Mimoseae Bronn, Form. Pl. Legumin.: 78, 127, 130. 1822.

Bruneau, Anne, de Queiroz, Luciano Paganucci, Ringelberg, Jens J., Borges, Leonardo M., Bortoluzzi, Roseli Lopes da Costa, Brown, Gillian K., Cardoso, Domingos B. O. S., Clark, Ruth P., Conceicao, Adilva de Souza, Cota, Matheus Martins Teixeira, Demeulenaere, Else, de Stefano, Rodrigo Duno, Ebinger, John E., Ferm, Julia, Fonseca-Cortes, Andres, Gagnon, Edeline, Grether, Rosaura, Guerra, Ethiene, Haston, Elspeth, Herendeen, Patrick S., Hernandez, Hector M., Hopkins, Helen C. F., Huamantupa-Chuquimaco, Isau, Hughes, Colin E., Ickert-Bond, Stefanie M., Iganci, Joao, Koenen, Erik J. M., Lewis, Gwilym P., de Lima, Haroldo Cavalcante, de Lima, Alexandre Gibau, Luckow, Melissa, Marazzi, Brigitte, Maslin, Bruce R., Morales, Matias, Morim, Marli Pires, Murphy, Daniel J., O'Donnell, Shawn A., Oliveira, Filipe Gomes, Oliveira, Ana Carla da Silva, Rando, Juliana Gastaldello, Ribeiro, Petala Gomes, Ribeiro, Carolina Lima, Santos, Felipe da Silva, Seigler, David S., da Silva, Guilherme Sousa, Simon, Marcelo F., Soares, Marcos Vinicius Batista & Terra, Vanessa, 2024, Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification, PhytoKeys 240, pp. 1-552 : 1

Tribe Mimoseae Bronn, Form. Pl. Legumin.: 78, 127, 130. 1822.

Mimosaceae R. Br., in M. Flinders, Voy. Terra Austral. 2: 551. 1814, nom. cons. Type: Mimosa L.

Mimosoideae DC., Prodr. [A.P. de Candolle] 2: 424. 1825. Type: Mimosa L.

Acacieae Dumort., Anal. Fam. Pl.: 40. 1829. Type: Acacia Mill., nom. cons.

Acaciinae Wight & Arn., Prodr. Fl. Ind. Orient.: 267. 1834. Type: Acacia Mill., nom. cons.

Parkiinae Wight & Arn., Prodr. Fl. Ind. Orient.: 279. 1834. Type: Parkia R. Br.

Acaciaceae E. Mey., Comm. Pl. Afr. Austr. 1: 164. 1836. Type: Acacia Mill., nom. cons.

Desmanthinae Benth., J. Bot. (Hooker) 2: 128. 1840. Type: Desmanthus Willd.

Parkieae Endl., Gen. Pl.: 1323. 1840. Type: Parkia R. Br.

Adenantherinae Benth., J. Bot. (Hooker) 4: 331. 1841. Type: Adenanthera L.

Mimosineae J. Presl, Nowočeská Bibl. [ Wšobecný Rostl.] 7: 346: 421. 1846. Type: Mimosa L.

Adenanthereae Benth. & Hook.f., Gen. Pl. 1: 437. 1865. Type: Adenanthera L.

Ingeae Benth. & Hook.f., Gen. Pl. 1: 437. 1865. Type: Inga Mill.

Piptadenieae Benth., Trans. Linn. Soc. London 30: 343, 358. 1875. Type: Piptadenia Benth.

Desmantheae Kuntze, in von Post & Kuntze, Lex. Gen. Phan.: 646. 1903. Type: Desmanthus Willd.

Mimozygantheae Burkart, Darwiniana 3: 447. 1939. Type: Mimozyganthus Burkart

Albizieae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 251. 1943. Type: Albizia Durazz.

Affonseeae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 251. 1943. Type: Affonsea A. St.-Hil. [= Inga Mill.]

Type.

Mimosa L.

Description.

