Editing Lycopodiopsida (section)

==Microbial associations==
Lycophytes form associations with microbes such as fungi and bacteria, including [[arbuscular mycorrhiza]]l and [[Endophyte|endophytic]]  associations.

Arbuscular mycorrhizal associations have been characterized in all stages of the lycophyte lifecycle: [[Myco-heterotrophy|mycoheterotrophic]] gametophyte, photosynthetic surface-dwelling gametophyte, young sporophyte, and mature sporophyte.<ref name=WintFrie08/> Arbuscular mycorrhizae have been found in ''[[Selaginella]] spp.'' roots and vesicles.<ref name=LaraVald15/>

During the mycoheterotrophic gametophyte lifecycle stage, lycophytes gain all of their carbon from subterranean [[Glomerales|glomalean]] fungi. In other plant taxa, glomalean networks transfer carbon from neighboring plants to mycoheterotrophic gametophytes. Something similar could be occurring in ''Huperzia hypogeae'' gametophytes which associate with the same glomalean phenotypes as nearby ''Huperzia hypogeae'' sporophytes.<ref name=WintFrie08/>

Fungal endophytes have been found in many species of lycophyte, however the function of these endophytes in host plant biology is not known. Endophytes of other plant taxa perform roles such as improving plant competitive fitness, conferring biotic and abiotic stress tolerance, promoting plant growth through phytohormone production or production of limiting nutrients.<ref name=BacoHint07/> However, some endophytic fungi in lycophytes do produce medically relevant compounds. ''Shiraia'' sp Slf14 is an endophytic fungus present in ''[[Huperzia serrata]]'' that produces [[Huperzine A]], a biomedical compound which has been approved as a drug in China and a dietary supplement in the U.S. to treat Alzheimer's Disease.<ref name=Zhu10/> This fungal endophyte can be cultivated much more easily and on a much larger scale than ''H. serrata'' itself which could increase the availability of Huperzine A as a medicine.