Erythrophleum Afzel. ex R. Br., Denham, Clapperton & Oudney, Narr. Travels Africa: 235. 1826.

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

Erythrophleum Afzel. ex R. Br., Denham, Clapperton & Oudney, Narr. Travels Africa: 235. 1826.

Figs 99 , 100 , 101

Erythrophleum Afzel. ex G. Don, Gen. Hist. 2: 424. 1832. Type: Erythrophleum guineense G. Don [= Erythrophleum suaveolens (Guill. & Perr.) Brenan], nom. superfl.

Fillaea Guill. & Perr., Fl. Seneg. Tent. 1: 242, pl. 55. 1832. Type: Fillaea suaveolens Guill. & Perr. [≡ Erythrophleum suaveolens (Guill. & Perr.) Brenan]

Mavia G. Bertol., Mem. Reale Accad. Sci. Ist. Bologna 2: 570. 1850. Type: Mavia judicialis G. Bertol. [= Erythrophleum suaveolens (Guill. & Perr.) Brenan]

Laboucheria F. Muell., J. Proc. Linn. Soc., Bot. 3: 158. 1859. Type: Laboucheria chlorostachya F. Muell. [≡ Erythrophleum chlorostachys (F. Muell.) Baill.]

Type.

Erythrophleum suaveolens (Guill. & Perr.) Brenan

Description.

Unarmed trees to 30 m, treelets, rarely shrubs; trunk with rough bark; short shoots absent. Stipules very small, caducous. Leaves bipinnate; extrafloral nectaries present (7 species) or absent (3), with the secretory surface sunken in a pit capped by a small round pore ( Pascal et al. 2000); pinnae 2-7 pairs, opposite or subopposite, articulated with leaf rachis; leaflets (4) 7-17 per pinna, alternate, mostly elliptical or ovate to oblong with an acuminate to acute, rarely rounded apex, petiolulate, pinnately veined, mostly asymmetrical because of slightly displaced midvein; stipels absent. Inflorescences densely flowered, elongate spicate racemes, usually clustered in ample terminal panicles; bracts small, caducous; bracteoles absent. Flowers small, actinomorphic, bisexual, shortly pedicellate, subsessile, greenish-yellow or white; hypanthium cupular to tubular; sepals 5, joined at the base or to the middle, lobes imbricate, usually open from an early stage; petals 5, free, imbricate, sessile, pubescent, oblanceolate, narrowed towards base; stamens 10, free, more or less equal or alternately longer and shorter, filaments glabrous or pubescent, anthers dehiscing longitudinally; pollen in tricolporate, psilate monads; intrastaminal disk absent; ovary long-stipitate, tomentose or densely pubescent, tapering into a short conical style, stigma minute, punctiform, minutely ciliolate, ovules numerous. Fruits two-valved legumes, flattened, straight or slightly curved, oblong or oblong-elliptic, 2-11-seeded, dehiscing through both margins, not internally septate; valves thin, woody or coriaceous, not becoming twisted, mostly smooth, without prominent venation. Seeds globose to ellipsoid, only slightly compressed, pleurogram absent.

Chromosome number.

2 n = 24, 28 ( Goldblatt 1981b; Okeyo 2006).

Included species and geographic distribution.

Twelve species, five in tropical sub-Saharan Africa and Madagascar, four in eastern and south-eastern Asia (south-eastern China, Cambodia, Laos, Vietnam, Thailand, Taiwan) and three in northern Australia (Fig. 100 ). Introduced in Malaya and Sri Lanka.

Ecology.

Tropical lowland wet forests in western Africa and south-eastern Asia, seasonally dry forests, woodlands and savannas in central-southern Africa and Australia.

Etymology.

From Greek, erythros (= red) and phloio (= bark), in reference to the red juice which flows from the trunk when cut.

Human uses.

Almost all parts of the plants of species of Erythrophleum are highly toxic for humans and livestock, due mostly to alkaloids, which have a Digitalis -like action on the heart, and to saponins ( Margaret 1959; Ha et al. 2017). Many species are used for therapeutic purposes in various local communities in Africa and Asia (reviewed in Son 2019; Barrett and Barrett 2023), especially for cardiovascular diseases [ E. africanum (Welw. ex Benth.) Harms, E. suaveolens ], leishmaniasis ( E. suaveolens ), to invigorate and promote blood circulation ( E. fordii Oliv.), or for anticonvulsant and anti-inflammatory properties ( E. suaveolens ). The powdered bark of E. lasianthum Corbishley is taken as a snuff to relieve headaches, as a remedy for other pains and fever, and to cure lung sickness in cattle.

The crushed bark of some species ( E. lasianthum and E. suaveolens ) is used as a fish and rat poison and crushed seeds are used as a component of arrow poison ( Lewis 2005b). West African species are known as 'ordeal trees’ or 'poison d’épreuve’ because a poisonous concoction made of the bark of some species is used in “Sassywood”, a drink used in a form of trial by ordeal that was in use in West Africa ( Leeson and Coyne 2012).

Timber of some species, usually named as ‘Tali’, is used for railway sleepers, boat building and canoes, heavy construction and joinery, firewood, and charcoal ( Lewis 2005b). Erythrophleum chlorostachys (including E. pubescens R.L. Barrett & M.D. Barrett and E. arenarium R.L. Barrett & M.D. Barrett) is one of the densest native timbers of Australia ( Barrett and Barrett 2023). Several species of Erythrophleum are threatened by over-exploitation for medicinal or timber uses ( Barrett and Barrett 2023).