Trees, shrubs, lianas, suffruticose or herbs, occasionally aquatic; unarmed or armed with prickles, spines or thorns. Stipules lateral and free or absent. Leaves bipinnate, less frequently paripinnate or modified into phyllodes (many Acacia , some Mimosa ), rarely absent; pinnae and leaflets mostly opposite, rarely alternate; paraphyllidia (reduced basal leaflet pair on the pinnae) present or absent; specialised extrafloral nectaries often present on the petiole and/or on the primary and secondary rachides. Inflorescence globose, ellipsoid, umbelliform or corymbiform capitula, spikes or spiciform racemes; arising singly, paired or many from axillary fascicles, more frequently clustered in diversely arranged synflorescences. Flowers bisexual or frequently bisexual flowers combined with unisexual and/or sterile flowers in heteromorphic inflorescences, radially symmetrical; hypanthium mostly lacking; sepals and petals (3) 5 (6-8), mostly fused, sepals valvate in bud, rarely imbricate ( Mimozyganthus , Parkia , Pentaclethra ), petal aestivation valvate, rarely imbricate ( Chidlowia , Sympetalandra ), frequently the base of petals and stamens joined into a tube (stemonozone); stamens diplostemonous, haplostemonous or polystemonous, sometimes modified into showy staminodia, free or the filaments fused, anthers basifixed or dorsifixed, dehiscing via longitudinal slits, often with a stipitate or sessile apical gland; pollen commonly in tetrads, bitetrads or polyads, rarely in monads; gynoecium uni- or rarely polycarpellate, 1-many ovulate. Fruits 1-many-seeded, indehiscent or dehiscent along one or both sutures, often explosively or elastically dehiscent, also often lomentum or craspedium, the endocarp indistinct or separate and fragmented into 1-seeded envelopes. Seeds usually with an open (U-shaped) or closed (O-shaped) pleurogram on both faces, sometimes with a fleshy aril or sarcotesta; sometimes winged, hilum usually apical, lens usually inconspicuous; embryo straight. Root nodules present, indeterminate, and always symbiosome-type, or absent (at least 7 genera).

Included genera

(100). Abarema Pittier (2 species), Acacia Mill. (1082), Acaciella Britton & Rose (15), Adenanthera L. (12), Adenopodia C. Presl (7), Afrocalliandra E.R. Souza & L.P. Queiroz (2), Alantsilodendron Villiers (11), Albizia Durazz. (ca. 90), Amblygonocarpus Harms (1), Anadenanthera Speg. (2-4), Anonychium (Benth.) Schweinf. (1), Archidendron F. Muell. (ca. 120), Archidendropsis I.C. Nielsen (11), Aubrevillea Pellegr. (2), Blanchetiodendron Barneby & J.W. Grimes (1), Boliviadendron E.R. Souza & C.E. Hughes (1), Calliandra Benth. (140), Calliandropsis H.M. Hern. & P. Guinet (1), Calpocalyx Harms (11), Cedrelinga Ducke (1), Chidlowia Hoyle (1), Chloroleucon (Benth.) Britton & Rose (10), Cojoba Britton & Rose (13-19), Cylicodiscus Harms (1), Desmanthus Willd. (23), Dichrostachys (DC.) Wight & Arn. (13-14), Ebenopsis Britton & Rose (3), Entada Adans. (40), Enterolobium Mart. (8), Faidherbia A. Chev. (1), Falcataria (I.C. Nielsen) Barneby & J.W. Grimes (3), Fillaeopsis Harms (1), Gagnebina Neck. ex DC. (7), Gretheria R. Duno & Torke (2), Gwilymia A.G. Lima, Paula-Souza & Scalon (7), Havardia Small (3), Heliodendron Gill.K. Br. & Bayly (3), Hesperalbizia Barneby & J.W. Grimes (1), Hydrochorea Barneby & J.W. Grimes (10), Indopiptadenia Brenan (1), Inga Mill. (ca. 300), Jupunba Britton & Rose (37), Kanaloa Lorence & K.R. Wood (1), Lachesiodendron P.G. Ribeiro, L.P. Queiroz & Luckow (1), Lemurodendron Villiers & Guinet (1), Leucaena Benth. (24), Leucochloron Barneby & J.W. Grimes (4), Lysiloma Benth. (8), Macrosamanea Britton & Rose ex Britton & Killip (12), Mariosousa Seigler & Ebinger (14), Marlimorimia L.P. Queiroz, L.M. Borges, Marc.F. Simon & P.G. Ribeiro (6), Mezcala C.E. Hughes & J.L. Contr. (1), Microlobius C. Presl (1), Mimosa L. (615), Mimozyganthus Burkart (1), Naiadendron A.G. Lima, Paula-Souza & Scalon (1), Neltuma Raf. (30), Neptunia Lour. (22), Newtonia Baill. (11), Osodendron E.J.M. Koenen (3), Painteria Britton & Rose (2), Parapiptadenia Brenan (6), Pararchidendron I.C. Nielsen (1), Parasenegalia Seigler & Ebinger (11), Paraserianthes I.C. Nielsen (1), Parkia R. Br. (ca. 35), Pentaclethra Benth. (3), Piptadenia Benth. (28), Piptadeniastrum Brenan (1), Piptadeniopsis Burkart (1), Pithecellobium Mart. (19), Pityrocarpa (Benth.) Britton & Rose (7), Plathymenia Benth. (1), Prosopidastrum Burkart (ca. 6), Prosopis L. (3), Pseudalbizzia Britton & Rose (17), Pseudoprosopis Harms (7), Pseudosamanea Harms (3), Pseudosenegalia Seigler & Ebinger (2), Punjuba Britton & Rose (5), Ricoa R. Duno & Torke (1), Robrichia (Barneby & J.W. Grimes) A.R.M. Luz & E.R. Souza (3), Samanea (Benth.) Merr. (3), Sanjappa E.R. Souza & M.V. Krishnaraj (1), Schleinitzia Warb. ex J.C. Willis (4), Senegalia Raf. (219), Serianthes Benth. (18), Sphinga Barneby & J.W. Grimes (3), Strombocarpa Engelm. & A. Gray (10), Stryphnodendron Mart. (28), Sympetalandra Stapf (5), Tetrapleura Benth. (2), Thailentadopsis Kosterm. (3), Vachellia Wight & Arn. (164), Viguieranthus Villiers (18), Wallaceodendron Koord. (1), Xerocladia Harv. (1), Xylia Benth. (9), Zapoteca H.M. Hern. (22), Zygia P. Browne (ca. 60).

