South African Journal of Botany 157 (2023) 372 379 Contents lists available at ScienceDirect South African Journal of Botany journal homepage: www.elsevier.com/locate/sajb Ligule and contraligule in Cyperaceae: A systematic review Lucas Alves-dos-Santosa,*, Ana Paula do Nascimento Pratab, Bruno Edson-Chavesc,
da Cruz Martinsa, Delmira da Costa Silvad, Lailson Ce
sar Andrade Gomesb, Daniel Jose a
via de Albuquerque Melo-de-Pinnaa Vitor Fernando Pereira de Jesus , Gladys Fla a ~o Paulo, Rua do Mata ~o 277, Cidade Universita
ria, Sa ~o Paulo, SP 05508-090, Brazil Department of Botany, University of Sa
rias (CECA), Federal University of Alagoas, Rio Largo, AL 7100-000, Brazil Centro de Ci^encias Agra ~o, Ci^encias e Letras de Iguatu,
, Av. Da
rio Rabelo s/n, Iguatu, CE 63500‑000, Brazil
University of Ceara Faculdade de Educaç a d Campus Soane Nazare
de Andrade, University of Santa Cruz, Rodovia Jorge Amado, Ilhe
us, BA 45662-900, Brazil b c A R T I C L E I N F O Article History: Received 24 November 2022 Revised 31 March 2023 Accepted 4 April 2023 Available online xxx Edited by: Prof G.V. Cron Keywords: Dorsal ligule Eligulate Leaf sheath Membranous ligule Poales A B S T R A C T 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. © 2023 SAAB. Published by Elsevier B.V. All rights reserved. 1. Introduction Cyperaceae is a widely diverse family of herbaceous plants comprising about 5700 species distributed in two subfamilies, 24 tribes, and 95 genera (Larridon et al., 2021). Although it has a cosmopolitan distribution, this family shows great diversity in the tropics (Simpson and Inglis, 2001), with 30 genera and 647 species recognized in Brazil, of which 196 are endemic (Schneider et al., 2022). The wide geographic distribution reflects an equally rich diversity in the natural history of the family, including annual, perennial, wind- and insectpollinated plants, C3 and C4 organization, and aquatic and terrestrial habits (Goetghebeur, 1998; Naczi and Ford, 2008; Larridon et al., 2021; Schneider et al., 2022). The leaf in Cyperaceae presents the typical morphology of monocotyledons, with leaf blade and sheath, which in this family is generally closed (Goetghebeur, 1998). The morphological diversity of the leaves in Cyperaceae includes structures such as the ligule and contraligule, which are present in some genera. * Corresponding author. E-mail address: lucas.alvees1235@usp.br (L. Alves-dos-Santos). https://doi.org/10.1016/j.sajb.2023.04.011 0254-6299/© 2023 SAAB. Published by Elsevier B.V. All rights reserved. The ligule is an appendage, membranous or ciliated, located in the line dividing the leaf sheath and leaf blade (Font Quer, 2001; Melode-Pinna and Cruz, 2020; Edson-Chaves et al., 2022), that when well distinguished, is useful to clearly delimit these two regions of the leaf (Tsiantis and Langdale, 1998). Although described as absent in Cyperaceae (Ravi and Mohanan, 2002; Pantoja, 2016) or rare (Metcalfe, 1971; Judd et al., 2009), Mohlenbrock (2005) describes the ligule as "mostly present" in the family. In Poales, the ligule is present in Joinvilleaceae, Juncaceae, Poaceae, Xyridaceae, and Cyperaceae (EdsonChaves et al., 2022). In Poaceae, this structure has received great attention and has been explored by anatomical (Metcalfe, 1960; Chaffey, 1994; Szabo et al., 2006), evolutionary (Edson-Chaves et al., 2022), and ontogenetic (Edson-Chaves, 2022) approaches. The contraligule is a more or less triangular ligule-like structure located at the top of the sheath opposite the leaf blade (Dahlgren et al., 1985; Mayfield, 2021). Although also considered rare in Cyperaceae (Goetghebeur, 1998), this structure has great diagnostic importance for the genera in which it occurs, and shows some variability within the family. For example, in Carex L., the contraligule may be individualized or fused with the ligule to form a single tubular L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 structure (Cusset and Hoa Tran Thi Tuyet, 1965). These authors named "ligule sensu stricto" the structure only in the adaxial region of the leaf and "ligule sensu lato" the whole structure that includes the contraligule and the s.s. ligule. This classification is derived from the close association between these two leaf structures, since both ligule and contraligule constitute a single structure in some genera. The presence of the ligule was investigated by Camelbeke and Goetghebeur (1999) who provided a global analysis of this structure in the family. However, since then, significant taxonomic changes have occurred, notably in the delimitations of subfamilies and genera. Therefore, a revision that considers the most recent taxonomic delimitations is necessary, as already done in Poaceae (Edson-Chaves et al., 2022). This study explored the distribution of the ligule and contraligule in different groups of Cyperaceae, taking into account the most up-to-date group classification and generating data that will be useful in future research on the evolution of characters in the family, as well as signaling important groups for developmental studies. We observed all genera of Cyperaceae. Except for cases in which only one specimen was available, at least two specimens were observed for each species. In total, we evaluated the presence or absence of ligule and contraligule of 1150 species, which represents approximately 20% of the total diversity of the family. All species analyzed, as well as some of the exsiccatae observed, are presented in Appendix B. 3. Results and discussion We evaluated the presence of the ligule in all genera (Table 1) of both subfamilies. Of the 24 tribes, seven (29,17%) were eligulate and 17 (70,83%) had at least one species with a ligule (Fig. 1). Information regarding the presence or absence of the ligule on different tribes of Cyperaceae obtained in this review was mapped based on the phylogenetic