Sedges (Cyperaceae)
Cyperaceae family
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Currently, a project to complete a new phylogeny-informed classification of Cyperaceae is underway.

So far, this has resulted in a review of current knowledge of Cyperaceae classification based on Sanger sequencing data and embryo data. This work was carried out by Ghent University MSc student Ilias Semmouri for whom I acted as co-supervisor during the academic year 2014-2015.

Having generated targeted sequencing data with the Angiosperms353 baits developed for Kew's Plant and Fungal Trees of Life programme for c. 300 Cyperaceae species, the aim is to publish a new classification of Cyperaceae at tribal, subtribal and generic level in collaboration with the international Cyperaceae research community. Several papers are underway leading up to the classification paper focussed on groups where molecular data is lacking including the C4 Cyperus Clade and tribes Abildgaardieae and Fuireneae.

See also: https://www.kew.org/science/projects/african-cyperaceae
Relevant publications
Larridon I (in press) A linear classification of Cyperaceae to facilitate herbarium curation. Kew Bulletin.

M
esterházy A, Kim C, Cabezas F, Verloove F, Larridon I (2021) A molecular phylogenetic study of African members of tribe Hypolytreae (Mapanioideae, Cyperaceae). Botanical Journal of the Linnean Society: in press.

Maciel Monteiro M, Demarco D,
Larridon I, Prychid CJ, Prenner G (2021) Spicoid morphology of Mapanioideae (Cyperaceae): an evolutionary perspective. Botanical Journal of Linnean Society: 10.1093/botlinnean/boab050. Available online.

Larridon I, Zuntini A, Léveillé-Bourret É, Barrett RL, Starr JR, Muasya M, Villaverde T, Bauters K, Brewer G, Bruhl JJ, Costa SM, Elliott TL, Epitawalage N, Escudero M, Fairlie I, Goetghebeur P, Hipp AL, Jiménez-Mejías P, Sabino Kikuchi IAB, Luceño M, Márquez-Corro JI, Martín-Bravo S, Maurin O, Pokorny L, Roalson EH, Semmouri I, Simpson DA, Thomas WW, Wilson KL, Xanthos M, Forest F, Baker WJ (2021) A new classification of Cyperaceae (Poales) supported by phylogenomic data. Journal of Systematics and Evolution 59(4): 852-895. Available online.

Muasya M, Larridon I (2021) Delimiting the genera of the Ficinia Clade (Cypereae, Cyperaceae) based on molecular phylogenetic data. PeerJ 9:e10737. Available online.

Starr JR, Jiménez-Mejías P, Zuntini AR, Léveillé-Bourret E, Semmouri I, Muasya AM, Baker WJ, Brewer GE, Epitawalage N, Fairlie I, Forest F, Sabino Kikuchi IAB, Pokorny L,
Larridon I (2021) Targeted sequencing supports morphology and embryo features in resolving the classification of Cyperaceae tribe Fuireneae s.l. Journal of Systematics and Evolution 59(4): 809-832. Available online.

Roalson EH, Jiménez-Mejías P, Hipp AL, Benítez-Benítez C, Bruederle LP, Chung K-S, Escudero M, Ford BA, Ford K, Gebauer S, Gehrke B, Hahn M, Hayat MQ, Hoffmann MH, Jin X-F, Kim S, Larridon I, Léveillé-Bourret É, Lu Y-F, Luceño M, Maguilla E, Márquez-Corro JI, Martín-Bravo S, Naczi RFC, Reznicek AA, Spalink D, Starr JR, Uzma, Villaverde T, Waterway MJ, Wilson KL, Zhang S-R (2021) A framework infrageneric classification of Carex (Cyperaceae) and its organizing principles. Journal of Systematics and Evolution. Available online.

Larridon I, Spalink D, Jiménez-Mejías P, Márquez-Corro JI, Martin-Bravo S, Muasya AM, Escudero M (2021) The evolutionary history of sedges in Madagascar. Journal of Biogeography 48: 917-932. Available online.

