=Benjamin|last4=Cúneo|first4=Rubén|last5=Ottone|first5=Eduardo G.|date=February 2015|title=Reconstruction and Phylogenetic Significance of a New Equisetum Linnaeus Species from the Lower Jurassic of Cerro Bayo (Chubut Province, Argentina)|url=http://www.bioone.org/doi/10.5710/AMGH.15.09.2014.2758|journal=Ameghiniana|language=en|volume=52|issue=1|pages=135–152|doi=10.5710/AMGH.15.09.2014.2758|bibcode=2015Amegh..52..135E |issn=0002-7014|s2cid=6134534|hdl=11336/66623|hdl-access=free}}</ref> and ''[[Equisetum laterale]]'' from the Early-Middle Jurassic of Australia.<ref>Gould, R. E. 1968. Morphology of ''Equisetum laterale'' Phillips, 1829, and ''E. bryanii'' sp. nov. from the Mesozoic of south‐eastern Queensland. Australian Journal of Botany 16: 153–176.</ref><ref name="Elgorriaga-2018">{{Cite journal|last1=Elgorriaga|first1=Andrés|last2=Escapa|first2=Ignacio H.|last3=Rothwell|first3=Gar W.|last4=Tomescu|first4=Alexandru M. F.|last5=Rubén Cúneo|first5=N.|date=August 2018|title=Origin of Equisetum : Evolution of horsetails (Equisetales) within the major euphyllophyte clade Sphenopsida|journal=American Journal of Botany|language=en|volume=105|issue=8|pages=1286–1303|doi=10.1002/ajb2.1125|pmid=30025163|doi-access=free}}</ref> [[Petrifaction|Silicified]] remains of ''[[Equisetum thermale]]'' from the Late Jurassic of Argentina exhibit all the morphological characters of modern members of the genus.<ref>{{Cite journal|last1=Channing|first1=Alan|last2=Zamuner|first2=Alba|last3=Edwards|first3=Dianne|last4=Guido|first4=Diego|date=2011|title=Equisetum thermale sp. nov. (Equisetales) from the Jurassic San Agustín hot spring deposit, Patagonia: Anatomy, paleoecology, and inferred paleoecophysiology|journal=American Journal of Botany|language=en|volume=98|issue=4|pages=680–697|doi=10.3732/ajb.1000211|issn=1537-2197|pmid=21613167|doi-access=free|bibcode=2011AmJB...98..680C |hdl=11336/95234|hdl-access=free}}</ref> The estimated split between ''[[Equisetum bogotense]]'' and all other living ''Equisetum'' is estimated to have occurred no later than the Early Jurassic.<ref name="Elgorriaga-2018" />

====Subgenus ''Paramochaete''====
* {{txil|Equisetum bogotense|[[Carl Sigismund Kunth|Kunth]]}} – Andean horsetail; upland [[South America]] up to [[Costa Rica]]; includes ''E.&nbsp;rinihuense'', sometimes treated as a separate species. Previously included in subg. ''Equisetum'', but Christenhusz ''et al.'' (2019)<ref name="Christenhusz2019" /> transfer this here, as ''E.&nbsp;bogotense'' appears to be sister to all the remaining species in the genus.

====Subgenus ''Equisetum''====
* {{txil|Equisetum arvense|[[Carl Linnaeus|L.]]}} – field horsetail or common horsetail; circumboreal down through temperate zones
* {{txil|Equisetum braunii|[[Carl August Julius Milde|Milde]]}} – northern giant horsetail, syn. ''E. telmateia'' subsp. ''braunii'' (Milde) Hauke.; west coast of North America
* {{txil|Equisetum diffusum|[[David Don|D.Don]]}} – Himalayan horsetail; Himalayan India and China and adjacent nations above about {{convert|450|m}}
* {{txil|Equisetum fluviatile|L.}} – water horsetail; circumboreal down through temperate zones
* {{txil|Equisetum palustre|L.}} – marsh horsetail; circumboreal down through temperate zones
* {{txil|Equisetum pratense|[[Jakob Friedrich Ehrhart|Ehrh.]]}} – shady horsetail, meadow horsetail, shade horsetail; circumboreal except for tundra down through cool temperate zones
* {{txil|Equisetum sylvaticum|L.}} – wood horsetail; circumboreal down through cool temperate zones, more restricted in east Asia
* {{txil|Equisetum telmateia|Ehrh.}} – great horsetail; Europe to Asia Minor and north Africa. The former North American subspecies ''Equisetum telmateia'' subsp. ''braunii'' (Milde) Hauke is now treated as a separate species {{tx|Equisetum braunii|Milde}}<ref name="Christenhusz2019" /><ref name=powo/>
[[Image:Equisetum ramosissimum, Slavičín, Czech Republic.jpg|thumb|right|''[[Equisetum ramosissimum]]'' in the Czech Republic]]