relationships proposed by Larridon et al. (2021). We found that the ligule was completely absent in Mapanioideae, present only in Cyperoideae (Fig. 2). In this subfamily, the eligulate tribes are distributed across the phylogeny, with a large clade primarily ligulate (Scirpo Caricoid clade) and five eligulate tribes. Seven tribes have all species with a ligule (Calliscirpeae, Dulichieae, Fuireneae, Khaosokieae, Schoenoplecteae, Sumatroscirpeae, and Trichophoreae), which represents about 1,8% of all family diversity. Of these, five are monogeneric, with the exception of Dulichieae (three genera) and Schoenoplecteae (two genera). Also, seven tribes are completely eligulate (Bisboeckelereae, Bolboschoeneae, Carpheae, Cladieae, Chrysitricheae, Hypolytreae, and Rhynchosporeae). They represent approximately 11,4% of the Cyperaceae, and are composed mostly of Rhynchospora Vahl (c. 400 spp.). The ten remaining tribes (Abildgaardieae, Cariceae, Cryptangieae, Cypereae, Eleocharideae, Pseudoschoeneae, Scirpeae, Schoeneae, Sclerieae, and Trilepideae) have species both with and without a ligule and in these groups this structure may have taxonomic value at generic or specific level. The biggest genera in which the ligule was both present and absent were Carex (c. 2000 spp.), Cyperus L. (c. 960 spp.), and Fimbristylis Vahl (c. 320 spp.). The ligule is rare in Cryptangieae, given that it was present in only one monotypic genus (Koyamaea WW.Thomas & Davidse). We classified the ligule as unusual in Abildgaardieae and Cypereae, given that, for Abildgaardieae, the ligule was only present in some species of Bulbostylis and Fimbristylis and in some genera with few species, and in Cypereae the ligule was present in only four genera (Table 2). In Cariceae, Pseudoschoeneae, Scirpeae, Schoeneae, and Trilepideae, presence of the ligule was the majority. Specifically in Carex, Camelbeke & Goetghebeur (1999) classified the entire genus as ligulate, but Bruhl (1995) described the ligule as usually present but absent in aphyllous species. We found one species in which the ligule appeared absent: Carex fraseriana Ker Gawl. (Holm, 1896; Roalson et al., 2021). Several authors consider the leaf to be sheathless in C. fraseriana (Holm, 1896; Carter, 2005), which explains the absence of a ligule, although the absence of a well-marked central vein has made other authors hypothesize that, in fact, the leaf of this species is a bladeless expanded sheath (e.g., Camelbeke and Goetghebeur, 1999). 2. Methodology 2.1. Bibliographic research strategy and inclusion criterion The bibliographic research process was done in three stages: In the first stage, searches were made in four databases, PubMed (https://pubmed.ncbi.nlm.nih.gov/), Science Direct (https://www.sci encedirect.com/), Scopus (https://www.scopus.com/) and Web of Science (https://www.webofscience.com/), using the keywords "ligule AND Cyperaceae" and "contraligule AND Cyperaceae" for English and "lígula AND Cyperaceae" and "contralígula AND Cyperaceae" for Portuguese, from which 111 references were obtained. Of these, 20 were excluded because they represented repetitions. Of the resulting 91 articles, 37 were classified as useful for this review according to the following inclusion criterion: information about the presence or absence of ligule or contraligule in Cyperaceae at any taxonomic level. The second stage consisted of searching for articles in a fifth database, Google Scholar (https://scholar.google.com.br/), using the keyword "contraligule AND Cyperaceae", as a way to supplement missing information left by the first step regarding the contraligule. Of the 75 articles retrieved, 14 were excluded because they represented repetitions (they appeared more than once in the database search or had been included in the previous step). Of the 61 resulting articles, 57 were considered useful for this review according to the inclusion criterion. Finally, to compensate for the lack of information regarding the ligule in 21 genera, original articles describing the genera, as well as some traditional references, were added. The family circumscription was based on Larridon et al. (2021). A total of 102 articles were included, as listed in Appendix A. 2.2. Herbaria consultation We conducted an extensive review of Cyperaceae genera to investigate the presence of the contraligule. Two herbaria were visited, ~o MAC (Environment Institute, IMA-AL) and SPF (University of Sa Paulo, USP), and 6 virtual databases were consulted: Australasian Virtual Herbarium (https://avh.ala.org.au/), BM (The Natural History https://data.nhm.ac.uk/dataset/collection-specimens), Museum, Reflora (https://reflora.jbrj.gov.br/reflora/herbarioVirtual/ConsultaPu blicoHVUC/ConsultaPublicoHVUC.do), K (Royal Botanic Gardens, http://apps.kew.org/herbcat/gotoHomePage.do), NY (The New York Botanical Garden, http://sweetgum.nybg.org/science/vh/) and P
um National d’Histoire Naturelle, https://science.mnhn.fr/insti (Muse tution/mnhn/item/search). Herbaria codes follow the Index Herbariorum (https://sweetgum.nybg.org/science/ih/). Table 1 Results obtained and the total corresponding to each taxonomic level according to Larridon et al. (2021) and Larridon (2022). Percentage of data in relation to the total of each taxonomic level. 373 Taxonomic level Scope of results Scope percentual Subfamily Tribe Genus Species 2/2 24/24 95/95 1150/5687 100% 100% 100% 20,22% L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 Fig. 1. Percentage of Cyperaceae tribes and genera that are ligulate (green) and eligulate (red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 2. Mapping results for presence (black), absence (white) and both presence and absence (black and white) of ligule and contraligule following the phylogeny proposed by Larridon et al. (2021). The subfamily Mapanioideae is represented in blue and Cyperoideae in orange.
