Albizia Durazz., Mag. Tosc. 3(4): 13. 1772.

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

Albizia Durazz., Mag. Tosc. 3(4): 13. 1772.

Figs 257 , 258 , 259 , 260 , 261

Sassa Bruce ex J.F. Gmel., Syst. Nat., ed. 13[bis]. 2(2): 1038. 1792. Type: Sassa gummifera J.F. Gmel. [≡ Albizia gummifera (J.F. Gmel.) C.A. Sm.]

Besenna A. Rich., Tent. Fl. Abyss. 1: 253. 1847. Type: Besenna anthelmintica A. Rich. [≡ Albizia anthelmintica (A. Rich.) Brongn.]

Arthrosprion Hassk., Retzia i: 212. 1855. Type: Arthrosprion stipulatum (DC.) Hassk. [≡ Acacia stipulata DC. (= Albizia chinensis (Osbeck) Merr.)]

Cathormion (Benth.) Hassk., Retzia 1: 231. 1855. Type: Cathormion umbellatum (Vahl) Kosterm. [≡ Albizia umbellata (Vahl) E.J.M. Koenen]

Parasamanea Kosterm., Organ. Natuurw. Onderz. Indonesië 20: 11. 1954. Type: Parasamanea landakensis (Kosterm.) Kosterm. [≡ Albizia rosulata subsp. Parasamanea landakensis landakensis (Kosterm.) I.C. Nielsen]

Serialbizzia Kosterm., Organ. Natuurw. Onderz. Indonesië 20: 15. 1954. Type: Serialbizzia acle (Blanco) Kosterm. [≡ Albizia acle (Blanco) Merr.]

Parenterolobium Kosterm., Organ. Natuurw. Onderz. Indonesië 20: 19. 1954. Type: Parenterolobium rosulatum (Kosterm.) Kosterm. [≡ Albizia rosulata Kosterm.]

Type.

Albizia julibrissin Durazz.

Description.

Small to very large trees to 45 m with large rounded or flat-topped spreading crown or rarely shrubs, and then sometimes scandent or lianescent, or a liana to 45 m [ Albizia corniculata (Lour.) Druce], usually unarmed except for a few species with spinescent shoots [ A. anthelmintica Brongn., A. moniliforme (DC.) F. Muell. and A. umbellata (Vahl) E.J.M. Koenen] or prickles/hooks ( A. corniculata , A. myriophylla Benth. and A. rufa Benth., these species with a scandent shrubby or lianescent habit) or recurved thorn-like stipules (in A. pedicellata Baker ex Benth.), short shoots or brachyblasts sometimes present. Stipules small linear to triangular, usually caducous, sometimes larger, rounded, leaf-like and persistent or caducous, or recurved, thorn-like and caducous in one species ( A. pedicellata ). Leaves bipinnate, macro- or microphyllidinous, with 1-25 pairs of pinnae, the petiole with an extrafloral nectary and usually with further nectaries between the apical pairs of pinnae and leaflets; leaflets 1-47 pairs, small and linear to large and elliptical, rounded or rhombic, frequently (especially in microphyllidinous species) the midrib displaced to either side of the leaflet blade and often several additional strong veins starting from the leaflet base (i.e., palmate-pinnate venation), in the macrophyllidinous species often with pinnate venation, base oblique to equal, apex rounded, acute or mucronate. Inflorescence units sub- or hemiglobose, often corymbiform, or sometimes globose, capitula, usually aggregated into terminal or axillary panicles with the leaves suppressed, otherwise fascicular in leaf-axils. Flowers 5-merous,mostly white or cream, or often bicoloured with pink to red upper half of stamens, sessile or often especially the peripheral flowers pedicellate, dimorphic or sometimes monomorphic, often the central flower enlarged and more robust with a broad cupular nectariferous base and longer staminal tube; calyx slenderly campanulate or funnel-shaped; corolla funnel-shaped; stamens numerous, fused into a tube not or slightly exserted beyond the corolla lobes, in terminal flowers usually well-exserted and in some species the tube very long in all flowers and exserted well beyond the corolla lobes, anthers dorsifixed, eglandular; pollen shed in 16-celled flat disk-shaped polyads (but only a few species have been studied); ovary sessile or shortly stipitate, the style approximately the same length as the stamens or extending slightly beyond the anthers, stigma funnel-shaped. Fruit usually straight, flat, papery, dehiscent or inertly dehiscent along both sutures or indehiscent, or straight or slightly curved, indehiscent and thick woody (in several Madagascan species), or straight to curved or twisted and moniliform (in A. atakataka Capuron and A. commiphoroides Capuron) or straight to twisted, septate, lomentiform, breaking up into one-seeded segments (in A. moniliforme and A. umbellata ) or straight or curved, septate and coriaceous [in A. acle (Blanco) Merr.] or contorted, septate and woody [in A. rosulata (Kosterm.) I.C. Nielsen and A. dolichadena (Kosterm.) I.C. Nielsen] tardily breaking up into articles. Seeds elliptical to rounded, laterally compressed, usually with a large subcircular or narrowly elliptic closed pleurogram, or a small, rounded deltoid to subcircular pleurogram in the upper half of the seed, or sometimes a U-shaped pleurogram open towards the hilum.

