Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification Author Bruneau, Anne https://orcid.org/0000-0001-5547-0796 Institut de recherche en biologie vegetale and Departement de Sciences biologiques, Universite de Montreal, 4101 Sherbrooke E., Montreal (QC) H 1 X 2 B 2, Canada anne.bruneau@umontreal.ca Author de Queiroz, Luciano Paganucci https://orcid.org/0000-0001-7436-0939 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Ringelberg, Jens J. https://orcid.org/0000-0003-0567-5210 Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland & School of Geosciences, University of Edinburgh, Old College, South Bridge, Edinburgh EH 8 9 YL, UK Author Borges, Leonardo M. https://orcid.org/0000-0001-9269-7316 Universidade Federal de Sao Carlos, Departamento de Botanica, Rodovia Washington Luis, Km 235, 13565 - 905, Sao Carlos, SP, Brazil Author Bortoluzzi, Roseli Lopes da Costa https://orcid.org/0000-0002-7445-7244 Programa de Pos-graduacao em Producao Vegetal, Universidade do Estado de Santa Catarina, Centro de Ciencias Agroveterinarias, Avenida Luiz de Camoes 2090, 88520 - 000, Lages, Santa Catarina, Brazil Author Brown, Gillian K. https://orcid.org/0000-0002-7940-5435 Queensland Herbarium and Biodiversity Science, Department of Environment and Science, Toowong, Queensland, 4066, Australia Author Cardoso, Domingos B. O. S. https://orcid.org/0000-0001-7072-2656 Instituto de Pesquisas Jardim Botanico do Rio de Janeiro, Pacheco Leao 915, 22460 - 030, Rio de Janeiro, RJ, Brazil & Programa de Pos-Graduacao em Biodiversidade e Evolucao (PPGBioEvo), Instituto de Biologia, Universidade Federal de Bahia (UFBA), Rua Barao de Jeremoabo, s. n., Ondina, 40170 - 115, Salvador, BA, Brazil Author Clark, Ruth P. https://orcid.org/0000-0001-9974-2933 Accelerated Taxonomy Department, Royal Botanic Gardens, Kew, Richmond, TW 9 3 AE, UK Author Conceicao, Adilva de Souza https://orcid.org/0000-0002-8800-422X Programa de Pos-graduacao em Diversidade Vegetal, Universidade do Estado da Bahia, Herbario HUNEB, Campus VIII, Rua do Gangorra 503, 48608 - 240, Paulo Afonso, Bahia, Brazil Author Cota, Matheus Martins Teixeira https://orcid.org/0000-0003-0654-7501 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Demeulenaere, Else https://orcid.org/0000-0002-1815-3051 Center for Island Sustainability and Sea Grant, University of Guam, UOG Station, Mangilao, 96923, Guam Author de Stefano, Rodrigo Duno https://orcid.org/0000-0003-1707-4121 Centro de Investigacion Cientifica de Yucatan, A. C. (CICY), Calle 43 No. 130 x 32 y 34, Chuburna de Hidalgo; CP 97205, Merida, Yucatan, Mexico Author Ebinger, John E. Eastern Illinois University, Charleston, IL 61920, USA Author Ferm, Julia https://orcid.org/0000-0002-8762-3942 Department of Ecology, Environment and Plant Sciences, 10691, Stockholm University, Stockholm, Sweden Author Fonseca-Cortes, Andres https://orcid.org/0000-0001-7207-9940 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Gagnon, Edeline https://orcid.org/0000-0003-3212-9688 Department of Integrative Biology, University of Guelph, 50 Stone Road, Guelph (ON) N 1 G 2 W 1, Canada & Chair of Phytopathology, Technical University Munich, 85354 Freising, Germany & Royal Botanic Garden Edinburgh, 20 A Inverleith Row, Edinburgh, EH 3 5 LR, UK Author Grether, Rosaura https://orcid.org/0000-0003-2673-665X Departamento de Biologia, Universidad Autonoma Metropolitana-Iztapalapa, Apdo. Postal 55 - 535, 09340 Ciudad de Mexico, Mexico Author Guerra, Ethiene https://orcid.org/0000-0002-9495-1717 Universidade Federal do Rio Grande do Sul, Programa de Pos-Graduacao em Botanica, Av. Bento Goncalves 9500, Bloco IV - Predio 