Distribution.

Pantropical, with a few species extending marginally into warm temperate regions in North America and Asia, and extratropical South America, southern Africa and Australia.

Clade-based definition.

The most inclusive crown clade containing Mimosa sensitiva L. and Pentaclethra macrophylla Benth., but not Pachyelasma tessmannii (Harms) Harms, Dimorphandra conjugata (Splitg.) Sandwith or Delonix decaryi (R. Vig.) Capuron (Fig. 5 ).

Notes.

Tribe Mimoseae as circumscribed here broadly coincides with the limits of the old sense subfamily Mimosoideae as adopted in several classical works (e.g., Bentham 1865; Taubert 1894; Hutchinson 1964; Polhill and Raven 1981; Lewis et al. 2005). The Mimosoideae then comprised a morphologically distinct subfamily defined by a syndrome of morphological traits including bipinnate leaves mostly with specialised extrafloral nectaries, flowers relatively small usually packed in dense inflorescences, corolla with valvate aestivation, the relatively long and showy stamens as the most conspicuous part of the flowers, and seeds usually with a pleurogram. Despite having scattered exceptions to almost all of these traits, it was relatively easy to recognise species as being members of the subfamily (here treated as a tribe).

Phylogenetic studies have since shown that most of the genera included in the Mimosoideae comprise a monophyletic group, but nested in a paraphyletic old-sense subfamily Caesalpinioideae ( LPWG 2013, 2017). The morphological links between the two then accepted subfamilies were exemplified by a series of mimosoid-like genera with bipinnate leaves and small flowers clustered in dense spicate inflorescence, such as Dimorphandra Schott and Erythrophleum Afzel. ex R. Br., then classified in the Dimorphandra group of tribe Caesalpinieae ( Caesalpinioideae ; Polhill and Vidal 1981). This morphological transition was also observed in the genus Dinizia , then placed in tribe Mimoseae of subfamily Mimosoideae , but which has the imbricate ascending petal aestivation typical of the non-mimosoid Caesalpinioideae .

