Inga Mill., Gard. Dict. Abr. 2. 1754.

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/C9E69E67-6E30-6646-789E-C5BAED8016C1
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scientific name	Inga Mill., Gard. Dict. Abr. 2. 1754.
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Treatment

Inga Mill., Gard. Dict. Abr. 2. 1754. View in CoL

Figs 266 View Figure 266 , 268 View Figure 268 , 274 View Figure 274 , 276 View Figure 276

Affonsea A. St.-Hil., Voyage Distr. Diamans Brés, 1: 385. 1833. Type: Affonsea juglandifolia A. St.-Hil. [≡ Inga globularis T.D. Penn.]

Feuilleea Kuntze, Revis. Gen. Pl. 1: 182. 1891. Type: Feuilleea inga (L.) Kuntze [≡ Mimosa inga L. (≡ Inga vera Willd.)]

Type.

Inga vera Willd. [≡ Mimosa inga L.]

Description.

Unarmed trees or treelets to ca. 40 m high, with a smooth cylindrical bole (Fig. 268D View Figure 268 ), bark usually smooth, numerous lenticels arranged in horizontal or vertical rows. Stipules present, up to 8.5 cm diam. Leaves paripinnate (Fig. 274C View Figure 274 ), rarely bifoliolate; petiole and leaf rhachis cylindrical, narrowly margined or winged; foliar glands nearly always present between each pair of leaflets, occasionally present on the leaflet midrib, rarely absent; leaflets 1-11 pairs, often strongly asymmetrical at the base and with eucamptodromus or brochidodromus venation, secondary veins oblique, perpendicular or reticulate. Inflorescences umbellate, capitate, racemose or spicate, usually axillary, rarely ramiflorus or Inga cauliflorus (Fig. 274D-G View Figure 274 ); floral bracts often conspicuous and persistent, occasionally partly fused to form an involucre. Flowers 5-merous and regular; calyx gamosepalous, the tube cup-shaped, funnel-shaped or tubular, nearly always exceeding the lobes, open in bud and then (4) 5 (6)-lobed, or closed in bud and then splitting irregularly, the apex rostrate and then opening by a single lateral slit; corolla gamopetalous, greenish, yellowish-white or bright yellow, rarely pink or red, tubular or rarely funnel-shaped, tube exceeding the lobes; stamens ca. 20-350, united in the lower half into a tube, tube shorter than, equaling or exceeding the corolla, free portion of filaments long-exserted; pollen in 16, 20, 24, 28, 30 or 32-celled polyads; intrastaminal disc small, cup-shaped; gynoecium 1-9-carpellate, ovules 10-32 per ovary. Fruits indehiscent, woody, leathery or fleshy, usually flat or convex, less frequently quadrangular or cylindrical, straight, curved or spirally twisted or coiled (Fig. 266L-O View Figure 266 ), faces usually much broader than the margins, or margins sometimes raised or winged, when cylindrical then margin highly developed and partially or completely covering the faces. Seeds fleshy, thin-walled, the testa developing a thick white sugary sarcotesta (Fig. 266M, N View Figure 266 ); pleurogram absent.

Chromosome number.

2 n = 26, and in some tetraploid species 2 n = 52 ( Pennington 1997).

Included species and geographic distribution.

ca. 300 species, restricted to tropical America. The species are distributed in Mexico, southern Central America, western South America, Venezuela and the Guianas, the coastal states of Brazil and the West Indies. The highest species diversity is concentrated in the Andean foothills of Peru, Ecuador, Colombia and in southern Central America, occupying a wide variety of habitats from sea level to 3000 m ( Pennington 1997) (Fig. 276 View Figure 276 ).

Ecology.

The genus is largely confined to wet forests, having a strong relationship with the germination process of the seeds, as they need shade and high humidity for immediate germination ( Pennington 1997). Some species occur in semi-arid areas, but then are mostly confined to gallery forests along temporary or permanent watercourses.

Etymology.

Derived from “ingá”, the Brazilian name of several species of mimosoid legumes, especially of the genus Inga . Originated from the Tupi word in-gá, which probably means "soaked, stewed", due to the consistency of the pulp that surrounds the seeds ( Ferreira 1986).

Human uses.

The genus has many uses. The fruits are edible, and the fleshy sarcotesta surrounding the seed can be eaten fresh or in recipes (Fig. 266O View Figure 266 ). The earliest records of this usage are from coastal Peru, where remnants of fruits and seeds of Inga feuillei DC. have been recorded from tombs dating back to the Chimu and Mochica periods, ca. 2000 years ago. Ceramics from the same period made in the form of the fruit of I. feuillei have also been found in archaeological remains ( Pennington 1997). Some species have edible embryos, which are used in soups or prepared by boiling in water or by roasting. Species of Inga are widely used by farmers as shade trees, mainly in coffee, cocoa and tea plantations, due to their architecture, which produces a flat or umbrella-shaped evergreen crown ( Pennington 1997). In addition, they are widely used as fuelwood and to produce high volumes of timber in a short period of time ( Pennington 1997). The species are also commonly used in soil restoration and agroforestry ( Pennington 1997).

Notes.

Inga has been supported as monophyletic in several phylogenetic studies of the mimosoid legumes although only about one third of the species have been sampled ( Nicholls et al. 2015; Dexter et al. 2017). Barneby and Grimes (1996) included Inga in the informal Inga alliance together with Macrosamanea , Cojoba Britton & Rose, Zygia , Calliandra Benth., Zapoteca H.M. Hern. and Archidendron F. Muell. Subsequent studies demonstrated that this alliance is polyphyletic and that Inga is probably sister to the genus Zygia ( Koenen et al. 2020a; Ringelberg et al. 2022).

The infrageneric taxonomy has changed importantly over the years. Bentham (1845, 1865, 1875) divided Inga into five sections: Leptinga Benth., Diadema Benth., Bourgonia Benth., Pseudinga Benth. and Euinga . Pennington (1997) remarked that the boundaries of sections and series are blurred, but that the series might be more natural than the sections. Pennington (1997) classified the genus into 14 sections, within which only informal species groups were recognised. The sections are largely based on several overlapping and quantitative characters and are difficult to separate with a simple key, probably reflecting the relatively recent origin and explosive radiation of the genus in Neotropical rainforests ( Pennington and Dick 2009; Dexter et al. 2017).

Taxonomic references.

Bentham (1845, 1875, 1876); Pennington (1997); Poncy (1985); Sousa (1993).