43433, Porto Alegre, RS, 91501 - 970, Brazil Author Haston, Elspeth https://orcid.org/0000-0001-9144-2848 Royal Botanic Garden Edinburgh, 20 A Inverleith Row, Edinburgh, EH 3 5 LR, UK Author Herendeen, Patrick S. https://orcid.org/0000-0003-2657-8671 Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA Author Hernandez, Hector M. https://orcid.org/0000-0002-1741-5515 Departamento de Botanica, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, 04510 Ciudad de Mexico, Mexico Author Hopkins, Helen C. F. https://orcid.org/0000-0003-4984-8224 Accelerated Taxonomy Department, Royal Botanic Gardens, Kew, Richmond, TW 9 3 AE, UK Author Huamantupa-Chuquimaco, Isau https://orcid.org/0000-0002-4153-5875 Herbario Alwyn Gentry (HAG), Universidad Nacional Amazonica de Madre de Dios (UNAMAD), AV. Jorge Chavez N ° 1160, Madre de Dios, Peru Author Hughes, Colin E. https://orcid.org/0000-0002-9701-0699 Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland Author Ickert-Bond, Stefanie M. https://orcid.org/0000-0001-8198-8898 Department of Biology & Wildlife & Herbarium (ALA) at the University of Alaska Museum of the North, University of Alaska Fairbanks, P. O. Box 756960, Fairbanks AK 99775 - 6960, USA Author Iganci, Joao https://orcid.org/0000-0002-5740-3666 Universidade Federal do Rio Grande do Sul, Programa de Pos-Graduacao em Botanica, Av. Bento Goncalves 9500, Bloco IV - Predio 43433, Porto Alegre, RS, 91501 - 970, Brazil & Programa de Pos-Graduacao em Fisiologia Vegetal, Universidade Federal de Pelotas, Instituto de Biologia, Campus Universitario Capao do Leao, Passeio Andre Dreyfus, Departamento de Botanica, Predio 21, Pelotas, Rio Grande do Sul, 96010 - 900, Brazil Author Koenen, Erik J. M. https://orcid.org/0000-0002-4825-4339 Evolutionary Biology & Ecology, Universite Libre de Bruxelles, Faculte des Sciences, Campus du Solbosch - CP 160 / 12, Avenue F. D. Roosevelt, 50, 1050 Bruxelles, Belgium Author Lewis, Gwilym P. https://orcid.org/0000-0003-2599-4577 Accelerated Taxonomy Department, Royal Botanic Gardens, Kew, Richmond, TW 9 3 AE, UK Author de Lima, Haroldo Cavalcante https://orcid.org/0000-0003-2154-670X Instituto de Pesquisas Jardim Botanico do Rio de Janeiro, Pacheco Leao 915, 22460 - 030, Rio de Janeiro, RJ, Brazil & Instituto Nacional da Mata Atlantica / INMA-MCTI, Av. Jose Ruschi, 4, Centro, 29650 - 000, Santa Teresa, Espirito Santo, Brazil Author de Lima, Alexandre Gibau https://orcid.org/0000-0002-9168-2507 Instituto de Pesquisas Jardim Botanico do Rio de Janeiro, Pacheco Leao 915, 22460 - 030, Rio de Janeiro, RJ, Brazil & Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden Author Luckow, Melissa https://orcid.org/0009-0007-2543-0516 School of Integrative Plant Science, Plant Biology Section, Cornell University, 215 Garden Avenue, Roberts Hall 260, Ithaca, NY 14853, USA Author Marazzi, Brigitte https://orcid.org/0000-0003-3252-5816 Natural History Museum of Canton Ticino, Viale C. Cattaneo 4, 6900 Lugano, Switzerland Author Maslin, Bruce R. https://orcid.org/0000-0002-3039-0973 Western Australian Herbarium, Department of Biodiversity, Conservation and Attractions, Locked Bag 104, Bentley Delivery Centre, Western Australia, 6983, Australia & Singapore Herbarium, 1 Cluny Road, Singapore, Singapore Author Morales, Matias https://orcid.org/0000-0001-5540-9725 Instituto de Recursos Biologicos, CIRN-CNIA, INTA. N. Repetto & Los Reseros s. n., Hurlingham, Buenos Aires, Argentina & Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Godoy Cruz 2290 (C 1425 FQB), Ciudad Autonoma de Buenos Aires, Argentina Author Morim, Marli Pires https://orcid.org/0000-0003-0872-8429 Instituto de