Larridon I, Zuntini AR, Barrett RL, Wilson KL, Bruhl JJ, Goetghebeur P, Baker WJ, Brewer GE, Epitawalage N, Fairlie I, Forest F, Kikuchi I, Pokorny L, Semmouri I, Spalink D, Simpson DA, Muasya AM, Roalson EH (2021) Resolving the generic limits in Cyperaceae tribe Abildgaardieae using targeted sequencing. Botanical Journal of the Linnean Society. doi: 10.1093/botlinnean/boaa099. Available online.

Larridon I, Villaverde T, Zuntini AR, Pokorny L, Brewer G, Epitawalage N, Fairlie I, Hahn M, Kim J, Maguilla E, Maurin O, Xanthos M, Hipp A, Forest F, Baker WJ (2020) Tackling rapid radiations with targeted sequencing. Frontiers in Plant Science 10: 1655. doi: 10.3389/fpls.2019.01655 Available online. Invited paper for Special Issue on Phylogenomic Approaches to Deal with Particularly Challenging Plant Lineages.

Semmouri I, Bauters K, Léveillé-Bourret É, Starr JR, Goetghebeur P, Larridon I (2019) The phylogeny and systematics of Cyperaceae, the evolution and importance of embryo morphology. Botanical Review 85(1): 1-39 (published online 25 June 2018). Available online.
Carex (Cariceae)
I am collaborating with the Global Carex Group to unravel the relationships in the hyperdiverse genus Carex, resolve its classification, nomenclature, biogeography and species complexes.
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Relevant publications
Villaverde T, Jiménez-Mejías P, Luceño M, Roalson EH, Hipp AL, and the Global Carex Group: Park J, Larridon I, Martín-Bravo S, Naczi RFC, Reznicek AA, Escudero M, Ford BA, Gebauer S, Hoffmann MH, Simpson DA, Starr JR, Wilson KL (2020) A new classification of Carex subgenera supported by a HybSeq backbone phylogeny. Botanical Journal of the Linnean Society. 194(2): 141-163. Available online.

Martín-Bravo S, Jiménez-Mejías P, Villaverde T, Escudero M, Hahn M, Spalink D, Roalson EH, Hipp AL, and the Global Carex Group: Benítez‐Benítez C, Bruederle LP, Fitzek E, Ford BA, Ford KA, Garner M, Gebauer S, Hoffmann MH, Jin X-F, Larridon I, Léveillé‐Bourret É, Lu Y-F, Luceño M, Maguilla E, Márquez‐Corro JI, Míguez M, Naczi R, Reznicek AA, Starr JR (2019) A tale of worldwide success: behind the scenes of Carex (Cyperaceae) biogeography and diversification. Journal of Systematics and Evolution 57(6): 695-718. Available online.
Costularia s.l. (Schoeneae)
Recently, I focussed on the genus Costularia in the broad sense. This research resulted in the publication of two new genera to science, one endemic to New Caledonia and the other endemic to the Seychelles, and aided in resolving the very confusing relationships in this group of Cyperaceae.
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Relevant publications
Larridon I, Rabarivola L, Xanthos M, Muasya AM (2019) Revision of the Afro-Madagascan genus Costularia (Cyperaceae): infrageneric relationships and species delimitation. PeerJ 7:e6528. Available online.

Larridon I, Verboom GA, Muasya AM (2018) Revised delimitation of the genus Tetraria, nom. cons. prop. (Cyperaceae, tribe Schoeneae, Tricostularia clade). South African Journal of Botany 118: 18-22. Available online.

Larridon I, Semmouri I, Bauters K, Viljoen JA, Prychid CJ, Muasya AM, Bruhl JJ, Wilson KA, Goetghebeur P (2018) Molecular phylogenetics of the genus Costularia (Schoeneae, Cyperaceae) reveals multiple distinct evolutionary lineages. Molecular Phylogenetics and Evolution 126: 196-209. Available online.

Larridon I, Verboom GA, Muasya AM (2017) (2555) Proposal to conserve the name Tetraria (Cyperaceae) with a conserved type. Taxon 66(5): 1226-1227. Available online.

