Parkia R. Br. in Denham & Clapperton, Narr. Travels Africa, App.: 234. 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

Parkia R. Br. in Denham & Clapperton, Narr. Travels Africa, App.: 234. 1826.

Figs 164 , 166 , 167

Paryphosphaera H. Karst., Fl. Columb. 2: 7, tab. 104. 1862. Type: Paryphosphera arborea H. Karst. [= Parkia nitida Miq.]

Type.

Parkia africana R. Br., nom. superfl. [≡ Parkia biglobosa (Jacq.) R. Br. ex G. Don (≡ Mimosa biglobosa Jacq.)]

Description.

Unarmed trees or rarely shrubs, 3-40 m, evergreen or rarely deciduous; trunk sometimes buttressed, bark variable. Stipules small, caducous. Leaves alternate, (sub)opposite or clustered at the ends of twigs; pinnae 1-55 pairs, opposite, subopposite or rarely alternate; leaflets 3-110 pairs per pinna, opposite or rarely alternate ( P. biglobosa ), linear to oblong or slightly sigmoid or rarely elliptic and 3-45 × 1-13 mm, or rarely ovate ( P. singularis Miq.) and then to 120 × 75 mm; main-vein central, straight or slightly sigmoid; extrafloral nectaries often present on petiole near the base, elliptic, single or double (or heart-shaped), and sometimes on the rachis between the pinnae, especially in seedlings, small, round. Compound inflorescences of pedunculate capitula arranged in axillary or terminal, short to very long racemes or panicles; principal axis 0.15-5 m long, erect, horizontal, pendent or projecting at all angles, within or beneath the crown to far-extending beyond it; peduncles alternate or (sub)opposite, 1-115 cm long, pendent, erect or projecting at all angles, tough, sometimes thick and robust; 4 caducous bracts enclosing the capitulum in young bud stage. Capitula of 3 types: in sect. Parkia Sphaeroparkia : globose, 1-5 cm diameter, with 120-650 flowers, all fertile, lacking specialised nectar-secreting flowers, red or yellow at anthesis; in sect. Parkia Platyparkia : oblate, 2.7-3.5 × 4-5 cm, with 1060-1325 flowers, these of 2 sorts, those in the middle and at the base fertile, those at the apex modified and nectar-secreting, capitula red; in sect. Parkia Parkia : clavate, subglobose or biglobose, 4-21.5 × 3-8 cm, with 1090-3240 flowers, these of 3 main sorts: fertile ones forming an apical ball, below this a constricted cylinder or depressed ring of nectar-secreting flowers, at the base a zone of staminodial flowers in which the filaments are short to far-projecting and then forming a wide fringe, capitula yellow (sometimes the fringe white), reddish (bright to dull red, pink, orange or purplish), or occasionally bicoloured (red at the base, apical ball yellow). Flowers tubular, each subtended by an obdeltate-spathulate bract, slightly longer than the calyx. Fertile flowers hermaphroditic, functionally staminate, or a mixture; calyx almost bilabiate with 2 large lobes and 3 smaller ones, lobes imbricate in bud (or sub-equal and sub-imbricate in P. ulei (Harms) Kuhlm.); corolla lobes with lower parts variously connate and often adnate to the filament-tube; stamens 10, shortly exserted, filaments usually connate proximally and free distally, anthers basifixed (most species) or dorsifixed (sect. Parkia Sphaeroparkia ), with or without an apical gland; pollen in polyads of 16, 28 or 32 grains, porate, exine granular or with columellae, variously ornamented ( Guinet 1981b; Feuer et al. 1985; Feuer 1986; Luckow and Hopkins 1995), polyads sometimes with a central cavity ( Capucho and Teixeira 2014); nectary disc absent; ovary stipitate, gynoecium reduced in functionally staminate fertile flowers. Nectar-secreting flowers sterile, the basal parts of the calyx, corolla and androecium adnate, much thickened and nectariferous, gynoecium absent (sect. Parkia Parkia ) or modified with the style exserted (sect. Parkia Platyparkia ). Staminodial flowers sterile, the filaments often bearing minute, non-functional anthers, gynoecium absent. Fruits borne on a large, woody, claviform to ellipsoid receptacle with a narrowly terete base (receptacle smaller in sect. Parkia Sphaeroparkia ), stipitate, coriaceous to thick-woody, rarely tough-fleshy ( P. platycephala Benth.), to 60 cm long, indehiscent or dehiscent along the adaxial suture, strap-shaped, narrowly oblong, oblong or rarely terete (e.g., P. biglobosa ), sub-moniliform (e.g., P. filicoidea Welw. ex Oliv. p.p.) or broadly crescent-shaped ( P. multijuga Benth.), sometimes twisted or rarely ± curled, sometimes containing pulp (Paleotropics) or gum (Neotropics), or gum secreted along a laterally enlarged dehiscent adaxial suture (sect. Parkia Platyparkia p.p.). Seeds 6-34 per pod in 1 or rarely 2 rows (sect. Parkia Platyparkia p.p.), flattened-ellipsoid or otherwise, 7-60 mm long; testa hard, thick, dark (rarely soft, green, P. speciosa Hassk.) with a pleurogram, or rarely thin and pleurogram lacking (Figs 164 , 166 ).

