Editing Isoetes (section)

=== Evolution ===
[[File:Isoetites sp UWBM37862 WaG 1996 img1.png|thumb|right|Undescribed ''[[Isoetites]]'' fossil<br/>[[Klondike Mountain Formation]]]]
The earliest fossil that has been assigned to the genus is {{extinct}}''[[Isoetes beestonii]]'' from the latest Permian<ref name="Retallack2013">{{cite journal |last1=Retallack |first1=G.J. |year=2013 |title=Permian and Triassic greenhouse crises |journal=Gondwana Research |volume=24 |issue=1 |pages=90–103 |doi=10.1016/j.gr.2012.03.003|bibcode=2013GondR..24...90R }}</ref> of New South Wales, Australia, around 252 million years ago.<ref name="Retallack1997">{{Cite journal |last=Retallack |first=G.J. |year=1997 |title=Earliest Triassic origin of ''Isoetes'' and quillwort evolutionary radiation |journal=Journal of Paleontology |volume=71 |issue=3 |pages=500–521 |doi=10.1017/S0022336000039524 |bibcode=1997JPal...71..500R |s2cid=140566050 |issn=0022-3360 |url=https://www.cambridge.org/core/product/identifier/S0022336000039524/type/journal_article |language=en }}</ref> However, the relationships of pre-Jurassic isoetaleans to modern ''Isotetes'' have been regarded as unclear by other authors.<ref name="Wood2020" /> ''Isoetites rolandii'' from the Late Jurassic of North America has been described as the "earliest clear example of a isoetalean lycopsid containing all the major features uniting modern ''Isoetes",'' including the loss of the elongated stem and vegetative leaves. Based on this, it has been stated that "the overall morphology of ''Isoetes'' appears to have persisted virtually unchanged since at least the Jurassic".''<ref name="Wood2020" />'' The timing of the origin of the [[crown group]] is uncertain. Wood ''et al'' (2020) asserted there to be no morphological features that define the major clades within ''Isoetes,'' and no fossils are known that can be definitively assigned to the crown group.''<ref name="Wood2020" />'' While Wood ''et al.'' suggested a young origin dating to the early [[Cenozoic]] based on [[molecular clock]] estimates''<ref name="Wood2020" />'', the results were questioned by Wikström ''et al.'' (2023) who regarded the molecular clock as providing no firm evidence for the origin time of the genus, which could date to the [[Mesozoic]] or even the late [[Paleozoic]], depending on the [[Molecular clock#Calibration|calibration]] method used.<ref name="Wikström-2023" />