Chromosome number.

2 n = 26, one species ( A. polyphylla Fourn.) is reported to be an octoploid with 2 n = 104 ( Darlington and Wylie 1956).

Included species and geographic distribution.

ca. 90 species, in Africa, Madagascar, (sub)tropical Asia, Malesia, Australia and several Pacific Islands (Fig. 261 ). Centres of diversity are in South East Asia and in the East African Great Lakes region and Madagascar.

Ecology.

Albizia has a wide ecological range with species found in coastal, riverine and swamp forests, terra firme rainforest, seasonally dry deciduous forest, savannas and (sub)montane forest. Although most species of Albizia are tropical, a few Asian species, including the type species A. julibrissin Durazz., are mildly frost-tolerant and extend into the subtropical and warm temperate zone, as well as cooler (sub)montane regions. Most species are medium sized trees, in either primary vegetation or as coloniser species in secondary vegetation, with a few species occurring as large canopy trees while some of the semi-arid species remain small shrubby trees and a few Asian species are scandent shrubs to lianas at forest edges and disturbed sites or in primary and secondary forests (Fig. 257A-E ).

Etymology.

Named for Filippo degli Albizzi, an 18th century Italian naturalist from the wealthy Albizzi family of Tuscany, who reportedly brought seeds of the species from Constantinople to Florence in 1749. The spelling “Albizzia” has historically been used and would be the correct spelling given the Albizzi family name, however, in the original publication the spelling Albizia was used and hence this has to be considered the correct name ( Nielsen 1979). This is particularly confusing since the recently reinstated Pseudalbizzia was spelled with two ‘z’ in the original publication.

Human uses.

The wood of several species is used for various purposes, including house construction, furniture, boat building, musical instruments, as well as for firewood and charcoal. Several species are planted as shade trees in coffee and tea plantations and for soil improvement, and as street trees or ornamentals in parks and gardens (Fig. 258B ). Some species yield a gum that is similar to gum arabic, and dyes and tannins are extracted from the bark, particularly in A. lebbekoides (DC.) Benth. The bark of A. saponaria Blume ex Miq. and several other species contains saponin and can be used as a substitute for soap. The bark of several species is used as a fish poison and shows insecticidal activity. Leaves and seeds of some species are used for food or as animal fodder. Leaves, bark and roots of various species are used medicinally, e.g., A. adianthifolia (Schumach.) W. Wight, A. amara (Roxb.) Boivin and several other African species with numerous applications in traditional medicine across Africa ( Louppe et al. 2008) and the bark of A. anthelmintica is used against tapeworm.

Notes.

Albizia was described by Durazzini (1772) from specimens of A. julibrissin , a native of warm temperate and subtropical Asia from Turkey to Japan, that were planted in Florence. The genus has since known a turbulent taxonomic history, having been very broadly circumscribed in the past when it was considered a “dustbin” genus in which to place species that had no clear affinity to other existing ingoid genera. Nielsen (1979, 1985b), in a series of publications, delimited the genus in the Asian, Australian and Pacific region, and transferred several species that were described or previously included in Albizia to the genera Archidendron F. Muell. ( Nielsen et al. 1984a), Archidendropsis I.C. Nielsen, Paraserianthes I.C. Nielsen, Pararchidendron I.C. Nielsen and Serianthes Benth. ( Nielsen et al. 1983a, 1983b, 1984b; Archidendron clade, page 404). He considered Cathormion (Benth.) Hassk. a monotypic genus distinct from Albizia ( Nielsen 1979, 1992). Although Cathormion has now been included in Albizia ( Koenen et al. 2020a), Nielsen’s taxonomy is otherwise mostly well-supported by phylogenies ( Koenen et al. 2020a; Ringelberg et al. 2022; Brown et al. 2022; Demeulenaere et al. 2022; Koenen, unpubl. data). The African species are comprehensively but patchily covered by regional and national flora treatments across the continent (e.g., Hutchinson and Dalziel 1958; Brenan 1959, 1970; Villiers 1989; Thulin 1993). Five African species that had previously been included in Albizia by some authors while placed in Cathormion and/or Samanea (Benth.) Merr. by others, are now accommodated in either Hydrochorea Barneby & J.W. Grimes (Soares MVB et al. 2022; Jupunba clade, page 437) or Osodendron E.J.M. Koenen ( Koenen 2022b; Inga clade, page 466). The Madagascan species were reviewed by Villiers (2002), but for several species incomplete material was available at the time and the genus remains relatively poorly known on the island and in need of further taxonomic study. Barneby and Grimes (1996) monographed the Albizia species of the Americas, but these species have now been shown to be more closely related to the Abarema alliance ( Koenen et al. 2020a; Ringelberg et al. 2022) and have been transferred to a reinstated Pseudalbizzia Britton & Rose ( Peraza et al. 2022) and included in the Jupunba clade (page 437), with the exception of Albizia carbonaria Britton, which is now placed in Pseudosamanea Harms ( Koenen 2022a; see page 434).