Chromosome number.

2 n = 26 (22, 24) ( Santos et al. 2012).

Included species and geographic distribution.

Currently ca. 35 species but more are likely to be recognised as a result of genetic studies (e.g., Ahossou et al. 2020). Species are arranged in three sections: sect. Parkia Parkia (ca. 30 species), pantropical; sect. Parkia Platyparkia [three species: P. paraensis Ducke, P. pendula (Willd.) Benth. ex Walp., P. platycephala ], South and Central America; sect. Parkia Sphaeroparkia (three species: P. multijuga , P. ulei , P. velutina Benoist), South America.

The genus is pantropical (Fig. 167 ) and includes ca. 20 species in the Neotropics, all endemic, from Bolivia and coastal Brazil north to Honduras, plus one African species ( Parkia biglobosa ) naturalised in Haiti (omitted from map), introduced to this and other islands in the West Indies in the 17-18th century; most species are Amazonian and the genus is only rarely found west of the Andes. In mainland Africa: at least three species species, all endemic. In Madagascar: one species, endemic. In the Indo-Pacific: 11 species, including two probably extinct, all endemic, from north-east India eastwards to south-east China, and through South East Asia and Malesia into the Pacific as far east as Ponape and Fiji.

Ecology.

Tropical, predominantly occurring in moist habitats; most species are found in lowland rainforest (occasionally to 1500 m elevation), others grow in riparian forest, fresh-water flooded forest ( várzea and igapó), woodland and wooded grassland (cerrado, savanna), and campinarana. Less common habitats in South America include coastal restinga ( P. bahiae H.C. Hopkins), rocky savanna (cerrado rupestre; P. cachimboensis H.C. Hopkins) and sub-Andean dwarf forest ( P. nana D.A. Neill), and in South East Asia and Malesia, peat swamp forest ( P. paya H.C. Hopkins), tidal streams and Nypa swamp ( P. sherfeseei Merr.), and dry evergreen and/or deciduous forest ( P. leiophylla Kurz, P. sumatrana Miq.).

Etymology.

Named for the Scottish explorer Mungo Park (1771-1806), who investigated the course of the Niger River in West Africa and mentioned what became Parkia biglobosa as the nitta tree in the account of his first expedition to the region ( Park 1799).

Human uses.

In West Africa, the seeds of Parkia biglobosa (African locust bean, néré, nété) are fermented into a widely used pungent condiment (dawadawa, soumbala, iru); the sweet mealy pulp around the seeds is also consumed ( Campbell-Platt 1980; Hall et al. 1997; Termote et al. 2022). In South East Asia, the sulphurous smelling seeds of P. speciosa are eaten fresh or tinned as a vegetable (petai, pete, sator, stinkbean) (e.g., Wiriadinata and Bamroongrugsa 1993; Woon 1995), and the seeds of P. timoriana (DC.) Merr. are consumed in a similar manner in north-east India ( Singh 2022). The pods of P. platycephala are used to feed cattle and goats in north-east Brazil ( Hopkins 1986; Sousa et al. 2015). Numerous traditional medicinal uses have been reported, especially in Africa and Asia, and chemical characteristics suggest much wider medicinal potential (e.g., Saleh et al. 2021).

Notes.

