Burkea Hook., Icon. Pl. 6: t. 593. 1843.

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

Burkea Hook., Icon. Pl. 6: t. 593. 1843.

Figs 88 , 89 , 93

Type.

Burkea africana Hook.

Description.

Unarmed shrubs or small trees, exceptionally reaching 20-30 (35) m; trunk not buttressed; brachyblasts absent; indumentum on leaves and inflorescences composed by simple ferrugineous trichomes. Stipules minute, caducous. Leaves bipinnate, clustered at the tip of the branches; petiole and rachis together 7-32 cm long; pinnae (1) 2-5 (7) pairs; leaflets 5-15 (18) per pinna, alternate. Inflorescences elongate spiciform racemes 5-30 cm long, crowded at the tip of branches. Flowers small, whitish, sweet-scented, 5-merous, diplostemonous; calyx campanulate; petals obovate or elliptic-obtuse, glabrous; stamens 10, homomorphic; anthers oblong, anther glands present; pollen tricolpate monads; ovary subsessile, hirsute, 1-2-ovulate, style very short, thick, stigma conspicuous, capitate. Fruit samaroid, oblong or elliptical, flat, indehiscent, 1 (2)-seeded. Seed obovate, compressed, albuminous, cotyledon thin, flat, radicle short.

Chromosome number.

2 n = 28 ( Turner and Fearing 1959).

Included species and geographic distribution.

Monospecific ( B. africana ), widespread in Africa (except for the rainforest regions), occurring mainly in the west, centre and south of the continent, extending into Senegal, Sudan and Uganda, south to Namibia, Botswana and northern South Africa (Fig. 93 ).

Ecology.

The species inhabits savannas and seasonally dry forests at elevations from 40-1740 m. Trees with a bole diameter above 12.5 cm are fire resistant, being sufficiently protected by their corky bark. It is frequent and abundant in many regions (e.g., southern Africa), but often occurs in a dispersed and non-aggregated pattern.

Etymology.

Named after the British botanist Joseph Burke (1812-1873), who collected plants and animals (especially in South Africa) for the Earl of Derby.

Human uses.

An edible gum is produced from the stem, tender young leaves are cooked and eaten as a vegetable while young flowers are eaten in sauces. The bark, roots and leaves are commonly used in traditional medicine ( Mathisen et al. 2002). The bark is used to treat fevers, coughs, colds, catarrh, pneumonia, stomach obstruction, menorrhoea, headaches, inflammation of tongue and gums, poisoning and skin diseases. The powdered bark is applied externally to ulcers and wounds, and to treat scabies. Burkea africana yields durable timber used in construction, carpentry and for charcoal ( Neya et al. 2004; Lewis 2005b).

Notes.

Burkea is the most unusual genus within the tribe, with young leaves and inflorescences clustered at the tip of shoots, capitate stigma, and samaroid, monospermic fruits, whereas the other genera have leaves and inflorescence which are not clustered at the tip of shoots, small stigma, and multi-seeded legumes. The dispersal of the flat and dry fruits of Burkea is possibly by wind since the trees occur in dry and open environments ( Wilson and Witkowski 2003).

Taxonomic references.

Arbonnier (2004); Brummitt et al. (2007); Burkill (1995); Dry (1993); Oliver (1871); Palmer and Pitman (1974).

Figures

Figure 88. Leaves and inflorescences of tribe Dimorphandreae A Mora paraensis (Ducke) Ducke (Simon 1663) B Stachyothyrsus staudtii Harms C Burkea africana Hook. D Dimorphandra mediocris Ducke (Simon 4209) E Dimorphandra cuprea Sprague & Sandwith (Farronay 1804) F Dimorphandra parviflora Spruce ex Benth. (Simon 1176) G Dimorphandra mollis Benth. H Dimorphandra pennigera Tul. I Dimorphandra ignea Ducke J Dimorphandra vernicosa Spreng. ex Benth. (Cardoso 3279) K Burkea africana L Dimorphandra gardneriana Tul. (Silva 21). Photo credits A, D, F, G MF Simon B Nicolas Texier (CC-BY-NC-ND- 3.0) C AR Lecuona (CC-BY-NC- 4.0) E, H, I F Javier Farronay Pacaya J D Cardoso K AE van Wyk and S Malan L G Sousa da Silva.

Figure 89. Flowers and fruits of the tribe Dimorphandreae A Dimorphandra cuprea Sprague & Sandwith (Farronay 1804) B Dimorphandra pennigera Tul. C Dimorphandra vernicosa Spreng. ex Benth. (Cardoso 3279) D Dimorphandra ignea Ducke E Stachyothyrsus staudtii Harms F Dimorphandra gardneriana Tul. (Simon 2715) G Dimorphandra macrostachya Benth. (Silva 540) H Dimorphandra cuprea Sprague & Sandwith (Farronay 1804) I Stachyothyrsus staudtii Harms J Burkea africana Hook. K-M Mora paraensis (Ducke) Ducke (K, L Costa 28). Photo credits A, B, D, H F Javier Farronay Pacaya C D Cardoso E Flora of the world F MF Simon G G Sousa da Silva I N Texier (CC-BY-NC-ND- 3.0) J C Sydes (CC-BY-NC- 4.0) K, L J Barbosa Pedrosa Costa M A Rocha Dantas.

Figure 93. Distribution of Burkea based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.