Cassieae Bronn, Form. Pl. Legumin.: 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

publication ID	https://dx.doi.org/10.3897/phytokeys.240.101716
persistent identifier	https://treatment.plazi.org/id/6841D32A-CCA2-8179-E525-C7583F93D116
treatment provided by	PhytoKeys by Pensoft
scientific name	Cassieae Bronn, Form. Pl. Legumin.: 130. 1822.
status

Treatment

Tribe Cassieae Bronn, Form. Pl. Legumin.: 130. 1822.

Figs 21 View Figure 21 , 22 View Figure 22 , 23 View Figure 23 , 24 View Figure 24 , 25 View Figure 25 , 26 View Figure 26 , 27 View Figure 27 , 28 View Figure 28 , 29 View Figure 29 , 30 View Figure 30 , 31 View Figure 31 , 32 View Figure 32 , 33 View Figure 33

Cassiaceae Vest, Anleit. Stud. Bot.: 270, 291. 1818. Type: Cassia L.

Cassia Irregulares Bronn, Form. Pl. Legumin.: 13. 1822. Type: Cassia L.

Cassiinae Wight & Arn., Prodr. Fl. Ind. Orient.: 280. 1834. Type: Cassia L.

Cassioideae Burmeist., Handb. Naturgesch.: 319. 1837. Type: Cassia L.

Melanoxyleae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 254. 1943. Type: Melanoxylum Schott

Type.

Cassia L.

Included genera

(7). Batesia Spruce ex Benth. (1 species), Cassia L. (39), Chamaecrista (L.) Moench (361), Melanoxylum Schott (1), Recordoxylon Ducke (3), Senna Mill. (287), Vouacapoua Aubl. (3).

Description.

Trees, shrubs, subshrubs or vines. Stipules diverse in shape and size, persistent or caducous. Leaves bifoliolate, paripinnate and/or imparipinnate, extrafloral nectaries present in Batesia and Vouacapoua , and in several species of Chamaecrista and Senna , on the petiole and/or leaf rachis, and/or peduncles of inflorescences; leaflets opposite, subopposite or alternate. Inflorescences racemes or panicles, terminal, axillary and sometimes ramiflorous. Flowers hypogynous or perigynous, bilaterally symmetrical, radially symmetrical or asymmetrical; sepals 5, free; petals 5, free, equal, subequal or differentiated; stamens 2-10, free, homomorphic or heteromorphic, anthers poricidal ( Cassia , Chamaecrista and Senna ) or longitudinally dehiscent; pollen unknown for most genera, 3-colporate with long apertures in Chamaecrista and Senna ; ovary sessile or stipitate. Fruit a legume, follicle, indehiscent or dehiscent, with valves opening elastically or not. Seeds mostly compressed, exarillate, variable in shape and colour.

Distribution.

The tribe has a pantropical distribution in wet forests, seasonally dry forests and woodlands, savannas and deserts, a few species extending to temperate areas. The highest diversity of the richest genera ( Chamaecrista and Senna ) occurs in the Neotropical region.

Clade-based definition.

The most inclusive crown clade containing Cassia fistula L. and Melanoxylum brauna Schott, but not Ceratonia siliqua L., Dimorphandra conjugata (Splitg.) Sandwith or Mimosa sensitiva L. (Fig. 21 View Figure 21 ).

Notes.

Tribe Cassieae sensu Irwin and Barneby (1981) was divided into five subtribes which included a total of 20 genera: Cassiinae Wight & Arn. (3 genera), Ceratoniinae H.S. Irwin & Barneby (1), Dialiinae H.S. Irwin & Barneby (13), Duparquetiinae H.S. Irwin & Barneby (1) and Labicheinae H.S. Irwin & Barneby (2). However, ever since the first molecular phylogenies, the tribe has never been supported as monophyletic ( Doyle et al. 1997, 2000; Bruneau et al. 2001, 2008; Kajita et al. 2001; LPWG 2017) and all recent analyses support as monophyletic what was then considered subtribe Cassiinae (comprising Cassia , Chamaecrista and Senna ), but only with the inclusion of four other genera previously placed in the Peltophorum group of tribe Caesalpinieae by Polhill and Vidal (1981) (e.g., Haston et al. 2003, 2005; Bruneau et al. 2008; Manzanilla and Bruneau 2012; Ringelberg et al. 2022).

Cassia , Chamaecrista and Senna are the largest genera in the tribe. Because of similarity in floral morphology, they were all treated under the single genus Cassia until they were segregated by Irwin and Barneby (1981) based on floral, mainly in the androecium configuration (Fig. 22 View Figure 22 ), and fruit differences. The recognition of Cassia , Chamaecrista and Senna is now well established and each of the three genera is supported as monophyletic in well-sampled phylogenetic analyses ( Marazzi et al. 2006; Conceição et al. 2009; Rando et al. 2016; LPWG 2017; Souza et al. 2021). Although the three genera were traditionally considered closely related, phylogenetic analyses have shown that they do not form a clade ( Bruneau et al. 2008; LPWG 2017), Chamaecrista often being resolved as more closely related to Batesia , Melanoxylum and Recordoxylon (Fig. 21 View Figure 21 ).

The position of Vouacapoua has proved more difficult to resolve. Even though not sampled by Ringelberg et al. (2022; Fig. 21 View Figure 21 ), it is included here in Cassieae based on other phylogenetic analyses. Haston et al. (2005), who sampled two of the three species of Vouacapoua , found the genus to be not monophyletic, but this unexpected result was due to a sampling error [the sequence used [ Andira aubletii (= Vouacapoua americana ), GenBank accession AY899701.1] is from Connarus conchocarpus F. Muell ( Connaraceae )]. In the LPWG (2017) matK analysis that includes all three species, the genus is supported as monophyletic and in all phylogenetic analyses, Vouacapoua is resolved as part of, or as sister, to the Cassieae clade ( Bruneau et al. 2008; Marazzi and Sanderson 2010; Manzanilla and Bruneau 2012; LPWG 2017; Kates et al. 2024).

Cassieae is a morphologically heterogeneous group, with only a few features shared among all or nearly all genera. All Cassieae have once-pinnate or bifoliolate leaves, most species have yellow petals, with only a few having red, orange, pink or white ones. Cassia , Senna and Chamaecrista are characterised by poricidal anthers (Fig. 22 View Figure 22 ). These three genera exhibit a suite of floral traits associated with the specialised pollination mode called buzz pollination, in which bees vibrate flowers to release pollen through the anther pores or slits ( Gottsberger and Silberbauer-Gottsberger 1988). Recent phylogenies, which do not group these three genera together, suggest this specialised pollination mode likely evolved more than once within Cassieae . Another unusual feature is that some Cassieae species have stomata on both leaflet surfaces, otherwise present in only a few other caesalpinioid legume clades ( Herendeen et al. 2003a; Bruneau et al. 2008). Extrafloral nectaries are reported in Batesia , Chamaecrista , Senna and Vouacapoua but are lacking in Cassia , Melanoxylum and Recordoxylon ( Marazzi et al. 2019; Cota 2020a). Although in Caesalpinioideae the ability to nodulate rarely occurs outside tribe Mimoseae , two Cassieae genera, Chamaecrista and Melanoxylum , are known to nodulate ( Sprent 2001; Faria et al. 2022). Not all species of Chamaecrista are known to nodulate and those that do differ in the type of nodule anatomy ( Faria et al. 2022; Casaes et al. 2023).