Following Bentham (1841a, 1875), Parkia was traditionally placed with Pentaclethra Benth. in the tribe Parkieae (Wight & Arn.) Endl. because both genera have a calyx with imbricate lobes. Bentham (1875) listed this tribe first (e.g., page 358), presumably to reflect a basal position in his suborder Mimoseae , linking it to the caesalpinioids, but he was equivocal about the affinity of the two genera and sometimes elsewhere in this work he treated them separately. Although it was clear that Parkia and Pentaclethra were unlikely to be closely related ( Bentham 1875; Guinet 1969; Elias 1981b), they were not formally separated until Luckow et al. (2003) and Luckow (2005) placed them in different parts of the Mimoseae , although neither were assigned to a formal group within the tribe. The zygomorphic calyx with imbricate lobes that is so distinctive in Parkia is clearly a derived character, probably related to floral packing in the large bud capitula.

The generic limits of Parkia are unchanged from those of Bentham (1875) and Ducke (1932b, 1949), who devised the sectional classification, slightly modified by Hopkins (1986). Diagnostic characters for the genus include the form of the calyx, the large size of the usually densely-flowered capitula (except P. ulei ), and marked floral differentiation in sections Parkia and Platyparkia . The capitulum in sect. Parkia Platyparkia , with nectar-secreting flowers at the apex (Fig. 164K ), is unique in Mimoseae . The fruits of two of its species ( P. paraensis , P. pendula ), in which copious sticky gum is secreted along a laterally enlarged dehiscent adaxial suture, may also be unique (Fig. 164L ). The capitula of the species in sect. Parkia Parkia that have long staminodes projecting from their basal flowers (Fig. 166A, E, F, G ) are superficially similar to those of Dichrostachys cinerea (L.) Wight & Arn., and the pale yellow capitula of P. ulei resemble those of some other Mimoseae (e.g., Leucaena Benth.) in size, colour and arrangement.

Parkia is one of the most variable genera in the Mimoseae . However, despite variation in the structure of the capitula, in the morphology of the flowers, fruits and seeds, in the type of germination (phaneroepigeal, phanerogeal or cryptohypogeal) and in pollen sculpturing ( Hopkins 1986; Luckow and Hopkins 1995), it has been shown to be monophyletic ( Luckow and Hopkins 1995; Koenen et al. 2020a; Oliveira et al. 2021; Ringelberg et al. 2022). The cradle of the genus is the Americas ( Oliveira et al. 2021), and the greatest morphological diversity and species richness also occur here. Inter-continental trans-oceanic dispersal has most likely been facilitated by an ability in some species (e.g., P. discolor Spruce ex Benth.) of the pods to float and the seeds to withstand prolonged immersion in salt water ( Hopkins 1986).

This genus has a number of unusual characters compared with others in this and closely related clades. Some appear idiosyncratic, such as the opposite leaves in a few Neotropical and one Asian species, and the lack of root nodulation. However, many of its distinctive features can be related to reproductive biology, including the sometimes very elongated compound inflorescence axes, tough and sometimes long, pendent or erect peduncles, capitula commonly composed of very numerous, relatively large flowers, foetid floral odours, and crepuscular/nocturnal anthesis (diurnal only in P. ulei ). Sections Parkia and Platyparkia are pollinated by bats that typically land on the capitula to lap nectar (rather than by hovering to feed), belonging to the Phyllostomidae in the Americas and the Pteropodidae in Africa, Asia and the Pacific; various non-volant mammals, insects including bees, and birds, are occasional pollen vectors and nectar and/or pollen thieves (e.g., Pettet 1977; Grünmeier 1990; Birkinshaw and Colquhoun 1998; Hopkins 1998; Piechowski et al. 2010; Lassen et al. 2012; Kobayashi et al. 2021). The smaller, less specialised capitula of sect. Parkia Sphaeroparkia are insect-pollinated ( P. ulei : diurnal bees; P. velutina : nocturnal bees; P. multijuga : diverse small insects including beetles and thrips) ( Hopkins et al. 2000; Chaves 2015). Partial self-incompatibility has been demonstrated in P. biglobosa ( Lassen et al. 2012).

