Amblygonocarpus Harms, Nat. Pflanzenfam. Nachtr. II-IV 1: 191. 1897.

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

Amblygonocarpus Harms, Nat. Pflanzenfam. Nachtr. II-IV 1: 191. 1897.

Figs 104 , 106 , 109

Type.

Amblygonocarpus schweinfurthii Harms [= Amblygonocarpus andongensis (Welw. ex Oliv.) Exell & Torre (= Tetrapleura andongensis Welw. ex Oliv.)]

Description.

Unarmed trees 8-20 m tall, 25-75 cm diameter, with a broad, umbrella-shaped crown (Fig. 104I ), buttresses absent, bark grey, scaly (Fig. 104E ); plant glabrous throughout; brachyblasts absent. Stipules minute, linear, caducous. Leaves bipinnate, 20-30 cm long, foliar nectaries absent; pinnae opposite or alternate, 2-6 pairs per leaf; leaflets alternate, 8-16 per pinna, petiolulate, elliptic to obovate-elliptic. Inflorescences axillary, solitary or paired racemes, borne on old wood and subtending the current flush of leaves and thus immersed in the foliage, 5-13 cm long, flowers ca. 50-75 per raceme. Flowers seemingly all bisexual, pseudopedicellate, these abscising with the flowers, ebracteolate; calyx broad, shallow, 5 (6) lobed, valvate in bud; petals lanceolate, 5 (6), free, cream to white, aging yellow, valvate in bud; stamens 10 (12), free, filaments white, anthers dorsifixed, oblong-ovate, eglandular; pollen in calymmate 16 or 32-grained polyads; ovary oblong, sessile, glabrous. Fruits pendent, stipitate, straight, oblong, woody, indehiscent, 10-15 cm long, bluntly tetragonal or subterete in cross section (Fig. 106B ), each side of the fruit ca. 2 cm wide, dark brown, glossy, internally septate between the seeds with spongy, fibrous endocarp, ca. 6-8-seeded. Seeds inserted transversely in the pod, brown, smooth, unwinged, testa hard, pleurogram present.

Chromosome number.

2 n = 28 ( Goldblatt and Davidse 1977).

Included species and geographic distribution.

One species ( A. andongensis ), widespread in savannas from northern Ghana east to Sudan, in the south from Angola through Zambia and Botswana to Tanzania and Mozambique (Fig. 109).

Ecology.

Savannas and deciduous woodlands, frequently on sandy soils, often associated with Senegalia Raf., Burkea Benth. and Albizia Durazz.

Etymology.

From the Greek, ambly - (= blunt), gonia - (= angle), - carpus (= fruit), in reference to the angled fruits.

Human uses.

The seeds of Amblygonocarpus are harvested in the wild and eaten roasted. The roots, bark, and leaves are used in folk medicine to treat a wide variety of ailments. The wood is extremely hard and is used to make furniture, small implements, and heavy-duty flooring; also used as a fuel and to make charcoal ( Fern 2023).

Notes.

Amblygonocarpus is closely related to Tetrapleura and Adenanthera in the recent phylogeny of Ringelberg et al. (2022). The flowers and foliage of Tetrapleura and Amblygonocarpus are quite similar and are sometimes confused when not in fruit. Amblygonocarpus is glabrous throughout with reddish brown petiole, rachis, and pinnae whereas Tetrapleura has pubescence on the petiole, rachis, pinnae, and often leaflets. Flowers are completely glabrous in Amblygonocarpus and the anthers are eglandular; the calyx is always pubescent in Tetrapleura and the anther is equipped with an apical gland. Both genera have tetragonal fruits, but the margins form well-developed wings in Tetrapleura whereas they are bluntly angled in Amblygonocarpus . Adenanthera is rarely confused with the other two genera because of its dehiscent fruits with red seeds and Asian distribution.

Taxonomic references.

Brenan (1959), with illustration.

Figures

Figure 104. Habit and growth form in the Adenanthera clade A Xylia xylocarpa var. kerrii (Craib & Hutch.) I. C. Nielsen scaly bark B Xylia torreana Brenan canopy C Pentaclethra macroloba (Willd.) Kuntze trunk showing buttresses D Tetrapleura tetraptera (Schumach. & Thonn.) Taub. canopy (Harris 9659) E Amblygonocarpus andongensis (Welw. ex Oliv.) Exell & Torre pale grey, scaly bark (Catarino 2067) F Pseudoprosopis gilletii (De Wild.) Villiers liana with leaves and lignified tendrils (Texier 1558) G Adenanthera pavonina L. thin scaly bark H habit I Amblygonocarpus andongensis (Welw. ex Oliv.) Exell & Torre growing in savanna (Coates Palgrave M 806). Photo credits A Dechaphaetkrathok B F du Randt C D DeMelo D DJ Harris E L Catarino F N Texier G, H Shelbyfarmer I M Coates Palgrave.

Figure 106. Fruits and seeds in the Adenanthera clade A Adenanthera pavonina L. dehisced fruits with exposed persistent red seeds B Amblygonocarpus andongensis (Welw. ex Oliv.) Exell & Torre Indehiscent four-angled fruits (Catarino 2067) C Pseudoprosopis fischeri Harms young fruit (Bingham 8055) D Xylia xylocarpa var. kerrii (Craib & Hutch.) I. C. Nielsen young dolabriform pod E Tetrapleura tetraptera (Schumach. & Thonn.) Taub. immature winged, indehiscent pod (Harris 9659) F Pentaclethra macrophylla Benth. pod and recalcitrant seeds G, H Calpocalyx ngouniensis Pellegr. woody valves from dehisced pod (Texier 695). Photo credits A Shelbyfarmer B L Catarino C MG Bingham D B Peroth E DJ Harris 9659 F CJ Porto, Fundacion Tierra Iberica G H N Texier.