Larridon I, Govaerts R, Goetghebeur P (2017) (2554) Proposal to conserve the name Schoenus hornei (Cyperaceae) with a conserved type. Taxon 66(5): 1225-1226. Available online.

Henriette E, Larridon I, Morel C, Goetghebeur P, Senterre B. (2015) Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of Seychelles, including the re-discovery and resurrection of a rare endemic species. Phytotaxa 231(1): 31-41. Available online.
Scleria (Sclerieae)
Another ongoing line of research is the genus Scleria. I acted as co-supervisor for Dr Kenneth Bauters who completed his doctorate at Ghent University on 24 September 2018. During the academic year 2016-2017, I supervised MSc student Javier Galán Díaz, (MSc in Plant and Fungal Taxonomy, Diversity and Conservation organised by Royal Botanic Gardens, Kew and Queen Mary University of London). His MSc project aimed to revise the Scleria species from Madagascar and investigate evolutionary links with mainland African taxa. We have completed a taxonomic revision of the Madagascan species including IUCN Red List assessments. Currently, we are continuing to collaborate on a separate paper concerning the biogeographical history and niche evolution of the genus together with Marcial Escudero. Finally, we aim to complete the Scleria project with a paper looking at species-richness, evolutionary distinctiveness and conservation of Scleria.
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Relevant publications
Larridon I, Galán Díaz J, Bauters K, Escudero M (2020) What drives diversification in a pantropical plant lineage with extraordinary capacity for long-distance dispersal and colonisation? Journal of Biogeography 48(1): 64-77 (published online 2 October 2020). Available online.

Galán Díaz J, Bauters K, Rabarivola L, Xanthos M, Goetghebeur P, Larridon I (2019) A revision of Scleria (Cyperaceae) in Madagascar. Blumea 64: 195-213. Available online.

Bauters K, Larridon I, Goetghebeur P (2019) A taxonomic study of Scleria subgenus Hypoporum: synonymy, typification and a new species-level identification key. Phytotaxa 394(1): 1-49. Available online.

Bauters K, Goetghebeur P, Asselman P, Meganck K, Larridon I (2018) Molecular phylogenetic study of Scleria subgenus Hypoporum (Sclerieae, Cyperoideae, Cyperaceae) reveals several new species to science. PLoS ONE 13(9): e0203478. Available online.

Bauters K, Goetghebeur P, Larridon I (2018) Scleria cheekii, a new species of Scleria subgenus Hypoporum (Cyperaceae, Cyperoideae, Sclerieae). Kew Bulletin 73:27 (6 pages). Available online.

Bauters K, Asselman P, Simpson DA, Muasya AM, Goetghebeur P, Larridon I (2016) Phylogenetics, ancestral state reconstruction, and a new infrageneric classification of Scleria (Cyperaceae) based on three DNA regions. Taxon 65(3): 444-466. Available online.

Bauters K, Meganck K, Vollesen K, Goetghebeur P, Larridon I (2015) Scleria pantadenia and Scleria tricristata: Two spectacular new Scleria subgenus Hypoporum species (Cyperaceae, Cyperoideae, Sclerioideae) from Tanzania. Phytotaxa 227(1): 45-54. Available online.
Tribe Abildgaardieae
I first became actively involved in studying land plant diversity and evolution through my MSc thesis on the African genus Nemum. I described several new species to science. We now know that the small genus Nemum with its specialised spikelet morphology is nested in the larger genus Bulbostylis. Several papers have been published to create the necessary nomenclatural and taxonomic changes. Using the Angiosperms353 baits, we have investigated the relationships in the tribe in order to recircumscribe the genera as monophyletic groups.
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Relevant publications
Rasaminirina F, Rakotoarimanana V, Ralimanana H, Rabehevitra D, Larridon I (accepted pending minor revisions) Bulbostylis itremoensis (Abildgaardieae, Cyperaceae), a new sedge species from Madagascar. Kew Bulletin.

