Zygia P. Browne, Civ. Nat. Hist. Jamaica: 279, t. 22, fig. 3. 1756.

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

Zygia P. Browne, Civ. Nat. Hist. Jamaica: 279, t. 22, fig. 3. 1756.

Figs 266 , 268 , 274 , 275

Pithecellobium sect. Caulanthon Benth., London J. Bot. 3: 197. 1844. Type: Pithecellobium unifoliolatum Benth. [≡ Zygia unifoliolata (Benth.) Pittier]

Calliandra sect. Caulanthon (Benth.) Griseb., Fl. Brit. W. I.: 225. 1864. Type: Calliandra latifolia (L.) Griseb. [≡ Zygia latifolia (L.) Fawc. & Rendle]

Marmaroxylon Killip in Record, Trop. Woods 63: 3. 1940. Type: Marmaroxylon racemosum (Ducke) Killip [≡ Pithecellobium racemosum Ducke (≡ Zygia racemosa (Ducke) Barneby & J.W. Grimes)]

Pithecellobium sect. Callozygia Barbosa, Caldasia 14: 400. 1986. Type: Pithecellobium lehmannii Harms [≡ Zygia lehmannii (Harms) Britton & Rose]

Zygia sect. Callozygia (Barbosa) L. Rico, Kew Bull. 46: 495. 1991. Type: Zygia lehmannii (Harms) Britton & Rose [≡ Pithecellobium lehmanii Harms]

Zygia sect. Macrophylla L. Rico, Kew Bull. 46: 495. 1991. Type: Zygia macrophylla (Spruce ex Benth.) L. Rico [≡ Pithecellobium macrophyllum Spruce ex Benth.]

Type.

Zygia latifolia (L.) Fawc. & Rendle [≡ Mimosa latifolia L.]

Description.

Unarmed shrubs or small trees, rarely reaching 20 m height, rarely lianas (Fig. 268E ); bark smooth or flaky, whitish or pale grey. Stipules small, ribbed, caducous, rarely persistent. Leaves bipinnate, rarely paripinnate [ Z. inundata (Ducke) H.C. Lima ex Barneby & J.W. Grimes] or bifoliolate [ Z. unifoliolata (Benth.) Pittier], pinnae 1-10 pairs, opposite; leaflets 1-23 pairs per pinna, sessile, opposite to subopposite, pinnately or palmately veined, frequently with the inner leaflet of proximal pair reduced; petiolar glands sessile, between or immediately below the first pinnae pair, additional glands usually present on the leaf rachis or pinnae rachides between the leaflets insertion, rarely absent ( Z. transamazonica Barneby & J.W. Grimes). Inflorescence units mostly capitate or spicate, exceptionally umbelliform capitula or racemes, isolated or clustered in cauliflorous or ramiflorous synflorescences on the trunk or branches (Fig. 274A, B ), rarely in leaf axils [ Z. odoratissima (Ducke) L. Rico and Z. ocumarensis (Pittier) Barneby & J.W. Grimes]. Flowers usually 5-merous, homomorphic, sessile; calyx gamosepalous, cylindrical to campanulate; corolla gamopetalous, 5-lobed, tubular to funnel shaped; stamens 15-130; intrastaminal disc with a crenately lobed rim (absent in a few pluripinnate species); pollen in 16, 30-celled polyads; ovary sessile or almost so, (7) 8-17-ovulate. Fruits dehiscent through one or both margins, sessile, sometimes attenuate to a pseudo-stipe, flat-compressed or turgid, straight, falcate to slightly falcate, sometimes twisted (Fig. 266J, K ). Seeds flattened, discoid, veined or narrowly winged; testa papery, thin, smooth or wrinkled; pleurogram absent.

Chromosome number.

Unknown.

Included species and geographic distribution.

ca. 60 species from the Neotropics, distributed from Mexico to north-east Argentina, including the Caribbean, with the greatest diversity in Central America, Colombia, the Guianas and north-west Amazon (Fig. 275 ).

Ecology.

Typically plants from wet forest understories, occurring in riparian forests and coastal habitats. They can extend from sea level mangroves up to 750 m elevation, in a few cases reaching 2600 m in northern Andean forests ( Rico 1994; Barneby and Grimes 1997; Ståhl et al. 2010).

Etymology.

From the Greek Zygo referring to the single pair of joined pinnae and stamen filaments that are partially fused (Lewis and Rico Arce 2005).

Human uses.

As nitrogen fixers, Zygia species are used for recovery of degraded areas, and they are used for carpentry in civil constructions and furniture making ( Sprent 2001; Lewis and Rico Arce 2005; Ribeiro et al. 2009).

Notes.

Zygia was described by Browne (1756) based mainly on fruit characters. However, Bentham (1875) included Zygia as a section of his broadly circumscribed Pithecellobium Mart., using characters from leaves and flowers. Zygia was later reinstated as a genus by Fawcett and Rendle (1920) with Z. latifolia as the type species.

