Introduction

To support curation in herbaria opting to organise their collections in accordance with phylogenetic relationships among genera, and to provide an easy-to-use summary for a variety of audiences, a linear sequence of Cyperaceae is published here. Linear sequences reflect the order of names attached to the tips of a phylogenetic tree, after the branches in the tree have been ordered according to some projection method (Chatrou et al. 2018). The methodology for translating tree-like relationships into a linear sequence published by Haston et al. (2007) is followed. Linear sequences are available for vascular plants (Wearn et al. 2013), lycophytes and ferns (Christenhusz et al. 2011a), extant gymnosperms (Christenhusz et al. 2011b), angiosperms (Haston et al. 2007, 2009), and several plant families including Annonaceae (Chatrou et al. 2018) and Fabaceae (Lewis et al. 2013).

Following Chatrou et al. (2018), the following steps were taken to assemble the phylogenetic tree underpinning the linear sequence, and to translate the tree into the sequence: (1) Largely based on the results of Larridon et al. (2021a), a summary tree showing relationships of all genera of Cyperaceae was assembled. Details are given below in the section ‘Cyperaceae classification’. (2) Clade size was defined in terms of number of species, with species numbers for all genera based on Larridon et al. (2021a). (3) Nodes of the phylogenetic tree were rotated so that clades with fewer species were placed before clades with more species following Haston et al. (2007). This clade size criterion was applied to all nodes in the tree, starting from the root node (Fig. 1). As a result, the names along the tips from top to bottom represent the linear sequence.

Fig. 1
figure 1

Summary tree underlying the linear sequence of Cyperaceae genera (A: Chrysitricheae to Schoeneae; B: Rhynchosporeae to Cypereae). Topology based on Larridon et al. (2021a), except for the position of Capeobolus within Oreobolineae based on Larridon et al. (2018a), the approximate position of Didymiandrum within Cryptangieae based on Costa et al. (2021), the position of Ammothryon within Tricostulariinae based on Barrett et al. (2021a), and the position of Blysmopsis and Blysmus in Dulichieae based on Semmouri et al. (2019). The approximate positions of Nelmesia and Trichoschoenus are based on (embryo) morphology data and biogeography (Larridon et al. 2021b). The number of species for each genus is indicated. Bars on the right indicate tribal classification

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Cyperaceae classification

A recent paper provided a new classification of Cyperaceae at tribal, subtribal and generic level (Larridon et al. 2021a) based on targeted sequencing data obtained with the Angiosperms353 probe kit (Johnson et al. 2019) to build a well-supported phylogenetic framework for the family. Only eight genera could not be placed in the phylogenomic study, for five of which (Ammothryon R.L.Barrett, K.L.Wilson & J.J.Bruhl, Blysmopsis Oteng-Yeb., Blysmus Panz. ex Schult., Capeobolus Browning, Didymiandrum Gilly) their phylogenetic placement is known based on previous Sanger sequencing-based studies (e.g. Larridon et al. 2018a; Semmouri et al. 2019; Barrett et al. 2021a; Costa et al. 2021). For Nelmesia Van der Veken and Trichoschoenus J.Raynal, both monotypic genera only known from a single collection, placement was decided based on (embryo) morphology and biogeography (Larridon et al. 2021a, b). Rhynchocladium T.Koyama is the only genus that remains unplaced.

Since the Cyperaceae classification of Goetghebeur (1998), the circumscription of several genera has been altered, mostly in tribes Abildgaardieae, Cariceae, Cypereae, Eleocharideae, Schoeneae and Scirpeae, and in the Fuireneae s.l. Grade (tribes Pseudoschoeneae and Schoenoplecteae).

In tribe Abildgaardieae, the circumscription of the genera Bulbostylis Kunth and Fimbristylis Vahl has changed. Recently, the small mainland African genus Nemum Desv. was synonymised with Bulbostylis (Roalson et al. 2019a; Larridon et al. 2019), and the Australian monotypic genus Crosslandia W.Fitzg. was sunk into Fimbristylis (Roalson et al. 2019b). Furthermore, a new genus Zulustylis Muasya was published for two species previously placed in Fimbristylis (Muasya et al. 2020). Lastly, a new genus Scleroschoenus K.L.Wilson, J.J.Bruhl & R.L.Barrett was published to encompass Australian species previously placed in Actinoschoenus Benth., but clearly forming their own lineage related to two other Australian genera, Arthrostylis R.Br. and Trachystylis S.T.Blake (Larridon et al. 2021b).