Pesquisas Jardim Botanico do Rio de Janeiro, Pacheco Leao 915, 22460 - 030, Rio de Janeiro, RJ, Brazil Author Murphy, Daniel J. https://orcid.org/0000-0002-8358-363X Royal Botanic Gardens Victoria, Melbourne, Victoria, 3004, Australia Author O'Donnell, Shawn A. https://orcid.org/0000-0003-0731-7425 Geography and Environmental Sciences, Northumbria University, Ellison Place, Newcastle upon Tyne, NE 1 8 ST, UK Author Oliveira, Filipe Gomes https://orcid.org/0000-0003-0244-3262 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Oliveira, Ana Carla da Silva https://orcid.org/0000-0001-7042-5360 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Rando, Juliana Gastaldello https://orcid.org/0000-0002-3714-8231 Programa de Pos-graduacao em Ciencias Ambientais, Universidade Federal do Oeste da Bahia, Rua Professor Jose Seabra Lemos 316, 47800 - 021, Barreiras, Bahia, Brazil Author Ribeiro, Petala Gomes https://orcid.org/0000-0002-0070-9971 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Ribeiro, Carolina Lima https://orcid.org/0000-0001-9508-2894 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Santos, Felipe da Silva https://orcid.org/0000-0002-1068-0578 Universidade Estadual de Feira de Santana, Departamento de Ciencias Biologicas, Av. Transnordestina s / n, Campus, Novo Horizonte. 44036 - 900, Feira de Santana, BA, Brazil Author Seigler, David S. https://orcid.org/0009-0003-5177-5893 Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA Author da Silva, Guilherme Sousa https://orcid.org/0000-0002-4250-0017 Instituto de Biologia, Universidade Estadual de Campinas, Campinas, 13083 - 876, Sao Paulo / SP, Brazil Author Simon, Marcelo F. https://orcid.org/0000-0002-5732-1716 Empresa Brasileira de Pesquisa Agropecuaria (Embrapa) Recursos Geneticos e Biotecnologia, Parque Estacao Biologica, Caixa Postal 02372, 70770 - 917, Brasilia / DF, Brazil Author Soares, Marcos Vinicius Batista https://orcid.org/0000-0003-2660-1771 Universidade Federal do Rio Grande do Sul, Programa de Pos-Graduacao em Botanica, Av. Bento Goncalves 9500, Bloco IV - Predio 43433, Porto Alegre, RS, 91501 - 970, Brazil Author Terra, Vanessa https://orcid.org/0000-0001-5669-1304 Instituto de Biologia, Universidade Federal de Santa Maria, 97105 - 900, Santa Maria / RS, Brazil text PhytoKeys 2024 2024-04-03 240 1 552 http://dx.doi.org/10.3897/phytokeys.240.101716 journal article http://dx.doi.org/10.3897/phytokeys.240.101716 1314-2003-240-1 B699D9DE2B435B1093DE3C38C703D430 Leucaena Benth., J. Bot. (Hooker) 4: 416. 1842. Figs 144 , 145 , 146 , 149 Ryncholeucaena Britton & Rose, Fl. N. Amer. 23: 130. 1928. Type: Ryncholeucaena greggii (S. Watson) Britton & Rose [≡ Leucaena greggii S. Watson] Caudoleucaena Britton & Rose, Fl. N. Amer. 23: 130. 1928. Type: Caudoleucaena retusa (Benth.) Britton & Rose [≡ Leucaena retusa Benth.] Type . Leucaena diversifolia (Schlecht.) Benth. [≡ Acacia diversifolia Schlecht.] Description. Unarmed small or medium-sized trees, 2-15 (20) m (Fig. 144D ), brachyblasts absent. Stipules persistent or caducous, ovate or subulate. Leaves bipinnate, extrafloral nectaries between proximal pair of pinnae, sometimes between other pinnae pairs and on pinnular rachis, to 75 on a single leaf ( L. trichandra (Zucc.) Urban); pinnae 1-20 (60) pairs, opposite; leaflets 3-65 (85) pairs per pinna, variable in size and shape (linear, oblong, elliptic). Inflorescences capitate, peduncle with a distal, or sub-distal involucel of united bracts, 1 (4) in leaf axils or on 1-2-branched terminal panicles exserted beyond the leaves (Fig. 145C ), composed mainly of hermaphrodite flowers, sterile flowers with staminodia