The taxonomic limits of Zygia and Marmaroxylon have been controversial, the two having been considered synonyms ( Nielsen 1981a; Barneby and Grimes 1997) or as distinct genera ( Rico-Arce 1991; Lewis and Rico Arce 2005). However, molecular phylogenetic studies ( Ferm et al. 2019) have clearly shown that species with multipinnate leaves ( Marmaroxylon ) are found intermixed with species with unipinnate leaves ( Zygia ) thus supporting the subsuming of Marmaroxylon in Zygia .

Phylogenetic studies also demonstrate the polyphyly of Zygia (including Marmaroxylon ), but the taxonomy still needs to be updated (Ferm et al. in prep.). The non-cauliflorous and multipinnate-leaved Zygia (= Marmaroxylon ) Marmaroxylon ocumarensis is resolved as sister to Macrosamanea ( Ferm et al. 2019; Ringelberg et al. 2022) and could be transferred to this genus ( Ringelberg et al. 2022). Similarly, M. magdalenae Killip ex L. Rico [treated as a synonym of Z. ocumarensis by Barneby and Grimes (1997)] is nested in Jupunba ( Ferm et al. 2019). Finally, Zygia inundata (Ducke) H.C. Lima ex Barneby & J.W. Grimes and Z. sabatieri Barneby & J.W. Grimes are sister to Inga , rather than grouping with the main Zygia clade. Both species have dehiscent fruits, which distinguish them from Inga , which has indehiscent fruits.

Taxonomic references.

Barneby and Grimes (1997); Bentham (1875); Britton and Killip (1936); Britton and Rose (1928), Ferm et al. (2019); Lewis and Rico Arce (2005); Ribeiro et al. (1999); Rico-Arce (1991); Rico (1994); Ståhl et al. (2010).

Figures

Figure 266. Fruit diversity in Inga clade A young pod of Blanchetiodendron blanchetii (Benth.) Barneby & J. W. Grimes B, C Leucochloron incuriale (Vell.) Barneby & J. W. Grimes B dehisced follicular fruits exposing the seeds (C) D lomentiform fruit of Osodendron altissimum (Hook. f.) E. J. M. Koenen E indehiscent and internally septate pod of Osodendron leptophyllum (Harms) E. J. M. Koenen F auriculiform indehiscent pod of Robrichia schomburgkii (Benth.) A. R. M. Luz & E. R. Souza G young fruit of Abarema cochliacarpos (Gomes) Barneby & J. W. Grimes H dehisced twisted pod of Abarema diamantina E. Guerra, Iganci & M. P. Morim exposing the reddish endocarp and bicoloured seeds I dehisced follicle of Macrosamanea amplissima (Ducke) Barneby & J. W. Grimes J Young fruits of Zygia brenesii (Standl.) L. Rico K dehisced pods of Zygia cognata (Schltdl.) Britton & Rose L-O Indehiscent pods of Inga, with fleshy and sweety sarcotesta around the seeds L Inga grazielae (Vinha) T. D. Penn. M Inga capitata Desv. N Inga ingoides (Rich.) Willd. O Inga edulis Mart. Photo credits A, H LP Queiroz B NA Escobar C J Vieira D D Harris E P Latham, www. africanplants. senckenberg. de F LCampbell G, M, N RT Queiroz http: // rubens-plantasdobrasil. blogspot. com / I J Iganci J F Chinchila Romero K S de Jesus Calva L, O D Cardoso.

Figure 268. Habitat and habit diversity in Inga clade A Abarema cochliacarpos (Gomes) Barneby & J. W. Grimes, arborescent shrub in sandy coastal scrub B Robrichia schomburgkii (Benth.) A. R. M. Luz & E. R. Souza, buttressed emergent tree in rainforests C Leucochloron incuriale (Vell.) Barneby & J. W. Grimes, tree with thick corky bark in semi-deciduous forests D Inga bifoliolata D. B. O. S. Cardoso & Amorim, scandent treelet of rainforest understory E Zygia juruana (Harms) L. Rico treelet of the Amazonian inundated forests (igapo) F Osodendron dinklagei (Harms) E. J. M. Koenen, giant tree from the Guinean forests in West tropical Africa. Photo credits A RT Queiroz https: // rubens-plantasdobrasil. blogspot. com / B G Perez Huertas C F Ventura D, E D Cardoso F W Hawthorne.

Figure 274. Leaf and inflorescence diversity in Zygia and Inga (Inga clade) A Zygia juruana (Harms) L. Rico, dense cauliflorous capitate inflorescences B Zygia selloi (Benth.) L. Rico with elongate cauliflorous spikes C part of a leaf of Inga ingoiodes (Rich.) Willd. showing the winged leaf rachis and extrafloral nectaries between leaflet insertions D dense pyramidal spike of Inga grazielae (Vinha) T. D. Penn. E elongate cylindrical spikes of Inga marginata Willd. F pedunculate capitate inflorescence of Inga cordistipula Mart. G terminal panicle of Inga vera Kunth. Photo credits A, D, F D Cardoso B M Magenta C, E, G RT Queiroz https: // rubens-plantasdobrasil. blogspot. com /.

Figure 275. Distribution of Zygia based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.