Editing Lycopodiopsida (section)

==Evolution==
[[File:Lepidodendron.png|thumb|upright|Artist's impression of a ''Lepidodendron'']]
[[File:LepidodendronOhio.jpg|thumb|External impression of ''[[Lepidodendron]]'' from the [[Pennsylvanian (geology)|Upper Carboniferous]] of [[Ohio]]]]
[[File:Lycopod axis.jpg|thumb|Axis (branch) from ''[[Archaeosigillaria]]'' or related lycopod from the Middle [[Devonian]] of [[Wisconsin]]]]
The Lycopodiopsida are distinguished from other vascular plants by the possession of microphylls and by their sporangia, which are lateral as opposed to terminal and which open (dehisce) transversely rather than longitudinally. In some groups, the sporangia are borne on sporophylls that are clustered into strobili. Phylogenetic analysis shows the group branching off at the base of the evolution of vascular plants and they have a long evolutionary history. [[Fossil]]s are abundant worldwide, especially in [[Coal|coal deposits]]. Fossils that can be ascribed to the Lycopodiopsida first appear in the [[Silurian]] period, along with a number of other vascular plants. The Silurian ''[[Baragwanathia|Baragwanathia longifolia]]'' is one of the earliest identifiable species. ''[[Lycopodolica]]'' is another Silurian genus which appears to be an early member of this group.<ref name=RaymGensStei06/> The group evolved roots independently from the rest of the vascular plants.<ref name=HethDola18/><ref name=HethDola19/>

From the [[Devonian]] onwards, some species grew large and tree-like. Devonian fossil lycopsids from [[Svalbard]], growing in equatorial regions, raise the possibility that they drew down enough carbon dioxide to change the Earth's climate significantly.<ref>{{Cite web|url=https://www.cardiff.ac.uk/news/view/163982-tropical-fossil-forests-unearthed-in-arctic-norway|title=Tropical fossil forests unearthed in Arctic Norway}}</ref> During the [[Carboniferous]], [[Lepidodendrales|tree-like plants]] (such as ''[[Lepidodendron]]'', ''[[Sigillaria]]'', and other extinct genera of the order ''Lepidodendrales'') formed huge forests that dominated the landscape. Unlike modern trees, leaves grew out of the entire surface of the trunk and branches, but fell off as the plant grew, leaving only a small cluster of leaves at the top. The lycopsids had distinctive features such as ''Lepidodendron'' lycophytes, which were marked with diamond-shaped scars where they once had leaves. Quillworts (order Isoetales) and ''Selaginella'' are considered their closest extant relatives and share some unusual features with these [[fossil]] lycopods, including the development of both bark, [[cambium]] and [[wood]], a modified shoot system acting as roots, bipolar and [[secondary growth]], and an upright stance.<ref name=Awas09/><ref name=StewRoth93/> The remains of ''Lepidodendron'' lycopods formed many fossil [[coal]] deposits. In [[Fossil Grove]], Victoria Park, Glasgow, Scotland, fossilized lycophytes can be found in [[sandstone]].

The Lycopodiopsida had their maximum diversity in the [[Pennsylvanian (geology)|Pennsylvanian]] (Upper Carboniferous), particularly tree-like ''Lepidodendron'' and ''[[Sigillaria]]'' that dominated tropical wetlands. The complex ecology of these tropical rainforests [[Carboniferous rainforest collapse|collapsed]] during the Middle Pennsylvanian due to a change in climate.<ref name=SahnBentFalc10/> In [[Euramerica]], tree-like species apparently became extinct in the Late Pennsylvanian, as a result of a transition to a much drier climate, giving way to [[conifer]]s, [[fern]]s and [[Equisetidae|horsetails]]. In [[Cathaysia]] (now South China), tree-like species survived into the [[Permian]]. Nevertheless, lycopodiopsids are rare in the [[Lopingian]] (latest Permian), but regained dominance in the [[Induan]] (earliest Triassic), particularly ''[[Pleuromeia]]''. After the worldwide [[Permian–Triassic extinction event]], members of this group pioneered the repopulation of habitats as opportunistic plants. The heterogeneity of the terrestrial plant communities increased markedly during the Middle Triassic when plant groups like horsetails, ferns, [[pteridosperm]]s, [[cycad]]s, [[Ginkgoales|ginkgos]] and conifers resurfaced and diversified quickly.<ref name=MoisVoig13/>