====Subgenus ''Hippochaete''====
* {{txil|Equisetum giganteum|L.}} – southern giant horsetail or giant horsetail; temperate to tropical South America and Central America north to southern Mexico
* {{txil|Equisetum hyemale|L.}} – rough horsetail; most of non-tropical Old World. The former North American subspecies ''Equisetum hyemale'' subsp. ''affine'' <small>(Engelm.) A.A.Eat.</small> is now treated as a separate species {{tx|Equisetum praealtum|Raf.}}<ref name="Christenhusz2019" /><ref name=powo/>
* {{txil|Equisetum laevigatum|A.Braun}} – smooth horsetail, smooth scouringrush; western 3/4 of North America down into northwestern Mexico; also sometimes known as ''Equisetum kansanum''
* {{txil|Equisetum myriochaetum|[[Diederich Franz Leonhard von Schlechtendal|Schltdl.]] & [[Adelbert von Chamisso|Cham.]]}} – Mexican giant horsetail; from central Mexico south to Peru
* {{txil|Equisetum praealtum|[[Constantine Samuel Rafinesque|Raf.]]}} – scouringrush horsetail, syn. ''E. hyemale'' subsp. ''affine'' <small>(Engelm.) A.A.Eat.</small>; temperate North America
* {{txil|Equisetum ramosissimum|[[René Louiche Desfontaines|Desf.]]}} (including ''[[Equisetum debile|E.&nbsp;debile]]'') – branched horsetail; Asia, Europe, Africa, southwest Pacific islands
* {{txil|Equisetum scirpoides|[[André Michaux|Michx.]]}} – dwarf horsetail, dwarf scouringrush; northern (cool temperate) zones worldwide
* {{txil|Equisetum variegatum|[[Schleich.]] ex [[George Heinrich Weber|Weber]] & [[Charles Mohr (botanist)|Mohr]]}} – variegated horsetail, variegated scouringrush; northern (cool temperate) zones worldwide, except for northeasternmost Asia
* {{txil|Equisetum xylochaetum|[[Georg Heinrich Mettenius|Mett.]]}} – Atacama Desert giant horsetail; southern Peru, northern Chile

====Unplaced to subgenus====
*{{extinct}}''[[Equisetum dimorphum]]'' – [[Early Jurassic]], Argentina
*{{extinct}}''[[Equisetum laterale]] –'' Early to [[Middle Jurassic]], Australia
*{{extinct}}''[[Equisetum thermale]]'' – Middle to [[Late Jurassic]], Argentina
*{{extinct}}''[[Equisetum similkamense]]'' – [[Ypresian]], British Columbia

===Named hybrids===
[[Image:Equisetum x moorei3.JPG|thumb|right|[[Equisetum × moorei|''Equisetum'' × ''moorei'']] (''[[Equisetum hyemale|E.&nbsp;hyemale]]'' × ''[[Equisetum ramosissimum|E.&nbsp;ramosissiumum]]'')]]