When revising the subfamilial classification for the Leguminosae , the Legume Phylogeny Working Group ( LPWG 2013) acknowledged that one of the central problems was how to deal with the large clade that included several (old-sense) Caesalpinioideae lineages and which had the Mimosoideae nested within it. The proposed solution was to subsume subfamily Mimosoideae into a re-circumscribed subfamily Caesalpinioideae that recognised the mimosoid clade in an integrated clade-based phylogenetic classification system ( LPWG 2017). This option was considered more likely to remain stable through time and is the classification system proposed here, in which, within subfamily Caesalpinioideae , a tribal rank is formally ascribed to the entire mimosoid clade (sensu LPWG 2017). Tribe Mimoseae , as circumscribed here, thus broadly corresponds to the old sense subfamily Mimosoideae with three Hoffmannseggia minor changes in generic attribution. The genus Dinizia , once placed in tribe Mimoseae ( Lewis and Elias 1981), has been resolved outside of the mimosoid clade in all phylogenetic analyses ( Luckow et al. 2000, 2003; Wojciechowski et al. 2004; Bruneau et al. 2008; LPWG 2017), but shown only recently to group with the genus Campsiandra (tribe Campsiandreae , page 187) based on phylogenomic data ( Zhang et al. 2020; Ringelberg et al. 2022). Sympetalandra and Chidlowia , classified in tribe Caesalpinieae by Polhill and Vidal (1981), are now clearly supported as members of Mimoseae , even though their respective positions within the tribe are not well resolved. Since LPWG (2017) was published, 19 genera have been newly described or re-instated and four have been reduced into synonymy based on newly available phylogenetic data. Recent phylogenies suggest that nine genera ( Alantsilodendron , Archidendron , Calliandra 1, Calpocalyx , Dichrostachys , Parasenegalia , Senegalia , Xylia , Zygia ) are non-monophyletic and require taxonomic revision to recognise only monophyletic genera ( Ringelberg et al. 2022). As newly circumscribed, tribe Mimoseae currently includes 100 genera and ca. 3510 species.

In Advances in Legume Systematics Part 1, five tribes were recognised in subfamily Mimosoideae : Parkieae , Mimoseae , Mimozygantheae, Acacieae and Ingeae ( Elias 1981a). The small tribe Parkieae was shown to be non-monophyletic, with both genera Parkia and Penthaclethra , as well as the monospecific tribe Mimozygantheae, found to be nested in different positions within Mimoseae ( Luckow et al. 2003, 2005). Similarly, the two large tribes Acacieae and Ingeae ( Elias 1981a; Lewis 2005c; Lewis and Rico Arce 2005), which grouped the polystemonous mimosoid legumes, have also been shown to be non-monophyletic in several phylogenetic analyses (e.g., Miller et al. 2003; Brown et al. 2008; Bouchenak-Khelladi et al. 2010). Genera of tribe Ingeae were grouped in five informal alliances by Barneby and Grimes (1996), a system that was later elaborated to six alliances by Lewis and Rico Arce (2005), but which have all also been shown to be non-monophyletic except one. The recognition at the generic level of isolated lineages and segregates of Pithecellobium initiated by Nielsen (1981a) and Barneby and Grimes (1996, 1997), and pursued in Advances in Legume Systematics 14, Part 1 ( Hughes et al. 2022a), has resolved many issues of generic non-monophyly. Even though the classification of Mimosoideae has been known to be unsatisfactory for the last two decades, lack of support and conflicting hypotheses of relationships between studies using different molecular markers and taxonomic sampling (e.g., Luckow et al. 2003, 2007; Miller et al. 2003; Brown et al. 2008; Bouchenak-Khelladi et al. 2010; LPWG 2017) meant that no new taxonomic arrangement could be proposed. The phylogenomic analyses of Koenen et al. (2020a), subsequently confirmed by Ringelberg et al. (2022) with broader taxon sampling, have enhanced resolution, prompting recognition of two nested higher-level clades subtended by relatively long internodes. The core mimosoid clade groups the majority of the Mimoseae , including all of the larger genera, and almost all of the armed mimosoids (genera and species with stipular spines, spinescent shoots, and/or prickles) ( Koenen et al. 2020a). The ingoid clade includes all genera of tribes Ingeae and Acacieae (sensu Elias 1981a; Lewis 2005c; Lewis and Rico Arce 2005), except Vachellia , and thus recognises as a clade all genera with polystemonous flowers (except Vachellia ) and a synandrous androecium ( Koenen et al. 2020a), although neither of these characters are universal within the clade. However, relationships amongst the lineages of the ingoid clade remain difficult to resolve even with large phylogenomic datasets, likely the consequence of rapid speciation leading to low phylogenetic signal and a putative hard polytomy comprising six or seven lineages ( Koenen et al. 2020a).