pez, 2012; ArdisBruhl, 1995; Larridon, 2006; Larridon et al., 2008; Lo sone, 2018; Silva, 2021). A curious feature of Bulbostylis is the pres
pez, 2012) a feature ence of trichomes on the top of the sheath (Lo that can easily be mistaken for a ciliate ligule. Distinguishing between a ligule and these long trichomes at the apex of the sheath can be aided by the position of the structures, but this is not always sufficient: in some species, the long trichomes start from both the sides of the sheath and the membranous ligule itself (see excellent illustra
pez, 2012). However, there is no doubt about the presence tions in Lo of a ligule in Bulbostylis, either membranous or ciliate. Given the universal presence of the ligule in seven tribes and in most species of another five tribes, we estimate that the ligule is present in approximately 43% of Cyperaceae species, a number primarily including species of Carex, a genus that solely represents about 35% of ligulate species (these values are estimations, since we have not examined every species of the family). Carex is present in a primarily ligulate clade (Scirpo-Caricoid Clade) that includes seven tribes and 14 genera (Fig. 2). Only one of these 14 genera did not have species with a ligule, Phylloscirpus C.B.Clarke, with three species. High conservation of the ligule is a curious characteristic of this clade, and the eligulate species probably represent reversions from a ligulate ancestor. We found conflicting information regarding the presence of a ligule in Anthelepis R.L.Barrett, K.L.Wilson, & J.J.Bruhl (Schoeneae). In describing the genus, Barrett et al. (2019) described all four species as “apparently lacking a ligule” (p. 278). Larridon et al. (2021), however, describes the subtribe Anthelepidinae (which has only the genus Anthelepis) as “ligulate”. Indeed, all four Anthelepis species have a distinct ligule (Barrett, pers. com.). There are three morphological types of ligules in Cyperaceae reported in the literature: membranous, ciliate, and firm; the first two have been extensively reported by several authors (e.g., Kukkonen and Toivonen, 1988; Camelbeke et al., 1997; Elliott et al., 2019; Ribeiro et al., 2021). The membranous ligule was reported in Actinoscirpus, Carex, Cyperus, Fuirena, Ptilothrix, Schoenoplectiella, and Schoenus. In Carex, the A curious aspect is the presence of a ligule in Eleocharis, Schoenoplectiella Lye and Schoenoplectus (Rchb.) Palla. These genera have species with lamina absent or reduced to a setiform structure called
lez-Elizondo and Peterson, 1997; Hinchliff et al., "mucro" (Gonza 2010). In Schoenoplectiella, the ligule is present and can be easily identified in species with lamina (either well developed or reduced to a mucro), but in species without lamina, the presence of a ligule can be obscure, since the ligule is a leaf structure located between the sheath and lamina. As discussed by Hayasaka (2012), in Schoenoplectus and Schoenoplectiella without a lamina (either well developed or reduced to a mucro), the apex of the sheath has a hyaline ligulate margin, something that the author does not consider a ligule, although he interprets it as homologous to the ligule found in species with lamina. For Eleocharis, the genus is usually considered as eligulate, an expected condition given the absence of lamina in most species. However, we found species in which the line between the sheath and the reduced lamina (mucro) presented a ligulate structure (Fig. 3). Camelbeke and Goetghebeur (1999) and Goetghebeur (1998) both classified the genus as wholly eligulate, but Bruhl (1995) recognized the presence of the ligule in the genus and signaled its presence in two species, E. congesta and E. dietrichiana (both not available for consultation). The ligulate structure that we found in some species (Fig. 3) was unusual in this genus and is considered a ligule by Bruhl (1995), but not by others. We followed Bruhl (1995) in Table 2 and classified the genus as mostly eligulate, but it seems to us that this is a topic for further discussion, and that considering Eleocharis as eligulate may not be the most appropriate. Examining the three major genera of Abildgaardieae, Kral (1971) reports the presence of a ligule in some species of Fimbristylis but points out that "neither Abildgaardia nor Bulbostylis produces a comparable structure” (p. 62). In agreement with this, Goetghebeur (1998) and Camelbeke and Goetghebeur (1999) also classified the latter two genera as eligulate. In fact, there is no ligule in Abildgaardia
zy et al., 2022). It is now clear that some Bulbostylis species (Mesterha have a ciliate ligule, as reported by some authors (Tucker, 1987; 374 L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 Table 2 (Continued) Table 2 Presence or absence of ligule and contraligule on the genera of Cyperaceae. “+” means presence and “-” means absence. When both the character states are present, the first sign represents the majority of the species (e.g., “-/+” means mostly eligulate but with at least one ligulate species). Subfamily/tribe MAPANIOIDEAE Chrysitricheae Hypolytreae CYPEROIDEAE Trilepideae Genus Ligule Contraligule Dulichium Pers. Blysmopsis Oteng-Yeb. Blysmus Panz. ex Schult. + + + + + Khaosokieae Khaosokia D.A.Simpson + Calliscirpeae Calliscirpus C.N.Gilmour, J.R.Starr & Naczi + Scirpeae Amphiscirpus Oteng-Yeb. Zameioscirpus Dhooge & Goetgh.