Notes.

Together the twelve species of Erythrophleum comprise a morphologically cohesive genus, diagnosed by the combination of macrophyllidious bipinnate leaves, pedicellate flowers with straight and almost erect sepals and petals, and a long stipitate ovary tapering to a short conical style. The genus can be differentiated from Pachyelasma by the length of the ovary stipe (long in Erythrophleum vs. short in Pachyelasma ), flower colour (green to greenish-yellow vs. reddish) and fruits (thin woody or leathery valves and margins not thick vs. resinous valves and thick, raised margins).

There is some controversy regarding the date and place of publication and the type species of the genus. Don (1832) provided an elaborate description of the genus and proposed the new species E. guineense G. Don, and this has sometimes been accepted as the original publication. However, the earlier publication by Brown (1826), which included only a very brief description of the genus characters, is nonetheless considered sufficient to make the publication valid, and this is adopted here, following Barrett and Barrett (2023). Erythrophleum Afzel. ex G. Don is thus considered a later homonym and therefore invalidly published.

Seven of the twelve species have been included in various molecular phylogenetic and genetic studies, all of which support the monophyly of the genus as sampled ( Bruneau et al. 2001, 2008; Herendeen et al. 2003a; Duminil et al. 2013; LPWG 2017; Koenen et al. 2020a; Zhang et al. 2020; Ringelberg et al. 2022; Barrett and Barrett 2023).

Extrafloral nectaries were first reported in the 1980's and they are now known to be present on the leaf rachis of at least seven of the twelve species ( Pascal et al. 2000). Although they have a simpler structure than extrafloral nectaries of the Mimoseae , they have a similar histological structure and probably play a similar role in mediating ant-plant defense systems ( Pascal et al. 2000; Marazzi et al. 2019). Pollen grains of Erythrophleum are reported to be the smallest found in Caesalpinioideae , together with those of Burkea ( Banks and Lewis 2009). Small insects such as beetles, bees and wasps are the main visitors of flowers of E. fordii Oliv. and flies were reported on flowers of E. suaveolens ( Zhu et al. 2013). Seeds in fresh pods are surrounded by a mucilage that might have a nutritive value; this is supported by the finding of seeds in the faeces of primates, including gorillas ( Duminil et al. 2016).

Taxonomic references.

Aubréville (1968); Barrett and Barrett (2023); Brenan (1967, with illustration); Larsen et al. (1980); Ross (1977).

Figures

Figure 99. Habit, bark and foliage of Erythrophleeae A Erythrophleum fordii Oliv. at Hung Temple, Vietnam B bark of Erythrophleum couminga Baill. in Madagascar C Pachyelasma tessmannii (Harms) Harms in Congolian rainforest D, E, H Erythrophleum chlorostachys Baill. D rugous bark E tree in northern Australian savannas H foliage F Erythrophleum lasianthum Corbishley foliage G Erythrophleum suaveolens (Guill. & Perr.) Brenan foliage and terminal inflorescences, Ntumbachusi falls, Zambia. Photo credits A Hungda (https: // tropical. theferns. info / image. php? id = Erythrophleum + fordii) B Solofo Eric Rakotoarisoa, iNaturalist (https: // www. inaturalist. org / photos / 42581094) C Bart Wursten (https: // www. flickr. com / photos / zimbart / 8212743587 / in / photolist-dvJsxn-dvJnwi) D, E, H G Mahajan (https: // alchetron. com / Erythrophleum-chlorostachys) F JMK (https: // wikiwand. com / en / Erythrophleum _ lasianthum) G MG Bingham (https: // malawiflora. com / speciesdata / image-display. php? species _ id = 126540 & image _ id = 8).

Figure 100. Distribution of Erythrophleum based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.

Figure 101. Tribe Erythrophleeae inflorescences, fruits and seeds A-D Spicate racemes of species of Erythrophleum with small flowers, erect sepals and petals and hairy stamen filaments A E. suaveolens (Guill. & Perr.) Brenan with a visiting fly B E. chlorostachys (F. Muell.) Baill. (Ironwood) C, D E. lasianthum Corbishley E-I Fruits and seeds E dehisced fruits of Erythrophleum suaveolens F, G ripe fruits of Erythrophleum lasianthum H, I dispersed fruits of Pachyelasma tessmannii (Harms) Harms on the forest floor, showing the flat valves and raised margins. Photo credits: A AlkalIn (https: // commons. wikimedia. org / wiki / File: Flowers _ of _ Erythrophleum _ suaveolens. jpg) B T Harley (https: // territorynativeplants. com. au / erythrophleum-chlorostachys-ironwood) C, D SAplants E Oliver Haumann, iNaturalist (https: // www. inaturalist. org / photos / 60428121) F, G JMK (https: // commons. wikimedia. org / wiki / File: Erythrophleum _ lasianthum, _ loof _ en _ peule, _ Manie _ van _ der _ Schijff _ BT, _ a. jpg) H B Wursten (https: // flickr. com / photos / zimbart / 8212726705) I T Stevart (https: // tropicos. org / ImageDownload. aspx? imageid = 100336252).