====Hybrids between species in subgenus ''Equisetum''====
* [[Equisetum × bowmanii|''Equisetum'' × ''bowmanii'']] {{small|[[Christopher Nigel Page|C.N.Page]]}} (''Equisetum sylvaticum'' × ''Equisetum telmateia'')
* [[Equisetum × dycei|''Equisetum'' × ''dycei'']] {{small|C.N.Page}} (''Equisetum fluviatile'' × ''Equisetum palustre'')
* [[Equisetum × font-queri|''Equisetum'' × ''font-queri'']] {{small|[[Werner Rothmaler|Rothm.]]}} (''Equisetum palustre'' × ''Equisetum telmateia'')
* [[Equisetum × litorale|''Equisetum'' × ''litorale'']] {{small|Kühlew ex [[Franz Josef Ruprecht|Rupr.]]}} (''Equisetum arvense'' × ''Equisetum fluviatile'')
* [[Equisetum × mchaffieae|''Equisetum'' × ''mchaffieae'']] {{small|C.N.Page}} (''Equisetum fluviatile'' × ''Equisetum pratense'')
* [[Equisetum × mildeanum|''Equisetum'' × ''mildeanum'']] {{small|Rothm.}} (''Equisetum pratense'' × ''Equisetum sylvaticum'')
* [[Equisetum × robertsii|''Equisetum'' × ''robertsii'']] {{small|Dines}} (''Equisetum arvense'' × ''Equisetum telmateia'')
* [[Equisetum × rothmaleri|''Equisetum'' × ''rothmaleri'']] {{small|C.N.Page}} (''Equisetum arvense'' × ''Equisetum palustre'')
* [[Equisetum × willmotii|''Equisetum'' × ''willmotii'']] {{small|C.N.Page}} (''Equisetum fluviatile'' × ''Equisetum telmateia'')

====Hybrids between species in subgenus ''Hippochaete''====
* [[Equisetum × ferrissii|''Equisetum'' × ''ferrissii'']] {{small|[[Willard Nelson Clute|Clute]]}} (''Equisetum hyemale'' × ''Equisetum laevigatum'')
* [[Equisetum × moorei|''Equisetum'' × ''moorei'']] {{small|[[Edward Newman (entomologist)|Newman]]}} (''Equisetum hyemale'' × ''Equisetum ramosissimum'')
* [[Equisetum × nelsonii|''Equisetum'' × ''nelsonii'']] {{small|([[Alvah Augustus Eaton|A.A.Eaton]]) Schaffn.}} (''Equisetum laevigatum'' × ''Equisetum variegatum'')
* [[Equisetum × schaffneri|''Equisetum'' × ''schaffneri'']] {{small|Milde}} (''Equisetum giganteum'' × ''Equisetum myriochaetum'')
* [[Equisetum × trachyodon|''Equisetum'' × ''trachyodon'']] {{small|(A.Braun) W.D.J.Koch}} (''Equisetum hyemale'' × ''Equisetum variegatum'')