v.-Bourret, DonaRhodoscirpus Le dío & J.R.Starr Phylloscirpus C.B.Clarke Eriophorum L. Scirpus Tourn. ex L. + + + + + Trichophoreae Trichophorum Pers + Sumatroscirpeae Sumatroscirpus Oteng-Yeb. + Cariceae Carex L. +/- Eleocharideae Eleocharis R.Br -/+ Abildgaardieae Nelmesia Van der Veken Bulbostylis Kunth Zulustylis Muasya Trichoschoenus J.Raynal Actinoschoenus Benth. Arthrostylis R.Br. Trachystylis S.T.Blake Scleroschoenus K.L.Wilson, J.J. Bruhl & R.L.Barrett Abildgaardia Vahl Fimbristylis Vahl Hypolytrum Pers. Paramapania Uittien Scirpodendron Zipp. ex Kurz Mapania Aubl. Microdracoides Hua Afrotrilepis (Gilly) J.Raynal Trilepis Nees Coleochloa Gilly Cladium P.Browne Bisboeckelereae Bisboeckelera Kuntze Calyptrocarya Nees Becquerelia Brongn. Diplacrum R.Br. Sclerieae Scleria P.J.Bergius Carpheae Trianoptiles Fenzl ex Endl. Carpha Banks & Sol. ex R.Br. Cryptangieae Rhynchosporeae Genus Dulichieae Contraligule Diplasia Pers. Exocarya Benth. Capitularina J.Kern Lepironia Pers. Chrysitrix L. Chorizandra R.Br. Cladieae Schoeneae Ligule Subfamily/tribe + + -* + + + -/+ -/+ +/- Koyamaea W.W.Thomas & Davidse Didymiandrum Gilly Krenakia S.M.Costa Cryptangium Schrad. ex Nees Exochogyne C.B.Clarke Lagenocarpus Nees Cephalocarpus Nees + + Anthelepis R.L.Barrett, K.L.Wilson & J.J.Bruhl Oreobolus R.Br. Chamaedendron Larridon Capeobolus Browning Cyathocoma Nees Costularia C.B.Clarke Ptilothrix K.L.Wilson Mesomelaena Nees Cyathochaeta Nees Gahnia J.R.Forst. & G.Forst. Reedia F.Muell. Gymnoschoenus Nees Evandra R.Br. Caustis R.Br. Machaerina Vahl. Neesenbeckia Levyns Netrostylis R.L.Barrett, J.J.Bruhl & K.L.Wilson Lepidosperma Labill. Chaetospora R.Br. Tricostularia Nees Ammothryon R.L.Barrett, K.L.Wilson & J.J.Bruhl Xyroschoenus Larridon Morelotia Gaudich. Tetraria P.Beauv. Schoenus L. + Rhynchospora Vahl +/+ + +/-/+ -/+ Fuireneae Fuirena Rottb. + Schoenoplecteae Actinoscirpus (Ohwi) R.W.Haines & Lye Schoenoplectus (Rchb.) Palla + + Pseudoschoenus (C.B.Clarke) Oteng-Yeb. Schoenoplectiella Lye +/- + + + + + Incertae Cedis + + + + Bolboschoenus (Asch.) Palla Cypereae Erioscirpus Palla
g. Scirpoides Se Afroscirpoides García-Madr. & Muasya Dracoscirpoides Muasya Hellmuthia Steud. Isolepis R.Br. Ficinia Schrad. Cyperus L. -/+ -/+ + Bolboschoeneae Pseudoschoeneae -/+ -/+ + -/+ + +/-/+ -/+ Rhynchocladium T.Koyama * We did not find a reference describing the absence of contraligule on this genus, but, given that Microdracoides has open sheaths, it is coherent to suppose that there is no contraligule. + + ligule may be limited to the adaxial region of the leaf (ligule s.s. sensu Cusset and Hoa Tran Thi Tuyet, 1965) or have a unique structure on the apex of the sheath, covering the shoot (ligule s.l. sensu Cusset and Hoa Tran Thi Tuyet, 1965) of variable sizes (Cusset and Hoa Tran Thi Tuyet, 1965; Kukkonen and Toivonen, 1988). According to Zhang et al. (2004), in some cases, such as in Ptilothrix and Carpha, the membranous ligule is a diagnostic character for delimitation of the genera and is absent in Carpha. -/+ + -/+ (continued) 375 L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 Fig. 3. Stereoscopic and scanning electron microscopy analysis, with detail on the ligulate structure, of: (a-b) Eleocharis elegans; (c-d) E. montana; (e-f) E. geniculata; and (g-h) E. nudipes. All species, except E. geniculata, present a ligulate structure (indicated by an arrow) between the mucro, M, and the sheath, S. a, c and e scale bars = 1 mm; b, f and h scale bars = 100 mm; d and g bars = 200 mm; inset scale bars on b, d and h = 40 mm. provide data on the degree of homology between these structures in the family. The ciliate ligule, cited in Amphiscirpus and Scleria, is the second most commonly described type in the family. Amphiscirpus has only one species, Amphiscirpus nevadens (S. Watson) Oteng-Yeb. In Scleria, Camelbeke and Goetghebeur (1999) described five species (S. amazonica, S. scabra, S. secans, S. tenacissima, and S. vaginata) as having a ciliate ligule. According to the same authors, the ciliate ligules in Scleria may vary in shape (horizontal or “V-shaped”), density, and trichome color (yellow, dark brown, etc.). We found a contraligule in 12 tribes (Table 1), and only Fuireneae with only one genus, Fuirena Rottb., and Blysmopsis Oteng-Yeb. (Dulichieae) had all species with a contraligule, which was fused with a ligule and formed a single membranous structure (this also happens in Carex, as discussed below). This seems to be present in all species of the genus, and the distinction between the ligule and contraligule In Cyperus, a mostly eligulate genus, two species (C. prophyllatus and C. blepharoleptos) present a ligule with a membranous base and a ciliate apex, described as a membranous ligule (Ribeiro et al., 2021), which is in agreement with Bruhl (1995), who also stated that the ligule may be present in this genus, and Camelbeke and Goetghebeur (1999), who described C. blepharoleptos (as Oxycaryum cubense (Poepp. & Kunth) Palla) as ligulate. This morphologic pattern is referred to by Edson-Chaves et al. (2022), in Poaceae, as being “membranous ciliate”. The “firm” type is only mentioned in two articles that revise the genus Schoenus (Elliott and Muasya, 2018; Elliott et al., 2019). These authors describe that ligule may be of the type membranaceous or “firm”, and that the ligules may vary in size (Elliott et al., 2019). The fact that the “firm” type is not mentioned by any other author in Cyperaceae suggests that this type is a variety of the membranous type. However, only a detailed study of its ontogeny may 376 L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 so it is present in