This page is about the various taxonomic groupings of related organisms; it should not be confused with the ecological grouping of unrelated plant taxa in phytosociology.
The term is often used for a group that authors are studying in further detail in order to refine the complex taxonomy. For example, a molecular phylogenetics study of the Aerides–Vanda Alliance (Orchidaceae: Epidendroideae) confirmed that the group is monophyletic, and clarified which species belong in each of the 14 genera.[3] In other orchid groups, the various alliances that have been defined do not correspond well to clades.[4]
Historically, some 19th century botanical authors used alliance to denote groups that would now be considered orders.[5] This usage is now obsolete, and the ICN (Article 17.2) specifies that such taxa are treated as orders.[citation needed]
^Emshwiller, E. (2002), "Ploidy Levels among Species in the 'Oxalis tuberosa Alliance' as Inferred by Flow Cytometry", Annals of Botany, 89 (6): 741–753, doi:10.1093/aob/mcf135, PMC4233841, PMID12102530[dead link]
^Zhai, J.-W.; Zhang, G.-Q.; Li, L.; Wang, M.; Chen, L.-J.; Chung, S.-W.; et al. (2014), "A new phylogenetic analysis sheds new light on the relationships in the Calanthe alliance (Orchidaceae) in China", Molecular Phylogenetics and Evolution, 77 (Complete): 216–222, doi:10.1016/j.ympev.2014.04.005, PMID24747128
^Salazar, G.A.; Chase, M.W.; Soto Arenas, M.A.; Ingrouille, M. (2003), "Phylogenetics of Cranichideae with emphasis on Spiranthinae (Orchidaceae, Orchidoideae): evidence from plastid and nuclear DNA sequences", American Journal of Botany, 90 (5): 777–795, doi:10.3732/ajb.90.5.777, PMID21659175
