Ligule and contraligule in Cyperaceae: A systematic review

• Published in: South African journal of botany 2023-06, Vol.157, p.372-379
• Main Authors: Alves-dos-Santos, Lucas, Prata, Ana Paula do Nascimento, Edson-Chaves, Bruno, Martins, Daniel José da Cruz, Silva, Delmira da Costa, Gomes, Lailson César Andrade, Jesus, Vitor Fernando Pereira de, Melo-de-Pinna, Gladys Flávia de Albuquerque
• Format: Article
• Language: English
• Subjects: Cyperaceae; Dorsal ligule; Eligulate; family; leaf blade; Leaf sheath; Membranous ligule; Poales; species; surveys; systematic review
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2023.04.011

•Cyperaceae is the third largest monocot family, with a global distribution.•The ligule is a structure with a considerable taxonomic value, notably in Poaceae.•17 out of 24 tribes and 42 out of 95 genera have at least one ligulate species.•The contraligule is a unique structure in Cyperaceae.•Further studies will clarify aspects of ventral and dorsal ligules and contraligules. Cyperaceae is the second largest family of Poales, with approximately 5700 species distributed across 95 genera. The occurrence of the ligule, a membranous or ciliate structure located on the adaxial surface between the leaf sheath and leaf blade, is a characteristic that requires investigation, since in the few studies done on this structure in Cyperaceae, it is clear that there are genera that have a ligule. In this family, the presence of a contraligule is also described, a rare ligule-like structure that is more or less triangular on top of the sheath in the region opposite to the leaf blade. Thus, this study was carried out with the objective of understanding the presence and diversity of the ligule and contraligule in Cyperaceae, investigating whether they are uncommon structures or if they have received little importance in the literature. For this, a systematic survey was conducted in five databases, and 1/5 of the species in the family were investigated in herbaria, either in person or virtually. Studies that contained information regarding the absence or presence of ligules or contraligules in Cyperaceae at any taxonomic level were considered. Of the 24 Cyperaceae tribes, 17 had at least one species with a ligule. Of the 95 genera investigated, 42 had at least one species with a ligule. Contraligule was observed in 12 tribes and 20 genera. We noted that these two structures are absent in most species but still play important roles in the taxonomy of the groups in which they are present. Cyperaceae has many ligulate representatives, which disagrees with the classification of the family as eligulate.