genera with closed sheaths (Afrotrilepis (Gilly) J. Raynal and Trilepis Nees) and absent in the last two that have open sheaths (Coleochloa Gilly and Microdracoides Hua). According to Vitta (2002), distinguishing characters in Trilepis are limited, and only the size and thickness of the contraligule and the length of the frutifications seem to be useful in separating species. The open sheath in Coleochloa (Kativu, 1994) and Microdracoides (Chermezon, 1933) is an unusual characteristic of Cyperaceae, and the absence of a contraligule is expected, as also occurs in Poaceae, a large family with open sheaths and without any comparable structure to that of the Cyperaceae contraligule. In Poaceae, the contraligule is also used by some authors to designate a structure between the sheath and leaf blade opposite to the ventral ligule (e.g., Dahlgren et al., 1985; Sanchez-Ken and D
avila, 1995; Thompson, 2022). This structure in this family is also referred to as “outer ligule”, “external ligule” and “dorsal ligule”. It is necessary to emphasize that the term is used in Poaceae and Cyperaceae, but it refers to different structures. Bruhl (1995) cites the nonequivalence of the term in the two families, given that these structures are not the same, and Longhi-Wagner et al. (2001), seeking to avoid misunderstandings, recommends the use of the term “external ligule” in Poaceae. Given the above, we agree with Longhi-Wagner et al. (2001) and Edson-Chaves et al. (2022) that the term “contraligule” must be applied only to Cyperaceae. Goetghebeur (1998) cites that a contraligule in Cyperaceae is “rarely developed”, but is “diagnostically valuable on many species of Scleria”. The same author described the contraligule of Afrotrilepis, Calyptrocarya, Cephalocarpus, Koyamaea, Trilepis, and Lagenocarpus as triangular and the contraligule of Scleria as “often present, sometimes as a large outgrowth”, referring to the membranous appendage present in some species. The contraligule is of particular taxonomic significance in Scleria, given that it is a good character for distinguishing Scleria from Bisboeckelereae (Goetghebeur, 1998) and Scleria species. For example, a membranous appendage on the top of the contraligule is useful in distinguishing S. secans (with a membranous appendage) from S. skutchii (Strong, 1994) and S. distans (contraligule unappendaged) from S. leptostachya (Souza et al., 2019) and helps in the identification of S. violacea, in combination with a ciliate ligule and an ovoid nutlet (Schneider and Gil, 2020). As with the ligule, the concept of a contraligule is not always clear. The apex of the sheath opposite the blade in Cyperaceae may (or may not) have an extension, and this extension can be very evident or very subtle. Therefore, the presence or not of a contraligule may be subject to different interpretations in cases where it is not very evident. A more careful look at the concept of this structure is indeed still needed. is unclear. In other genera, however, the ligule and contraligule appear to be two distinct structures (e.g., Scleria). Ontogenetic studies may clarify the relationship between these two structures in Blysmopsis, Fuirena and Carex. The other 11 tribes (Bisboeckelereae, Bolboschoeneae, Cariceae, Cryptangieae, Cypereae, Dulichieae, Rhynchosporeae, Scirpeae, Schoeneae, Sclerieae and Trilepideae) have both species with and without a contraligule. The contraligule is present in the majority in Cryptangieae and Sclerieae. On the other tribes, the number of species with or without a contraligule was similar (Trilepideae) or the species without a contraligule were the majority (the remaining eight tribes). On the tribes where the contraligule is the majority (Cryptangieae and Sclerieae), this structure is normally well developed. In Cryptangieae, a tribe with seven genera, the contraligule is typically triangular or deltoid, and has a ciliate apex (Alves-dos-Santos, pers.obs.) and the contraligule was completely absent in only one genus (Didymiandrum Gilly, with one species) (Goetghebeur, 1998; Camelbeke and Goetghebeur, 1999). No other genus has morphological diversity of the contraligule comparable to Scleria (the only genus included in Sclerieae). This structure is not universal in this genus but is present in most species. It is possible to find deltoid, lanceolate, or triangular contraligules, with the apex more or less acute and, most notably, with or without a large membranous appendage (Affonso et al., 2015; Schneider and Gil, 2020). We believe that aspects that allow such structural diversity in the leaf are a good topic for future research in this genus. On the remaining eight tribes where the contraligule is “rare” (Bisboeckelereae, Bolboschoeneae, Cariceae, Cypereae, Dulichieae, Rhynchosporeae, Scirpeae and Schoeneae), we have different scenarios. Except for Dulichieae and Schoeneae, the contraligule was present in only one genus in each tribe. For Schoeneae, we found a contraligule in only two species: Tetraria mlanjensis J.Raynal and Ammothryon grandiflorum (Nees ex Lehm.) R.L.Barrett, K.L.Wilson & J. J.Bruhl. Indeed, when describing T. mlanjensis, Raynal (1972) mentioned the presence of a contraligule (“antiligule arrondie”; Raynal, 1972). In Bisboeckelereae, the contraligule is present only in two species of one genus: Calyptrocarya bicolor (H.Pfeiff.) T. Koyama and C. poeppigiana Kunth (Appendix B). The presence of a contraligule in this genus is consistent with the findings of Bruhl (1995). Some species of Bolboschoenus (Asch.) Palla (the only genus in Bolboschoeneae) have an elevated sheath apex that can be considered a contraligule, but this