Despite this putative hard polytomy along the backbone of the ingoid clade, the phylogenomic backbone of the Mimoseae of Koenen et al. (2020a) and Ringelberg et al. (2022) (Fig. 5 ) provides a solid framework for recognizing 17 lower-level clades that together include 86 of the 100 genera in tribe Mimoseae . Two of these clades were not recognised by Koenen et al. (2020a) nor Ringelberg et al. (2022), and are added here following disintegration of the genus Prosopis proposed by Hughes et al. (2022b). The phylogenetic positions of five genera were poorly or not resolved in terms of their closest relatives: Chidlowia and Sympetalandra with respect to the Adenanthera clade and the remainder of Mimoseae ; Cylicodiscus relative to the Prosopis clade and the remainder of the core mimosoids; and Cedrelinga and Pseudosamanea with respect to their positions in the ingoid clade. A sixth taxon, Lachesiodendron , is resolved as sister to a big clade that includes the Stryphnodendron , Mimosa and ingoid clades (60 genera) and is considered here as an isolated lineage. In addition, eight genera are placed in sequential order in two grades rather than being resolved in one of the 17 clades. Four genera are part of a grade that subtends the core mimosoid clade and is here informally designated as the Newtonia grade and four genera, constituting the earliest-diverging lineages in the ingoid clade, are part of a grade that is here informally referred to as the Senegalia grade.

The alternative solution for classification of this group, that of recognising multiple tribes within the mimosoid clade, is untenable given the imbalanced, “ladder-like” phylogenomic backbone of the mimosoid legumes (Fig. 5 ) ( Koenen et al. 2020a; Ringelberg et al. 2022), with eight genera forming grades subtending large clades and several genera with unresolved or phylogenetically isolated positions. This alternative solution would result in a system of more than 30 tribes, of which more than one third would be monogeneric and many others would comprise only two to five genera, which would be impractical and cumbersome and lead to an unnecessary proliferation of supra-generic Linnean names. We thus chose to recognise the entire mimosoid clade as one tribe, the Mimoseae , with a circumscription roughly equivalent to the old-sense subfamily Mimosoideae . The following treatments provide formal descriptions and information for the 17 well-supported lower-level clades, each formally defined and named after a characteristic genus of the clade; sequentially ordered single genus lineages in two grades, these informally labelled also by a genus characteristic of the grade; and six monogeneric lineages whose phylogenetic placements are either unresolved or isolated in Mimoseae .

Thus, in the following taxonomic arrangement, 25 treatments are presented for tribe Mimoseae (the numbers between brackets refer to the number of genera):

Tribe Mimoseae

13. Adenanthera clade (7 genera)

14. Sympetalandra (1)

15. Chidlowia (1)

16. Entada clade (3)

17. Newtonia grade (4)

Core mimosoid clade

18. Cylicodiscus (1)

19. Prosopis clade (2)

20. Neltuma clade (3)

21. Dichrostachys clade (14)

22. Parkia clade (3)

23. Lachesiodendron (1)

24. Stryphnodendron clade (7)

25. Mimosa clade (3)

Ingoid clade

26. Senegalia grade (4)

27. Calliandra clade (3)

28. Zapoteca clade (5)

29. Cojoba clade (3)

30. Pithecellobium clade (7)

31. Archidendron clade (9)

32. Cedrelinga (1)

33. Pseudosamanea (1)

34. Jupunba clade (4)

35. Samanea clade (2)

36. Albizia clade (3)

37. Inga clade (8)

Figures

Figure 5. Phylogeny of tribe Mimoseae showing the clade-based classification of the tribe with two named higher-level and 17 named lower-level clades. The names and phylogenetic placements of all 100 Mimoseae genera are shown, and known generic non-monophyly is indicated with terminal names of non-monophyletic genera in bold. The most likely placement of the unsampled genus Microlobius is indicated with a dashed line; see Stryphnodendron clade treatment (page 319) for details. Branch lengths are expressed in coalescent units, and terminal branch lengths have been assigned an arbitrary uniform length for visual clarity. Monophyletic genera are represented by single branches; see Suppl. material 2 for a phylogeny with all accessions. See Suppl. material 3 for gene tree support across the phylogeny. The phylogeny is a pruned version of the backbone phylogeny of Ringelberg et al. (2023) where full details of the data and phylogenomic analysis methods are presented.