Following these recent taxonomic updates, the species that remain accommodated in Albizia under the circumscription that is presented here, have been shown to form a monophyletic group in preliminary phylogenomic analyses that sampled 75 of the ca. 90 species (Koenen et al., unpubl. data; Ringelberg et al. 2023; Suppl. material 2). These preliminary results show that the genus consists of four geographically structured clades: (1) a clade that includes the type species A. julibrissin and ca. 38 species that are found from Turkey in the West across continental Asia and Malesia to Australia and some Pacific islands in the East; (2) Albizia sect. Zygia Benth. is a small clade of 10 species that is widespread across sub-Saharan Africa and Madagascar and in which the stamens are characteristically fused into a tube for most of their length with short radially spreading free parts of the filaments (Fig. 259A, B ); (3) a clade with ca. 11 species found across Africa; and (4) a clade of ca. 31 species predominantly distributed in Madagascar, but including six species from continental Africa of which one species ( A. amara ) extends into continental Asia in India and Sri Lanka. These four clades are each well-supported as monophyletic, but the relationships among them are not well-resolved.

Nearly all species of Albizia are fundamentally trees (Fig. 257A, B, D, E ), although they may become multi-stemmed and shrub-like presumably due to resprouting after the main stem has become damaged. Three Asian species, Albizia corniculata , A. myriophylla and A. rufa , that have a scandent shrubby or lianescent habit (sometimes growing into a liana to 45 m), form an exception (Fig. 257C ). These species were placed in the informal " Albizia corniculata group" by Nielsen (1985b). Interestingly, these three species form a grade to a small clade of tree species (Koenen et al., unpubl. data), suggesting the lianescent habit evolved once and was subsequently reversed once in the descendant lineage leading to the small tree species clade. These three lianescent species have an unusual form of armature where a recurved prickle or hook is found beneath the leaf base or leaf scar. The African species A. anthelmintica Brongn. and the South East Asian and Australasian species A. moniliformis and A. umbellata often have spinescent shoots, a type of armature that is common among Mimoseae and has evolved multiple times ( Ringelberg et al. 2022). Furthermore, the Malesian species A. pedicellata has recurved thorn-like stipules that are caducous. Otherwise, all other species are reported as being unarmed.

As in many Mimoseae genera, the bipinnate leaves vary widely in the numbers of pinna and leaflet pairs per leaf, as well as the size and shape of leaflets (Fig. 258A-I ). In many species, the midrib is displaced to the upper side of the leaflets, as also occurs in the two other genera in the Albizia clade. Most species are characterised by dimorphic flowers in each unit inflorescence (Fig. 259A-D, F-H ), with one or a few central flowers enlarged and more robust with a nectariferous base, these sessile with peripheral flowers (sub)sessile or often pedicellate. Especially in the African section Albizia Zygia , the combination of a nectariferous central flower with peripheral flowers with very long staminal tubes (Fig. 259A, B ) are unusual and unlike any other Mimoseae genus. Homomorphic inflorescences (Fig. 259E, I ) are also found in a smaller number of species that are phylogenetically scattered across clades 1, 3 and 4 (Suppl. material 2). The unit inflorescences can be arranged in slender efoliate terminal or axillary panicles such as in the type species A. julibrissin , or emerging from axillary fascicles. Dense clustering of inflorescences at the apices of branchlets when species are in full bloom means that some species have been used as ornamentals, with especially A. julibrissin having been planted extensively in gardens and parks in (warm) temperate regions around the world (Fig. 258B ).