structure is never very developed in the genus. This is in concordance with Bruhl (1995), who described the sheath apex of the genus as “slightly Inverted U-shaped to ’truncate’”. In Cariceae, the contraligule is uncommon but very developed in some species. As mentioned, the ligule and the contraligule, both membranous, can form a single, tubular structure, generally referred to as “ligule l.s.” (Cusset and Hoa Tran Thi Tuyet, 1965). A contraligule is typically absent in all Cypereae, but we found this structure in one species: Cyperus mundii (Nees) Kunth. This species is easily distinguished by its stoloniferous habit with well-developed sheaths and laminae. In Dulichieae, the contraligule is only present in Dulichium arundinaceum (L.) Britton, as also reported by Bruhl (1995), and in Blysmopsis rufa (Table 2), a species whose ligular morphology is similar to what is seen in Fuirena and Carex. The contraligule is rare in the Rhynchosporeae and Scirpeae. For the former, the contraligule seems to be present in some species, with an emphasis on Rhynchospora contraligularis W. W. Thomas (Thomas, 2020). For the latter, we found only one species, Scirpus diffusus Schuyler. This does not agree with Bruhl (1995), who described the apex of the sheath as truncate for this genus, but Schuyler (1966) described the sheath apex of this species as “truncato ad convexo” (p. 140). It seems that this species may indeed have a contraligule, but it is an exception to the genus. Trilepideae is a tribe with four genera and 16 species (Larridon et al., 2021). In this tribe, the contraligule is correlated with the sheath, 4. Conclusion and future perspectives Ligule and contraligule are important structures in the taxonomy of several genera in Cyperaceae, notably Carex, Schoenus and Scleria. Numerically, 70.83% of the tribes and 44.21% of the genera have at least one species with ligule, which shows the comprehensiveness of this structure in the family. The contraligule is present in 20 genera, and our results corroborate Goetghebeur’s (1998) description of the contraligule in Cyperaceae as "rare", since it is universally present only in two genera. However, its low occurrence does not agree with the structural diversity in Scleria and its close association with the ligule in Carex and Fuirena. Further studies that explore these the ligule and contraligule, especially in tribes classified as eligulate and without a contraligule, should aim to reinforce the presence or absence of these structures. To us, it is clear that the classification of Cyperaceae as eligulate is not empirically justified since this structure is widely present in the 377 L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 genera of the family. Future research should focus on the primary homology (sensu Pinna, 1991) of these characters in Poales.
lez-Elizondo, M.S., Peterson, P.M., 1997. A classification of and key to the supraGonza specific taxa in Eleocharis (Cyperaceae). Taxon 46 (3), 433–449. https://doi.org/ 10.2307/1224386. Hayasaka, E., 2012. Delineation of Schoenoplectiella lye (Cyperaceae), a genus newly segregated from Schoenoplectus (Rchb.) Palla. J. Japn. Bot. 87 (3), 169–186. Hinchliff, C.E., Lliully A, A.E., Carey, T., Roalson, E.H., 2010. The origins of Eleocharis (Cyperaceae) and the status of Websteria, Egleria, and Chillania. Taxon 59 (3), 709– 719. https://doi.org/10.1002/tax.593004. Holm, T., 1896. Studies in the Cyperaceae; III, Carex fraseri Andrews, a morphological and anatomical study. Am. J. Sci. 4 (14), 121–128. Judd, W.S., Campbell, C.S., Kellogg, E.A., Stevens, P.F., Donoghue, M.J., 2009. Sistem
atica
tico. Artmed Editora, Porto Alegre. Vegetal: Um Enfoque Filogene Kativu, S., 1994. Notes on Coleochloa Gilly (Cyperaceae) in the Flora Zambesiaca area. Kirkia 33–37. Kral, R., 1971. A treatment of Abildgaardia, Bulbostylis and Fimbristylis (Cyperaceae) for North America. SIDA. Contribut. Bot. 4 (2), 57–227. Kukkonen, I., Toivonen, H., 1988. Taxonomy of wetland carices. Aquat. Bot. 30 (1 2), 5– 22. https://doi.org/10.1016/0304-3770(88)90003-4. Larridon, I., 2006. M.Sc. Thesis. Ghent University, p. 185. Larridon, I., 2022. A linear classification of Cyperaceae. Kew Bull. 77 (1), 309–315. Larridon, I., Reynders, M., Goetghebeur, P., 2008. Novelties in Nemum (Cyperaceae). Belgian J. Bot. 157–177.
veille
-Bourret, E., Barrett, R.L., Starr, J.R., Muasya, A.M., Larridon, I., Zuntini, A.R., Le Villaverde, T., Bauters, K., Brewer, G.E., Bruhl, J.J., Costa, S.M., Elliott, T.L., Epitawalage, N., Escudero, M., Fairlie, I., Goetghebeur, P., Hipp, A.L.,
nez-Mejías, P., Kikuchi, I.A.B.S., Lucen ~ o, M., M
arquez-Corro, J.I., Jime Martín-Bravo, S., Maurin, O., Pokorny, L., Roalson, E.H., Semmouri, I., Simpson, D.A., Spalink, D., Thomas, W.W., Wilson, K.L., Xanthos, M., Forest, F., Baker, W.J., 2021. A new classification of Cyperaceae (Poales) supported by phylogenomic data. J. Syst. Evol. 59 (4), 852–895. https://doi.org/10.1111/jse.12757. Longhi-Wagner, H.M., Bittrich, V., Wanderley, M.G.L., Shepherd, G.J., 2001. POACEAE. ^mica do In: Wanderley, M.G.L., Shepherd, G.J., Giulietti, A.M. (Eds.), Flora Faneroga Estado de S~ao Paulo (Vol. 1).
pez, M.G., 2012. Citología, Morfología y Taxonomía Del Ge
nero Bulbostylis (CyperaLo
rica Austral. National University of the Northeast, p. 233. http:// ceae) Para Ame repositorio.unne.edu.ar/handle/123456789/474. Mayfield, E., 2021. Illustrated Plant Glossary. CSIRO, Melbourne. Melo-de-pinna, G.F.A., Cruz, R., 2020. Leaf development in vascular plants. In: Demarco, D. (Ed.), Plant Ontogeny: studies, Analyses and Evolutionary Implications. Nova Science Publishers, Inc., New York.