===Phylogeny===
{| class="wikitable"
|-
! colspan=1 |Christenhusz ''et al.'' 2019<ref name="Christenhusz2019">{{cite journal |last1=Christenhusz |first1=Maarten J M |last2=Bangiolo |first2=Lois |last3=Chase |first3=Mark W |last4=Fay |first4=Michael F |last5=Husby |first5=Chad |last6=Witkus |first6=Marika |last7=Viruel |first7=Juan |title=Phylogenetics, classification and typification of extant horsetails (''Equisetum'', Equisetaceae) |journal=Botanical Journal of the Linnean Society |date=April 2019 |volume=189 |issue=4 |pages=311–352 |doi=10.1093/botlinnean/boz002}}</ref> 
! colspan=1 |Nitta et al. 2022<ref>{{cite journal |last1=Nitta |first1=Joel H. |last2=Schuettpelz |first2=Eric |last3=Ramírez-Barahona |first3=Santiago |last4=Iwasaki |first4=Wataru |display-authors=et al. |year=2022 |title=An Open and Continuously Updated Fern Tree of Life |journal=Frontiers in Plant Science |volume=13 |issue= |page= 909768| doi=10.3389/fpls.2022.909768 |pmid= 36092417|pmc= 9449725|bibcode= 2022FrPS...1309768N|doi-access=free}}</ref> and Fern Tree of life<ref>{{cite web|last1= |first1= |last2= |display-authors=et al. |year=2024 |title=Tree viewer: interactive visualization of FTOL |url=https://fernphy.github.io/viewer.html |version=FTOL v1.7.0 [GenBank release 261] |access-date=1 May 2025}}</ref>
|- 
| style="vertical-align:top|
{{Clade | style=font-size:90%;line-height:80%
|label1=''Equisetum''
|1={{clade
  |1={{clade
  |label1=(''Paramochaete'')
  |1=[[Equisetum bogotense|''E. bogotense'']]
     }}
  |2={{clade
    |label1=(''Equisetum'')
    |1={{clade
      |1={{clade
        |1=[[Equisetum palustre|''E. palustre'']]
        |2=[[Equisetum pratense|''E. pratense'']]
         }}
      |2={{clade
        |1={{clade
          |1=[[Equisetum telmateia|''E. telmateia'']]
          |2=[[Equisetum braunii|''E. braunii'']]
           }}
        |2={{clade
          |1=[[Equisetum sylvaticum|''E. sylvaticum'']]
          |2={{clade
            |1={{clade
              |1=[[Equisetum diffusum|''E. diffusum'']]
              |2=[[Equisetum fluviatile|''E. fluviatile'']]
               }}
            |2=[[Equisetum arvense|''E. arvense'']]
             }}
           }}
         }}
       }}
    |label2=(''Hippochaete'')
    |2={{clade
      |1=[[Equisetum scirpoides|''E. scirpoides'']]
      |2={{clade
        |1=[[Equisetum variegatum|''E. variegatum'']]
        |2={{clade
          |1={{clade
            |1=[[Equisetum ramosissimum|''E. ramosissimum'']]
            |2={{clade
              |1=[[Equisetum hyemale|''E. hyemale'']]
              |2=[[Equisetum praealtum|''E. praealtum'']]
               }}
             }}
          |2={{clade
            |1={{clade
              |1=[[Equisetum laevigatum|''E. laevigatum'']]
              |2=[[Equisetum myriochaetum|''E. myriochaetum'']]
               }}
            |2=[[Equisetum giganteum|''E. giganteum'']]
             }}
           }}
         }}
       }}
     }}
   }}
}}
|
{{Clade | style=font-size:90%;line-height:80%
|label1=''Equisetum''
|1={{clade
  |1={{clade
  |label1=(''Paramochaete'')
  |1=''[[Equisetum bogotense|E. bogotense]]''
     }}
  |2={{clade
    |label1=(''Equisetum'')
    |1={{clade
      |1={{clade
        |1=''[[Equisetum × fontqueri|E. × fontqueri]]''
        |2=''[[Equisetum telmateia|E. telmateia]]''
         }}
      |2={{clade
        |1=''[[Equisetum pratense|E. pratense]]''
        |2={{clade
          |1=''[[Equisetum palustre|E. palustre]]''
          |2={{clade
            |1={{clade
              |1=''[[Equisetum × dycei|E. × dycei]]''
              |2=''[[Equisetum fluviatile|E. fluviatile]]''
               }}
            |2={{clade
              |1=''[[Equisetum arvense|E. arvense]]''
              |2={{clade
                |1=''[[Equisetum × litorale|E. × litorale]]''
                |2=''[[Equisetum sylvaticum|E. sylvaticum]]''
                 }}
               }}
             }}
           }}
         }}
       }}
    |label2=(''Hippochaete'')
    |2={{clade
      |1={{clade
        |1=''[[Equisetum giganteum|E. giganteum]]''
        |2=''[[Equisetum × schaffneri|E. × schaffneri]]''
          }}
      |2={{clade
        |1={{clade
          |1=''[[Equisetum myriochaetum|E. myriochaetum]]''
          |2={{clade
            |1=''[[Equisetum × ferrissii|E. × ferrissii]]''
            |2=''[[Equisetum laevigatum|E. laevigatum]]''
             }}
           }}
        |2={{clade
          |1={{clade
            |1=''[[Equisetum scirpoides|E. scirpoides]]''
            |2=''[[Equisetum ramosissimum|E. ramosissimum]]''
             }}
          |2={{clade
            |1=''[[Equisetum variegatum|E. variegatum]]''
            |2={{clade
              |1=''[[Equisetum hyemale|E. hyemale]]''
              |2=''[[Equisetum × trachyodon|E. × trachyodon]]''
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}
|}