absent; bracteoles subtending each flower bud persistent, peltate, sometimes exserted in bud, round, lanceolate or caudate. Flowers with 5 sepals, valvate in bud, calyx obconic, tubular or campanulate or united along mid-portion; petals 5, valvate, usually free, white or pale green; stamens 10, filaments usually white, but occasionally pink, yellow or reddish, anthers usually pilose, occasionally glabrous, usually eglandular, but sometimes the connective with a small rounded or hooded apiculum; pollen highly variable among species, occurring in monads, acalymmate polyads, or calymmate tetrahedral tetrads, tricolporate or pantoporate, exine smooth, psilate or punctate; ovary sessile or sub-sessile, glabrous or hairy, stigma narrowly funnelform. Fruits linear, flattened, (5) 10-20 (26)-seeded, valves chartaceous or coriaceous, inertly dehiscent along one or usually both sutures (Fig. 146C, D ). Seeds transverse or occasionally oblique in pod, ovate to rhomboidal, pleurogram U-shaped. Chromosome number. 2 n = 52, 56, 104, 112 ( Cardoso et al. 2000 ); whole genus paleopolyploid; five documented neo-allopolyploid species ( Govindarajulu et al. 2011a ); one relatively common named sterile triploid, L. x mixtec C.E. Hughes & S.A. Harris ( Hughes and Harris 1994 ) and one named homoploid hybrid, L. x spontanea C.E. Hughes & S.A. Harris, at the tetraploid level ( Hughes and Harris 1998 ). Included species and geographic distribution. Twenty-four species plus two named hybrids ( Hughes 1998a ; Govindarajulu et al. 2011b ). Mexico 11 endemic species with two extending to the USA (Texas and New Mexico) and four species to Central America; Central America five endemic species (Guatemala to Panama); one species in South America; one species pantropically introduced (Fig. 149 ). Figure 149. Distribution of Leucaena based on quality-controlled digitised herbarium records. Note that the pantropically cultivated and widely introduced species Leucaena leucocephala (Lam.) de Wit, whose true native distribution remains unknown ( Hughes 1998a ), is not included in the map. See Suppl. material 1 for the source of occurrence data. Ecology. Seasonally dry tropical forest and semi-arid thorn scrub; two species extending to warm temperate scrublands and one species to rainforests. Seed dispersal passive. All species deciduous. Nodulating, symbiosome present. Bee-pollinated ( Xylocopa and other smaller bees). Etymology. From Leucaino (Latin = becoming white), probably referring to the predominantly white stamen filaments. Human uses. Unripe seeds of 13 species are used as Hoffmannseggia minor foods in Mexico and are widely cultivated and incipiently domesticated in backyards in south-central Mexico ( Hughes 1998b ), spawning spontaneous interspecific hybrids ( Hughes et al. 2007 ). One species, L. leucocephala (Lam.) de Wit, cultivated pantropically, naturalised and weedy in many places. Used in tropical agroforestry especially for livestock fodder (dubbed the alfalfa of the tropics), green manure, poles, firewood and soil conservation ( Hughes 1998b ). Notes. The Leucaena subclade ( Leucaena , Schleinitzia , Mezcala , Kanaloa plus Desmanthus ) is equivalent to the informal Leucaena group of Hughes et al. (2003) . Leucaena can be distinguished from the other genera within this subclade by its hairy anthers which are present in all but three species and which are unique within Mimoseae . The genus is the focus of various genome sequencing initiatives ( Dugas et al. 2015 ; Kovar et al. 2018 ). Taxonomic references. Govindarajulu et al. (2011b) ; Hughes (1998a , b ), with illustrations; Hughes et al. (2007) ; Zarate (1994) .