zy, A., Browning, J., Verloove, F., 2022. Cyperaceae of tropical West Africa. Mesterha Meise Botanic Garden, Meise. Metcalfe, C.R., 1960. Anatomy of the Monocotyledons. I. Gramineae. Clarendon Press, Oxford. Metcalfe, C.R., 1971. Anatomy of the Monocotyledons. V. Cyperaceae. Clarendon Press, Oxford. Mohlenbrock, R.H., 2005. Cyperaceae: Sedges (Vol. 1). SIU Press, Illinois. Naczi, R.F.C., Ford, B.A. (Eds.), 2008. Sedges: uses, diversity, and Systematics of the Cyperaceae (Vol. 108). Missouri Botanical Garden Press, St. Louis. Pantoja, S., 2016. Sistem
atica vegetal: Primeiros Passos. Technical Books, Rio de Janeiro. Pinna, M.C.C., 1991. Concepts and tests of homology in the cladistic paradigm. Cladistics 7 (4), 367–394. https://doi.org/10.1111/j.1096-0031.1991.tb00045.x. Ravi, N., Mohanan, N., 2002. Common Tropical and Sub-Tropical Sedges and Grasses. Science Publishers.
rologiques: 18. un Tetraria nouveau du Malawi. Adansonia Raynal, J., 1972. Notes cype 12 (2), 213–215.
nez-Mejías, P., Hipp, A.L., Benítez-Benítez, C., Bruederle, L.P., Roalson, E.H., Jime Chung, K.S., Escudero, M., Ford, B.A., Ford, K., Gebauer, S., Gehrke, B., Hahn, M.,
veille
-Bourret, É., Hayat, M.Q., Hoffmann, M.H., Jin, X.F., Kim, S., Larridon, I., Le ~ o, M., Maguilla, E., M
arquez-Corro, J.I., Martín-Bravo, S., Masaki, T., Lu, Y.F., Lucen Míguez, M., Naczi, R.F.C., Reznicek, A.A., Spalink, D., Starr, J.R., Uzma, Villaverde, T., Waterway, M.J., Wilson, K.L., Zhang, S.R., 2021. A framework infrageneric classification of Carex (Cyperaceae) and its organizing principles. J. Syst. Evol. 59, 726–762. https://doi.org/10.1111/jse.12722. Ribeiro, A.R.D.O., Pereira-Silva, L., Vieira, J.P.S., Larridon, I., Ribeiro, V.S., Felitto, G.,
jo, A., Alves, M., 2021. Cyperus prophyllatus: an endanSiqueira, G.S., Alves-Arau gered aquatic new species of Cyperus L. (Cyperaceae) with a exceptional spikelet disarticulation pattern among about 950 species, including molecular phylogenetic, anatomical and (micro) morphological data. PLoS ONE 16 (6), 1–23. https:// doi.org/10.1371/journal.pone.0249737.
vila, P., 1995. Aristida tuitensis (Poaceae: aristideae), a New Species Sanchez-Ken, J.G., Da from El Tuito, Jalisco, Mexico. Novon 190–192. https://doi.org/10.2307/3392245. Schneider, L.J.C., Gil, A.D.S.B., 2020. Diversity of Scleria (Cyperaceae) in Amazonian rest
sia 71. https://doi.org/10.1590/2175inga in Par
a state, Brazil. Rodrigue 7860202071101. Schneider, L.J.C., Pereira-Silva, L., Thomas, W.W., Matzenauer, W., Hefler, S.M.,
nez-Mejías, P., Weber, P., Nunes, C.S., Maciel-Silva, J.F., Prata, A.P.N., Jime Silva Filho, P.J.S., Costa, S.M., Soares Neto, R.L., Alves, K.N.L., Gil, A.S.B., Trevisan, R.,
pez, M.G., Hall, C.F., Fernandes-Ju
nior, A.J., Vitta, F.A., Orsolano, G.N., Lo Wanderley, M.G.L., 2022. Cyperaceae in Flora e Funga do Brasil. Jardim Bot^anico do Rio de Janeiro. https://floradobrasil.jbrj.gov.br/FB100. Schuyler, A.E., 1966. A new species of Scirpus in California. Brittonia 140–142. https:// doi.org/10.2307/2805197. Silva, J.F.M., 2021. M.Sc. Thesis. Rural Federal University of Amazonia, p. 157. Simpson, D.A., Inglis, C.A., 2001. Cyperaceae of economic, ethnobotanical and horticultural importance: a checklist. Kew Bull. 257–360. https://doi.org/10.2307/ 4110962. Financial support ~o de Amparo a  This study was financially supported by Fundaç a ~o Paulo (FAPESP Research Grant 2019/ Pesquisa do Estado de Sa 15,195 8 to GFAMP, technical training Grant 2021/08,063 8, 2021/ 08,221 2 and 2021/08,062 1 to DJCM, LAS and VFPJ, respectively)
gico and Conselho Nacional de Desenvolvimento Científico e Tecnolo (CNPq Productiviy Grant 303962/2019 4 to GFAMP). Declaration of Competing Interest The authors declare that they have no competing interests. All authors have signed the Declaration of Competing Interest statement. Acknowledgements The authors thank the herbarium (SPF) and Plant Anatomy Labo~o Paulo (USP) and the herbarium of Instiratory at the University of Sa tuto do Meio Ambiente do Estado de Alagoas (IMA) for technical assistance. We thank Dr. Russell Barrett (NSW) for his help with two Australian genera. Finally, we also thank the editors of South African Journal of Botany and anonymous reviewers for the suggested improvements. Supplementary materials Supplementary material associated with this article can be found in the online version at doi:10.1016/j.sajb.2023.04.011. References Affonso, R., Zanin, A., Brummitt, N.A., 2015. Diversity of Scleria (Cyperaceae) in Santa
sia 66, 353–367. Catarina, Brazil. Rodrigue Ardissone, R.E., 2018. Ph.D. Thesis. Federal University of Rio Grande do Sul, p. 117. Barrett, R.L., Wilson, K.L., Bruhl, J.J., 2019. Anthelepis, a new genus for four mainly tropical species of Cyperaceae from Australia, New Caledonia and South-East Asia. Aust. Syst. Bot. 32 (4), 269–289. https://doi.org/10.1071/SB18047. Bruhl, J.J., 1995. Sedge genera of the world: relationships and a new classification of the Cyperaceae. Aust. Syst. Bot. 8 (2), 125–305. https://doi.org/10.1071/SB9950125. Camelbeke, K., Strong, M.T., Goetghebeur, P., 1997. Scleria amazonica, a new species of Scleria section Scleria (Cyperaceae) from Venezuela. Novon 7 (2), 98–101. http:// hdl.handle.net/1854/LU-185013. Camelbeke, K., Goetghebeur, P., 1999. The ligule, a new diagnostic character in Scleria (Cyperaceae). Syst. Geogr. Plants 68 (1 2), 73–84. https://doi.org/10.2307/ 3668592. Carter, R., 2005. An introduction to the sedges of Georgia. Tipularia 20, 15–44. Chaffey, N.J., 1994. Structure and function of the membranous grass ligule: a comparative study. Bot. J. Linn. Soc. 116 (1), 53–69. https://doi.org/10.1111/j.10958339.1994.tb00421.x. Chermezon, H., 1933. Observations sur le genre Microdracoides. Bull. Soc. Bot. France 80 (1), 90–97.