The Global Carex Group (2015) re-circumscribed the megadiverse genus Carex (c. 2000 species) as a monophyletic group. To do so, they synonymised the genera Cymophyllus Mack., Kobresia Willd., Schoenoxiphium Nees, and Uncinia Pers. with Carex.

The biggest taxonomic changes at generic level occurred in tribe Cypereae. After the now monotypic tribe Cariceae, it is the second most species-rich tribe in Cyperaceae with well over 1100 species (Larridon et al. 2021a). Before the molecular era, the tribe Cypereae was circumscribed based on embryo morphology; all species included in this tribe have either a Cyperus type embryo or similar Ficinia type embryo (Goetghebeur 1998; Semmouri et al. 2019). Studies have shown that embryos provide some of the best morphological characters to delimit Cyperaceae groups that agree with molecular phylogenetic results (Semmouri et al. 2019). Two clades are distinguished in tribe Cypereae, the Ficinia Clade or subtribe Ficiniinae and the Cyperus Clade or subtribe Cyperinae (Larridon et al. 2021a). Ficiniinae species are predominantly characterised by having spikelets with spirally arranged glumes. In contrast, species of the Cyperinae usually have spikelets with distichous or two-ranked glumes. Besides Cyperus sensu stricto, 13 segregate genera as circumscribed by the classification of Goetghebeur (1998) belong to Cyperinae (Larridon et al. 2021a). Molecular phylogenetic studies revealed that these segregate genera are all nested within Cyperus sensu stricto and that several of them do not form natural groups (Larridon et al. 2011a, 2013; Bauters et al. 2014). As a result, their species were recently transferred to Cyperus (Larridon et al. 2011b, 2014; Bauters et al. 2014; Pereira-Silva et al. 2020).

In tribe Eleocharideae, the segregate genera Chillania Roiv., Egleria L.T.Eiten and Websteria S.H.Wright have been sunk into the large and widely distributed wetland genus Eleocharis R.Br. (Hinchliff et al. 2010).

Recently, efforts have been made to realign the taxonomy of some of the larger tribe Schoeneae genera, i.e. Costularia C.B.Clarke, Epischoenus C.B.Clarke, Schoenus L., Tetraria P.Beauv. and Tricostularia Nees, to make them monophyletic. This resulted in the description of a range of new genera (Ammothryon R.L.Barrett, K.L.Wilson & J.J.Bruhl, Anthelepis R.L.Barrett, K.L.Wilson & J.J.Bruhl, Chamaedendron Larridon, Netrostylis R.L.Barrett, J.J.Bruhl & K.L.Wilson, Xyroschoenus (Kük.) Larridon; Barrett et al. 2019, 2021a, b; Larridon et al. 2018a), recircumscription of existing genera (Costularia, Morelotia Gaudich., Schoenus and Tetraria; Elliott & Muasya 2017; Larridon et al. 2018b; Barrett et al. 2021a), and reinstatement of a previously published genus (Chaetospora R.Br.; Barrett et al. 2020).

In tribe Scirpeae, the Linnean genus Scirpus L. was very heterogenous (Starr et al. 2021). Based on molecular phylogenetic and embryo morphology data, a series of new genera were described (e.g. Zameioscirpus Dhooge & Goetgh., Dhooge et al. 2003; Dracoscirpoides Muasya, Muasya et al. 2012; Calliscirpus C.N.Gilmour, J.R.Starr & Naczi, Gilmour et al. 2013; Afroscirpoides García-Madr. & Muasya, García-Madrid et al. 2015; Rhodoscirpus Lév.-Bourret, Donadío & J.R.Starr, Léveillé-Bourret et al. 2015).

Further changes at generic level occurred, with recircumscription of some genera including publication of the new genus Krenakia S.M.Costa in tribe Cryptangieae (Costa et al. 2021), the synonymisation of Pleurostachys Brongn. with Rhynchospora Vahl in Rhynchosporeae (Thomas 2020), and the synonymisation of Principina Uittien with Hypolytrum Pers. (Mesterházy et al. 2021).