Larridon I, Zuntini AR, Barrett RL, Wilson KL, Bruhl JJ, Goetghebeur P, Baker WJ, Brewer GE, Epitawalage N, Fairlie I, Forest F, Kikuchi I, Pokorny L, Semmouri I, Spalink D, Simpson DA, Muasya AM, Roalson EH (2021) Resolving the generic limits in Cyperaceae tribe Abildgaardieae using targeted sequencing. Botanical Journal of the Linnean Society 196: 163-187. Available online.

Larridon I (2020) Nemum. In: García M.A., Timberlake J.R. (eds.). Flora Zambesiaca, Vol. 14. Cyperaceae, p. 126-130. Royal Botanic Gardens, Kew.

Muasya AM, Goetghebeur P, Larridon I (2020) Zulustylis (Abildgaardieae, Cyperaceae) – a new genus from sub-Saharan Africa. South African Journal of Botany 128: 326-332. Available online.

Larridon I, Goetghebeur P, Roalson EH (2019) New combinations and a new name for including Nemum species in Bulbostylis (Abildgaardieae: Cyperaceae). Phytotaxa 418(1): 112-114. Available online.

Roalson EH, Barrett RL, Wilson KL, Bruhl JJ, Larridon I (2019) Crosslandia setifolia is a partly monoecious Fimbristylis (Abildgaardieae: Cyperaceae). Phytotaxa 399(2): 163-166. Available online.

Roalson EH, Prata AP, Mesterházy A, Chase M, Simpson DA, Thomas WW, Larridon I (2019) A broader circumscription of Bulbostylis (Abildgaardieae: Cyperaceae). Phytotaxa 395(3): 199-208. Available online.

Roalson EH, Simpson DA, Larridon I (2018) (2618) Proposal to conserve Bulbostylis, nom. cons. (Cyperaceae) against an additional name, Nemum. Taxon 67 (3): 642. Available online.

Larridon I, Reynders M, Goetghebeur P. (2008) Novelties in Nemum (Cyperaceae). Belgian Journal of Botany 141 (2): 157-177. Available online.

Larridon I (2006) Systematische revisie en fylogenie van het Afrikaanse genus Nemum (Cyperaceae). MSc thesis, Ghent University, Belgium: 185 p. Available online.
Tribe Cypereae
The Cyperus clade was previously circumscribed as including at least 13 genera. Before I started my PhD, molecular studies at family-level had shown that at least some of the other genera were nested within a large genus Cyperus. However, the exact relationships between the genera remained a mystery. Also, the relationships within the genus Cyperus and within the larger segregate genera were unknown. Additionally, most Cyperus species and segregate genera use C4 photosynthesis. We wanted to answer the following questions: (1) Did the C4 photosynthetic pathway arise only once or multiple times in the Cyperus clade? And (2) Which extant C3 taxa are closest to the switch in character states? To answer these questions, we needed to carry out a more in depth molecular study and additional carbon isotope analyses.

Our results showed a first branching grade of C3 lineages in green in which three segregate genera are nested, and a single clade (in red) encompassing all C4 species including 9 segregate genera. This indicates that the C4 photosynthetic pathway originated only once in the Cyperus clade. The C3 Cyperus section Leucocephali appears to be most closely related to the C4 Cyperus clade and shares their preference for seasonally dry open grasslands, which is unusual for C3 Cyperus species which generally prefer forests and wetlands. This might indicate a transitional stage towards C4 physiology. Eighteen papers were published resulting from research during my PhD and in collaboration with researchers and students at Ghent University, the Royal Botanic Gardens, Kew, University of Cape Town and others. Although initially a PhD student, I quickly took on a leading role in this project as shown by the fact that I was first or corresponding author for most papers and that I supervised a range of undergraduate and graduate students.

