Editing Lycophyte (section)

==Taxonomy==
===Classification===
In the broadest [[Circumscription (taxonomy)|circumscription]] of the lycophytes, the group includes the extinct [[zosterophyll]]s as well as the extant (living) lycophytes and their closest extinct relatives. The names and ranks used for this group vary considerably. Some sources use the names "Lycopodiophyta" or the shorter "Lycophyta" to include zosterophylls as well as extant lycophytes and their closest extinct relatives,<ref name=Dowe17>{{Citation |mode=cs1 |last1=Doweld |first1=Alexander B. |date=2017 |title=(2499) Proposal to conserve the name Zosterophyllaceae against Sciadophytaceae (Fossil Lycopodiophyta: Zosterophyllopsida) |journal=Taxon |volume=66 |issue=1 |pages=207–208 |doi=10.12705/661.27 |doi-access=free }}</ref> while others use these names to exclude zosterophylls.<ref name=TaylTaylKrin09/><ref name=Maus14/> The name "Lycopodiophytina" has also been used in the inclusive sense.<ref name=KenrCran97a/><ref name=KenrCran97b/> English names, such as "lycophyte", "lycopodiophyte" or "lycopod", are similarly ambiguous, and may refer to the broadly defined group or only to the extant lycophytes and their closest extinct relatives.

The consensus classification produced by the [[Pteridophyte Phylogeny Group]] classification in 2016 (PPG&nbsp;I) places all extant (living) lycophytes in the class [[Lycopodiopsida]].<ref name=PPGI/> There are around 1,290 to 1,340 such species.<ref name=CallCook99/><ref name=ChriByng16/><ref name=PPGI/> For more information on the classification of extant lycophytes, see {{section link|Lycopodiopsida|Classification}}.

===Phylogeny===
A major [[cladistics|cladistic]] study of land plants was published in 1997 by Kenrick and Crane.<ref name=KenrCran97/> In 2004, Crane et al. published some simplified [[cladogram]]s, based on a number of figures in Kenrick and Crane (1997). Their cladogram for the lycophytes is reproduced below (with some branches collapsed into 'basal groups' to reduce the size of the diagram).<ref name=CranHereFrii04>{{Citation |mode=cs1 |last1=Crane |first1=P.R. |last2=Herendeen |first2=P. |last3=Friis |first3=E.M. |date=2004 |title=Fossils and plant phylogeny |journal=American Journal of Botany |volume=91 |issue=10 |pages=1683–1699 |doi=10.3732/ajb.91.10.1683 |pmid=21652317 |s2cid=8493380 |name-list-style=amp |doi-access=free }}</ref>
{{clade
  |label1=panlycophyte
  |1={{Clade panlycophyte|lycophyte-label=lycophytes}}
}}
In this view, the "zosterophylls" comprise a [[Paraphyly|paraphyletic]] group, ranging from forms like ''[[Hicklingia]]'', which had bare stems,<ref name=Edwa76/> to forms like ''[[Sawdonia]]'' and ''[[Nothia (plant)|Nothia]]'', whose stems are covered with unvascularized spines or enations.{{sfnp|Taylor|Taylor|Krings|2009|p=253}}<ref name=KerpHassMosb01/> The genus ''[[Renalia]]'' illustrates the problems in classifying early land plants. It has characteristics both of the non-lycophyte [[rhyniophyte]]s – terminal rather than lateral sporangia – and of the zosterophylls – kidney-shaped sporangia opening along the distal margin.{{sfnp|Taylor|Taylor|Krings|2009|p=250}}

A rather different view is presented in a 2013 analysis by Hao and Xue. Their preferred cladogram shows the zosterophylls and associated genera basal to both the lycopodiopsids and the euphyllophytes, so that there is no clade corresponding to the broadly defined group of lycophytes used by other authors.<ref name=HaoXue13/>
{{Barlabel
 |size=6 |at1=3
 |label1=&thinsp;"lycophytes" of other authors
 |bar1=green
 |cladogram={{clade
   |style=line-height:100%
   |label1=tracheophytes
   |1={{clade
      |label1=
      |state1=double
      |1=basal groups
      |2={{clade
         |label1=
         |1={{clade
            |label1=
            |1=''[[Adoketophyton]]''
            |barbegin1=green
            |2=Zosterophyllopsida
            |bar2=green
            }}
         |2={{clade
            |label1=
            |1=Lycopsida|barend1=green
            |2={{clade
               |label1=
               |state1=double
               |1=basal groups
               |2=''[[Yunia]]'', ''[[Dibracophyton]]''
               |3=euphyllophytes
            }}
         }}
      }}
   }}
}}
}}

Some extinct orders of lycophytes fall into the same group as the extant orders. Different sources use varying numbers and names of the extinct orders. The following phylogram shows a likely relationship between some of the proposed Lycopodiopsida orders.{{citation needed|date=October 2019}}
{{clade
|style=line-height:100%
|label1=Lycopodiopsida
|1={{clade
   |label1=
   |1={{clade
      |label1=
      |1=[[Lycopodiales]]
      |2=†[[Drepanophycales]]
      }}
   |2={{clade
      |label1=
      |1=[[Selaginellales]]
      |2={{clade
         |label1=
         |1=†[[Lepidodendrales]]
         |2={{clade
            |label1=
            |1=†[[Pleuromeia]]les
            |2=[[Isoetales]]
            }}
         }}
      }}
   }}
}}