Besides changes to generic limits, tribal limits have also changed with the erection or reinstatement of a number of small or monogeneric tribes representing well-supported lineages that had previously been placed in Schoeneae s.l. (tribes Carpheae and Cladieae; Semmouri et al. 2019), Scirpeae s.l. (tribes Calliscirpeae, Khaosokieae, Sumatroscirpeae and Trichophoreae; Léveillé-Bourret et al. 2018; Léveillé-Bourret & Starr 2019) and Fuireneae s.l. (Bolboschoeneae, Pseudoschoeneae, Schoenoplecteae; Starr et al. 2021). Conversely, the monotypic tribe Koyamaeae was sunk into Cryptangieae (Larridon et al. 2021a). The efforts to recircumscribe tribe Fuireneae as a monophyletic group also resulted in a recircumscription of the genera Schoenoplectus (Rchb.) Palla and Schoenoplectiella Lye (Starr et al. 2021). A detailed study of tribe Trichophoreae resulted in lumping Cypringlea M.T.Strong and Oreobolopsis T.Koyama & Guagl. into Trichophorum Pers. (Léveillé-Bourret et al. 2020). To summarise, while the previous complete classification at tribal and generic level (Goetghebeur 1998) recognised four subfamilies, 14 tribes and 104 genera, following the current taxonomy (Larridon et al. 2021a), two subfamilies, 24 tribes, 10 subtribes and 95 genera are now accepted in Cyperaceae. Currently, c. 5687 species are recognised in the family.

Linear sequence of Cyperaceae

Accepted names are listed in bold. Commonly used or recently subsumed synonyms are listed.

CYPERACEAE JUSS.

M apanioideae C.B.C larke

Chrysitricheae Nees

Diplasia Pers. (1 sp.)

Exocarya Benth. (1 sp.)

Capitularina J.Kern (1 sp.)

Lepironia Pers. (1 sp.)

Chrysitrix L. (4 spp.)

Chorizandra R.Br. (6 spp).

Hypolytreae Nees ex Wight & Arn.

Hypolytrum Pers. (63 spp.)

Principina Uittien

Paramapania Uittien (7 spp.)

Scirpodendron Zipp. ex Kurz (2 spp.).

Mapania Aubl. (100 spp.)

Cyperoideae Beilschm.

Trilepideae Goetgh.

Microdracoides Hua (1 sp.)

Afrotrilepis (Gilly) J.Raynal (2 spp.)

Trilepis Nees (5 spp.)

Coleochloa Gilly (8 spp.)

Cladieae Nees

Cladium P.Browne (3 spp.)

Bisboeckelereae Pax

Bisboeckelera Kuntze (4 spp.)

Calyptrocarya Nees (8 spp.)

Becquerelia Brongn. (6 spp.)

Diplacrum R.Br. (10 spp.)

Sclerieae Wight & Arn.

Scleria P.J.Bergius (258 spp.)

Carpheae Semmouri & Larridon

Trianoptiles Fenzl ex Endl. (3 spp.)

Carpha Banks & Sol. ex R.Br. (15 spp.)

Asterochaete Nees

Cryptangieae Benth.

Koyamaea W.W.Thomas & Davidse (1 sp.)

Didymiandrum Gilly (1 sp.)

Krenakia S.M.Costa (10 spp.)

Cryptangium Schrad. ex Nees (1 sp.)

Exochogyne C.B.Clarke (2 spp.)

Lagenocarpus Nees (15 spp.)

Cephalocarpus Nees (20 spp.)

Everardia Ridl.

Schoeneae Dumort.

Anthelepidinae R.L.Barrett,

Anthelepis R.L.Barrett, K.L.Wilson & J.J.Bruhl (4 spp.)

Oreobolinae R.L.Barrett

Oreobolus R.Br. (17 spp.)

Schoenoides Seberg

Chamaedendron Larridon (5 spp.)

Capeobolus Browning (1 sp.)

Cyathocoma Nees (3 spp.)

Costularia C.B.Clarke (15 spp.)

Gahniinae Pax

Ptilothrix K.L.Wilson (1 sp.)

Mesomelaena Nees (5 spp.)

Cyathochaeta Nees (5 spp., plus several undescribed)

Gahnia J.R.Forst. & G.Forst. (41 spp., plus several undescribed)

Gymnoschoeninae R.L.Barrett

Reedia F.Muell. (1 sp.)

Gymnoschoenus Nees (2 spp.)

Caustiinae R.L.Barrett

Evandra R.Br. (2 spp.)

Caustis R.Br. (7 spp.)

unplaced species Tetraria borneensis J.Kern

Lepidospermatinae R.L.Barrett

Machaerina Vahl. (55 spp.)

Baumea Gaudich.

Neesenbeckia Levyns (1 sp.)

Netrostylis R.L.Barrett, J.J.Bruhl & K.L.Wilson (11 spp.)

Lepidosperma Labill. (80 spp., plus many yet to be described species)

Tricostulariinae R.L.Barrett

Chaetospora R.Br. (3 spp.)

Tricostularia Nees (11 spp.)