The largest Cyperaceae genus in Africa and Madagascar is Cyperus with c. 540 species. Species delimitation in Cyperus is often problematic. Currently, I am supervising Martin Xanthos, Curator-Botanist of the Kew Africa team, who aims to resolve the taxonomy of a species complex characterised by white-glumed spikelets which includes amongst others Cyperus margaritaceus and Cyperus niveus. To achieve this, he is carrying out a morphometric study in combination with targeted sequencing data obtained with the Angiosperms-353 baits developed for Kew's Plant and Fungal Trees of Life programme, to be complemented with a taxonomic revision including IUCN Red List assessments.

Currently, I'm co-supervising a PhD student, Luciana Pereira da Silva, who is investigating the evolution and diversity of Cyperus in Brazil. From January to March 2020, Luciana came on a research stay to the Royal Botanic Gardens, Kew funded by the International Association for Plant Taxonomy and the Society of Systematic Biologists to learn molecular lab techniques and phylogenetic analyses. Sadly, her stay was cut short a few weeks due to the Covid-19 pandemic.

Fitiavana Rasaminirina from the Université d'Antananarivo is undertaking her MSc thesis project on the Cyperaceae from the protected area of Itremo which is managed by he Kew Madagascar Conservation Centre (KMCC). Almost 50% of Cyperaceae species in Madagascar belong to the genus Cyperus.

Linah Rabarivola from KMCC started a project to investigate the endemic species from Cyperus section Incurvi to assess species limits and the conservation status of these morphologically peculiar species. Sadly, Linah passed away in 2019. Her work will be continued at the Royal Botanic Gardens Kew by Kew MSc student Megan Griffiths.

In collaboration with
Muthama Muasya from the University of Cape Town in South Africa, the genera of the Ficinia Clade have recently be reinvestigate for reciprocal monophyly.
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Relevant publications
de Oliveira Ribeiro AR, Pereira-Silva L, Silva Vieira JP, Larridon I, Santos Ribeiro V, Felitto G, Souza Siqueira G, Alves-Araújo A, Alves M (2021) Cyperus prophyllatus: a new endangered aquatic Cyperus species showing unique spikelet disarticulation for the genus described using molecular phylogenetic, anatomical and (micro)morphological data. PLoS ONE 16(6): e0249737. Available online.

Muasya M,
Larridon I (2021) Delimiting the genera of the Ficinia Clade (Cypereae, Cyperaceae) based on molecular phylogenetic data. PeerJ 9:e10737. Available online.

Pereira-Silva L, Trevisan R, Rodrigues AC,
Larridon I (2020) Combining the small South American genus Androtrichum in Cyperus (Cyperaceae). Plant Ecology and Evolution 153(3): 446-454. Available online.

Larridon I, Reynders M (2019) Three new combinations in Cyperus (Cyperaceae). Plant Ecology and Evolution 152(3): 561-562. Available online.

Larridon I, Govaerts R, Bauters K, Goetghebeur P (2016) Cyperus albescens, a new combination in Cyperus (Cyperaceae) for the common (sub)tropical African and Asian species Lipocarpha chinensis. Kew Bulletin 71: 30. Available online.

Larridon I, Bauters K, Huygh W, Reynders M, Goetghebeur P. (2014). Taxonomic changes in C4 Cyperus (Cypereae, Cyperoideae, Cyperaceae): combining the sedge genera Ascolepis, Kyllinga and Pycreus into Cyperus s.l. Phytotaxa 166(1): 33-48. Available online.

Bauters K, Larridon I, Reynders M, Huygh W, Asselman P, Vrijdaghs A, Muasya AM, Goetghebeur P. (2014). A new classification for Lipocarpha and Volkiella as infrageneric taxa of Cyperus s.l. (Cypereae, Cyperoideae, Cyperaceae): insights from species tree reconstruction supplemented with morphological and floral developmental data. Phytotaxa 166(1): 1-32. Available online.

Larridon I, Bauters K, Reynders M, Huygh W, Muasya AM, Simpson DA, Goetghebeur P. (2013). Towards a new classification of the giant paraphyletic genus Cyperus (Cyperaceae): phylogenetic relationships and generic delimitation in C4 Cyperus. Botanical Journal of the Linnean Society 172(1): 106-126. Available online.