ge
tative des Carex. Bull. Soc. Cusset, G., Hoa Tran Thi Tuyet, M., 1965. La ligule de la feuille ve Bot. France 112 (1 2), 42–54. https://doi.org/10.1080/00378941.1965.10838443. Dahlgren, R.M., Clifford, H.T., Yeo, P.F., 1985. The Families of the monocotyledons: structure, evolution, and Taxonomy. Springer Science & Business Media, New York. Edson-Chaves, B., 2022. Ph.D. Thesis. University of S~ao Paulo, p. 139. https://doi.org/ 10.11606/T.41.2022.tde-11072022-154500. Edson-Chaves, B., Silva, O.L.M., Clark, L.G., Melo-de-Pinna, G.F.A., 2022. The ligule in Poaceae: a historical and evolutionary review. Bot. Rev. 1–40. https://doi.org/ 10.1007/s12229-022-09285-3. Elliott, T.L., Muasya, A.M., 2018. A taxonomic revision of Schoenus compar - Schoenus pictus and allies (Cyperaceae, tribe Schoeneae) with three new species described from South Africa. S. Afr. J. Bot. 114, 303–315. https://doi.org/10.1016/j. sajb.2017.11.020. Elliott, T.L., Barrett, R.L., Muasya, A.M., 2019. A taxonomic revision of Schoenus cuspidatus and allies (Cyperaceae, tribe Schoeneae) part 1. S. Afr. J. Bot. 121, 519–535. https://doi.org/10.1016/j.sajb.2018.11.021.
nica, 2nd ed . Península, Barcelona. Font Quer, P., 2001. Diccionario De Bota Goetghebeur, P., 1998. Cyperaceae. In: Kubitzki, K. (Ed.), Flowering Plants¢ Monocotyledons. Springer, Berlin, pp. 141–190. 378 L. Alves-dos-Santos, A.P.d.N. Prata, B. Edson-Chaves et al. South African Journal of Botany 157 (2023) 372 379 Souza, T.D., Liesenfeld, V., Trevisan, R., Silva, S.M., 2019. Synopsis of Cyperaceae in the
State Park, Paran
a, Brazil. Rodrigue
sia 70. https://doi.org/ grasslands of Guartela 10.1590/2175-7860201970008. Strong, M.T., 1994. Two new species of Scleria section Scleria (Cyperaceae) from the Neotropics. Novon 296–302. https://doi.org/10.2307/3391661. Szabo, Z.K., Papp, M., Daroczi, L., 2006. Ligule anatomy and morphology of five Poa species. Acta Biol. Cracoviens. Ser. Bot. 48 (2), 83–88. Thomas, W.W., 2020. Two new species of Rhynchospora (Cyperaceae) from Bahia, Brazil, and new combinations in Rhynchospora section Pleurostachys. Brittonia 72 (3), 273–281. https://doi.org/10.1007/s12228-020-09621-0. Thompson, E.J., 2022. Simonachne, a new genus for Australia segregated from Ancistrachne sl (Poaceae: panicoideae: paniceae) and a new subtribe Cleistochloinae. Aust. Syst. Bot. 35 (1), 19–62. https://doi.org/10.1071/SB20024. Tsiantis, M., Langdale, J.A., 1998. The formation of leaves. Curr. Opin. Plant Biol. 1 (1), 43–48. https://doi.org/10.1016/S1369-5266(98)80126-X. Tucker, G.C., 1987. The genera of Cyperaceae in the southeastern United States. J. Arnold Arboretum 68 (4), 361–445. Vitta, F.A., 2002. Trilepis tenuis (Cyperaceae: trilepideae), a new species from Rio de Janeiro, southeastern Brazil. Brittonia 54 (2), 120–123. 10.1663/0007-196X(2002) 054[0120:TTCTAN]2.0.CO;2. Zhang, X., Marchant, A., Wilson, K.L., Bruhl, J.J., 2004. Phylogenetic relationships of Carpha and its relatives (Schoeneae, Cyperaceae) inferred from chloroplast trnL intron and trnL trnF intergenic spacer sequences. Mol. Phylogenet. Evol. 31 (2), 647–657. https://doi.org/10.1016/j.ympev.2003. 09.004. 379