The wide range in fruit characters is reflected in a variety of dispersal mechanisms. Seed-dispersers include chimpanzees, various Neotropical and Paleotropical monkeys and perhaps birds, and for fruits that fall to the ground readily at maturity, large rodents ( Parkia multijuga , Fig. 166N ), ruminants, and water ( P. discolor ) ( Hopkins 1983; Hopkins and Hopkins 1983; Bertolani and Pruetz 2011). In Africa, the sweet pulp around the seeds (Fig. 166I , P. bicolor ) and to a lesser extent the seeds themselves are attractive to primates. Amongst Neotropical monkeys, marmosets and tamarins ( Callitrichidae ) in particular consume the gum that is found inside the indehiscent fruits of many species in sect. Parkia Parkia or exuded from the dehiscent ones of P. pendula ( Peres 2000). Some Callitrichidae also consume exudates from gouging the bark (e.g., Ramírez et al. 1977). Insect seed-predators include moths and, particularly in the Americas, bruchid beetles ( Chrysomelidae : Bruchinae ) ( Hopkins 1984).

Taxonomic references.

Ducke (1949); Hagos (1962); Hopkins (1983, 1986, 1994); Nielsen (1981b, 1985a, 1992); Villiers (2002).

Figures

Figure 164. Morphological features of Anadenanthera (A-I) and Parkia sect. Platyparkia (J-L) A A. colubrina (Vell.) Brenan capitulum cut in half, at anthesis B capitula at anthesis and in bud C shrub D Anadenanthera sp. foliage and petiolar nectary E A. colubrina mature pods F mammillate projections on trunk G dehisced pods H A. peregrina var. falcata (Benth.) Altschul mammillate trunks I A. peregrina (L.) Speg. var. peregrina trees with smooth trunks J Parkia pendula (Willd.) Benth. ex Walp. (Hopkins & Hopkins 273), Neotropics, tree crown K capitulum at anthesis, nectar exuding from apical flowers L pods with enlarged adaxial suture secreting gum into which the seeds have fallen. Photo credits A-I RT Queiroz https: // rubens-plantasdobrasil. blogspot. com / J-L MJG Hopkins and HCF Hopkins.

Figure 166. Morphological features of Parkia sect. Parkia (A-L) and sect. Parkia Sphaeroparkia (M, N) A P. bicolor A. Chev. pendent capitulum approaching anthesis, Korup National Park, Cameroon B P. biglobosa (Jacq.) R. Br. ex G. Don pendent capitulum cut in half, Ibadan, Nigeria C P. decussata Ducke erect capitulum at anthesis, Neotropics (Hopkins & Hopkins 237) D P. timoriana (DC.) Merr. pendent capitulum, South East Asia (H. C. F. Hopkins 634) E P. gigantocarpa Ducke pendent capitulum and another cut in half, shortly post-anthesis, finger ring gives scale, Neotropics (Hopkins & Hopkins 298) F P. igneiflora Ducke pendent capitulum near anthesis, Neotropics (Hopkins & Hopkins 230) G P. speciosa Hassk., capitula at anthesis, Temburong, Brunei H P. discolor Spruce ex Benth. indehiscent pods nearing maturity, Neotropics (Hopkins & Hopkins 264) I, J P. bicolor I ripe indehiscent pod with yellow valves containing orange pulp, Bero Mts, Guinea-Conakry J immature pods, Korup National Park, Cameroon K P. cachimboensis H. C. Hopkins dehiscent pods lacking gum, the seeds attached by their funicles, Serra do Cachimbo, Brazil L P. igneiflora var. aurea Ducke vel aff. erect compound inflorescence axes projecting above the tree crown bearing pendent yellow capitula on short pendent peduncles, Cachoeira Berro d'Agua, AM, Brazil M, N P. multijuga Benth. M capitula at anthesis and in bud, Trombetas, Brazil N old pod from ground plus seeds, INPA, Manaus, Brazil. Photo credits A R Gruenmeier B HCF Hopkins C-F, H, K, N MJG Hopkins and HCF Hopkins G I Nielsen I M Cheek J X van der Burgt L L Mello M unknown.

Figure 167. Distribution of Parkia based on quality-controlled digitised herbarium records. The presence of the West African P. biglobosa (Jacq.) R. Br. ex G. Don in Haiti, where it is naturalised, is not shown. See Suppl. material 1 for the source of occurrence data.