Larridon I, Goetghebeur P. (2013). Cyperus steudneri, a new combination in Cyperus (Cyperaceae). Plant Ecology and Evolution 146(1): 138-139. Available online.

Reynders M, Vrijdaghs A, Muasya AM, Larridon I, Goetghebeur P, Smets E. (2012). Gynoecial anatomy and development in Cyperoideae (Cyperaceae, Poales): congenital fusion of carpels facilitates evolutionary modifications in pistil structure. Plant ecology and evolution 145(1): 96-125. Available online.

Larridon I, Reynders M, Huygh W, Bauters K, Vrijdaghs A, Leroux O, Muasya AM, Simpson DA, Goetghebeur P. (2011). Taxonomic changes in C3 Cyperus (Cyperaceae) supported by molecular phylogenetic data, morphology, embryology, ontogeny and anatomy. Plant Ecology and Evolution 144(3): 327-356. Available online.

Larridon I, Reynders M, Huygh W, Bauters K, Van de putte K, Muasya AM, Boeckx P, Simpson DA, Vrijdaghs A, Goetghebeur P. (2011). Affinities in C3 Cyperus lineages (Cyperaceae) revealed using molecular phylogenetic data and carbon isotope analysis. Botanical Journal of the Linnean Society 167: 19-46. Available online.

Reynders M, Huygh W, Larridon I, Muasya AM, Govaerts R, Simpson DA, Goetghebeur P. (2011). Nomenclature and typification of names of genera and subdivisions of genera in the Cypereae (Cyperaceae): 3. Names in segregate genera of Cyperus. Taxon 60(3): 885-895. Available online.

Larridon I, Reynders M, Huygh W, Muasya AM, Govaerts R, Simpson DA, Goetghebeur P. (2011). Nomenclature and typification of names of genera and subdivisions of genera in Cypereae (Cyperaceae): 2. Names of subdivisions of Cyperus. Taxon 60(3): 868-884. Available online.

Vrijdaghs A, Reynders M, Muasya AM, Larridon I, Goetghebeur P, Smets E. (2011). Spikelet and Floral Morphology and Development in Cyperus and Pycreus (Cyperaceae). Plant Ecology and Evolution 144(1): 44-63. Available online.

Huygh W, Larridon I, Reynders M, Muasya AM, Govaerts R, Simpson DA, Goetghebeur P. (2010). Nomenclature and typification of names of genera and subdivisions of genera in Cypereae (Cyperaceae): 1. Names of genera in the Cyperus clade. Taxon 59(6): 1883-1890. Available online.

Vrijdaghs A, Reynders M, Larridon I, Muasya AM, Smets E, Goetghebeur P. (2010). Spikelet structure and development in Cyperoideae, Cyperaceae. Annals of Botany 105(4): 555-571. Available online.

Gautier L, Nusbaumer L, Larridon I, Callmander MW. (2010). Distribution of Cyperus chamaecephalus Cherm., a forest undergrowth species with inconspicuous inflorescences. Candollea 65(2): 364-367. Available online.

Huygh W, Schouppe D, Larridon I, Simpson DA, Goetghebeur P. (2010). Kyllinga cataphyllata (Cyperaceae), a new species from the highlands of West and Central Africa. Blumea 55(3): 291-293. Available online.

Bauters K, Reynders M, Larridon I, Huygh W, Goetghebeur P. (2010). Two New Species of Cyperus (Cyperaceae) from the Zambezian Region of Africa. Novon 20(2): 133-138. Available online.

Larridon I, Reynders M, Goetghebeur P. (2008). Cyperus limiticola, a new name for a Madagascan Cyperus (Cyperaceae). Novon: 18(2): 187-188. Available online.
Main collaborators
United Kingdom
Australia
Belgium
Canada
Madagascar
Linah Rabarivola (Kew Madagascar Conservation Centre)
Fitiavana Rasaminirina (Université d'Antananarivo)
South Africa
Spain
United States of America
Funding