Ammothryon R.L.Barrett, K.L.Wilson & J.J.Bruhl (1 sp.)

Xyroschoenus Larridon (1 sp.)

Morelotia Gaudich. (6 spp.)

Tetrariopsis C.B.Clarke

Tetraria P.Beauv. (39 spp.)

Schoeninae Fenzl

Schoenus L. (149 spp.)

Rhynchosporeae Nees

Rhynchospora Vahl (399 spp.)

Dichromena Michx.

Pleurostachys Brongn.

Dulichieae W.Schultze-Motel

Dulichium Pers. (1 sp.)

Blysmopsis Oteng-Yeb. (1 sp.)

Blysmus Panz. ex Schult. (3 spp.)

Khaosokieae Lév.-Bourret & J.R.Starr

Khaosokia D.A.Simpson (1 sp.)

Calliscirpeae Lév.-Bourret & J.R.Starr

Calliscirpus C.N.Gilmour, J.R.Starr & Naczi (2 spp.)

Scirpeae T.Lestib.

Amphiscirpus Oteng-Yeb. (1 sp.)

Zameioscirpus Dhooge & Goetgh. (3 spp.)

Rhodoscirpus Lév.-Bourret, Donadío & J.R.Starr (1 sp.)

Phylloscirpus C.B.Clarke (3 spp.)

Eriophorum L. (18 spp.)

Scirpus Tourn. ex L. (47 spp.)

Trichophoreae Lév.-Bourret & J.R.Starr

Trichophorum Pers. (19 spp.)

Cypringlea M.T.Strong

Oreobolopsis T.Koyama & Guagl.

Sumatroscirpeae Lév.-Bourret & J.R.Starr

Sumatroscirpus Oteng-Yeb. (4 spp.).

Cariceae Dumort.

Carex L. (2003 spp.)

Cymophyllus Mack.

Kobresia Willd.

Schoenoxiphium Nees

Uncinia Pers.

Eleocharideae Goetgh.

Eleocharis R.Br. (c. 302 spp.)

Chillania Roiv.

Egleria L.T.Eiten

Websteria S.H.Wright

Abildgaardieae Lye

Nelmesia Van der Veken (1 sp.)

Bulbostylis Kunth (227 spp.)

Nemum Desv.

Zulustylis Muasya (2 spp.)

Trichoschoenus J.Raynal (1 sp.)

Actinoschoenus Benth. (2 spp.)

Arthrostylis R.Br. (2 spp.)

Trachystylis S.T.Blake (1 sp.)

Scleroschoenus K.L.Wilson, J.J.Bruhl & R.L.Barrett (6 spp.)

Abildgaardia Vahl (9 spp.)

Fimbristylis Vahl (320 spp.)

Crosslandia W.Fitzg.

Bolboschoeneae (Tatanov) J.R.Starr

Bolboschoenus (Asch.) Palla (15 spp.).

Fuireneae Rchb. ex Fenzl

Fuirena Rottb. (55 spp.)

Schoenoplecteae Lye

Actinoscirpus (Ohwi) R.W.Haines & Lye (1 sp.)

Schoenoplectus (Rchb.) Palla (16 spp.)

Pseudoschoeneae J.R.Starr

Pseudoschoenus (C.B.Clarke) Oteng-Yeb. (1 sp.)

Schoenoplectiella Lye (63 spp.)

Cypereae Dumort.

Ficiniinae Fenzl

Erioscirpus (2 spp.) Palla

Scirpoides Ség. (4 spp.)

Afroscirpoides García-Madr. & Muasya (1 sp.)

Dracoscirpoides Muasya (3 spp.)

Hellmuthia Steud. (1 sp.)

Isolepis R.Br. (69 spp.)

Ficinia Schrad. (87 spp.)

Desmoschoenus Hook.f.

Cyperinae Pax

Cyperus L. (964 spp.)

C3 Cyperus Grade = subgenus Anosporum (Nees) C.B.Clarke

Androtrichum (Brongn.) Brongn.

Courtoisina Soják

Kyllingiella R.W.Haines & Lye

Oxycaryum Nees

C4 Cyperus Clade = subgenus Cyperus

Alinula J.Raynal

Ascolepis Nees ex Steud.

Ascopholis C.E.C.Fisch.

Kyllinga Rottb.

Lipocarpha R.Br.

Mariscus Vahl

Pycreus P.Beauv.

Queenslandiella Domin

Remirea Aubl.

Sphaerocyperus Lye

Torulinium Desv.

Volkiella Merxm. & Czech

Incertae Cedis

Rhynchocladium T.Koyama (1 sp.)