Acrocarpus Wight ex Arn., Mag. Zool. Bot. 2(12): 547. 1839.

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

Acrocarpus Wight ex Arn., Mag. Zool. Bot. 2(12): 547. 1839.

Figs 7 , 10

Type.

Acrocarpus fraxinifolius Wight & Arn.

Description.

Unarmed evergreen tree, bark pale grey, smooth, brachyblasts absent. Stipules not seen, presumed lacking, at least on mature leaves. Leaves large, bipinnate with a single terminal pinna, leaflets ovate-lanceolate, acuminate (Fig. 7E ). Inflorescences densely flowered, erect, or drooping racemes, or panicles (Fig. 7C ). Flowers bisexual, patent or nodding, 5-merous, sepals and petals green, sepals slightly imbricate, petals slightly longer; disk cupular, completely united with the red hypanthium; androecium haplostemonous, stamens five, exserted from corolla (Fig. 7C ), filaments with basal half green, upper half orange-red, anthers dorsifixed, with introse slits; pollen with a scabrate-punctate sculpture pattern; ovary stipitate, the short style tapered and inflexed to a minute stigmatic pad. Fruits linear to linear-oblong, dehiscent, 2-valved, narrowly winged along upper suture, several- to many-seeded (Fig. 7D ). Seeds ovate or circular, compressed, testa surface with concentric fracture lines, pleurogram lacking.

Chromosome number.

2 n = 24 ( Goldblatt 1981b).

Included species and geographic distribution.

Monospecific ( A. fraxinifolius ), native to South East Asia (from the Indian subcontinent to China and Indo-China) (Fig. 10 ).

Ecology.

Tropical and subtropical broad-leaved rainforest and evergreen gallery forest.

Etymology.

From Greek, acro - (= summit or top) and carpos (= fruit), most probably alluding to the long-stipitate ovaries and fruits.

Human uses.

Timber of A. fraxinifolius (pink cedar tree) is used to make tea boxes, furniture, and plywood; the species is widely grown as an ornamental and is also used for fodder, gums, and bee forage (for honey) ( Lewis 2005b).

Notes.

Acrocarpus was earlier placed in its own Acrocarpus group of tribe Caesalpinieae ( Polhill and Vidal 1981), but the first molecular phylogenetic analyses based on just a few plastid markers ( Doyle et al. 2000; Bruneau et al. 2001; Kajita et al. 2001) suggested the genus was closely related to Ceratonia (then placed in Cassieae ), a relationship that clearly is supported in the phylogenomic analyses of Ringelberg et al. (2022). A large range of flower size throughout its distribution range formerly led to the recognition of two species.

Taxonomic references.

Hou (1996a); Lewis (2005b).

Figures

Figure 7. Flower, fruit, and vegetative characters of tribe Ceratonieae A Arcoa gonavensis Urb., foliage and fruits, Dominican Republic B Tetrapterocarpon geayi Humbert, fruits and part of bipinnate leaf, Madagascar (Du Puy M 410) C-E Acrocarpus fraxinifolius Wight & Arn., India, cultivated tree C inflorescence D dehisced fruits and new flush foliage E part of a bipinnate leaf F-J Ceratonia siliqua L. F tree, Jordan, semi-desert near Petra G fruits, Israel, Mt. Scopus Botanical Gardens, Jerusalem H pistillate flowers, Crete I staminate flowers, Crete J staminate inflorescences, Israel, Jerusalem Botanical Gardens. Photo credits A F Jimenez R. B D Du Puy C-E https: // efloraofindia. com / 2011 / 02 / 01 / acrocarpus-fraxinifolius / E D Valke F, G, J O Fragman-Sapir H, I G Lewis.

Figure 10. Distribution of Acrocarpus based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.