Most species have straight flat papery fruits inertly dehiscent along both sutures or indehiscent, that are sometimes slightly swollen around the seeds, but markedly different fruits are found in some Asian and Madagascan species, these placed in clades 1 and 4, respectively (Suppl. material 2):

First, the species A. moniliformis (Indonesia to Australia) and A. umbellata (continental South East Asia) that are placed in clade 1, have septate lomentiform fruits (Fig. 260C ) that break up into one-seeded segments. These two species have previously been treated as subspecies of the type species of the genus Cathormion , which at one point was considered a pantropical genus in which several unrelated lomentiform species were placed, and which have now all been transferred to Chloroleucon Barneby & J.W. Grimes ( Barneby and Grimes 1996), Hydrochorea (Soares MVB et al. 2022), Osodendron ( Koenen 2022b) and Pseudalbizzia ( Peraza et al. 2022), except for the type species C. umbellatum which is now placed in Albizia and hence the name Cathormion is synonymised with this genus ( Koenen et al. 2020a).

Secondly, the five Asian species that Nielsen (1985b) referred to the informal " Serialbizzia group", also placed in clade 1, have woody to coriaceous fruits that are usually septate and either straight ( A. acle , A. attopeuensis (Pierre) I.C. Nielsen and A. splendens Miq.) or contorted ( A. dolichadena and A. rosulata ), with especially the woody contorted fruits of the latter two species prone to tardily fragmenting into 1-seeded articles. The Serialbizzia group is not monophyletic, with A. attopeuensis with coriaceous valves not grouping with the woody-valved species (but A. splendens , that also has coriaceous valves, has not been sampled in phylogenies as of yet; Koenen et al., unpubl. data). Another species in clade 1, A. salomonensis C.T. White ex F.S. Walker has very large sub-woody fruits and has been placed in Serialbizzia in the past but is not closely related to the other Asian woody-valved species.

Thirdly, two unusually densely branched (Figs 257A , 258F ) species placed in clade 4, endemic to the semi-arid scrub region of south-western Madagascar, A. atakataka and A. commiphoroides , have (sub)moniliform indehiscent pods that may become fragmented after having been shed, and are strongly constricted between the seeds, especially in the latter species (Fig. 260F ).

Finally, seven of the ca. 24 Albizia species endemic to Madagascar, all also placed in clade 4, have thick woody indehiscent fruits (Fig. 260G ).

Taxonomic references.

Bentham (1985); Brenan (1959, 1970 [9]); Brummitt (1970); Hutchinson and Dalziel (1958); Koenen et al. (2020a: appendix 2); Nielsen (1979, 1981a, 1985b, 1992); Nielsen et al. (1983: p. 43-45); Thulin (1993); Villiers (2002).

Figures

Figure 257. Habit diversity of the Albizia clade A Albizia atakataka Capuron, a densely branched small tree in dry thorn-scrub in south-western Madagascar B A. anthelmintica Brongn., a small tree flowering before the leaves appear, in semi-arid regions of southern Africa C A. corniculata (Lour.) Druce, a scandent shrub or liana in humid forests in continental South East Asia, the Philippines and northern Borneo D Albizia sp. (Koenen 434), a large tree in semi-deciduous forest in north-western Madagascar E A. tanganyicensis Baker f., a small tree in dry savanna woodland and (sub) montane grassland in southern and eastern Africa F Boliviadendron bolivianum (C. E. Hughes & Atahuachi) E. R. Souza & C. E. Hughes (Hughes 2608), a tree in seasonally dry tropical forest in Bolivia G Enterolobium cyclocarpum (Jacq.) Griseb. (Hughes 1254) H trunk of E. contortisiliquum (Vell.) Morong, both trees of seasonally dry and semi-deciduous forests of South and Central America. Photo credits A, D, E, H E Koenen B A Dreyer, www. africanplants. senckenberg. de C Biobank Lantauhk (Hong Kong), iNaturalist (https: // www. inaturalist. org / photos / 66503444) F, G CE Hughes.

Figure 258. General and vegetative morphology of the Albizia clade A Albizia chinensis (Osbeck) Merr., flowering branch (Koenen 190) B cultivated A. julibrissin Durazz., flowering branch C A. glaberrima Benth., foliage and inflorescences D A. zygia J. F. Macbr., flowering branch E A. polyphylla Fourn., finely bipinnate foliage (Koenen 256) F A. atakataka Capuron, dense branching with the leaves arising from brachyblasts (Koenen 229) G A. laurentii De Wild., flower buds and quadrifoliolate bipinnate leaves H A. tanganyicensis Baker f., leaf I A. gummifera C. A. Sm., detail of pinna with rhombic leaflets J Boliviadendron bolivianum (C. E. Hughes & Atahuachi) E. R. Souza & C. E. Hughes, foliage and flowers (Hughes 2423) K Enterolobium contortisiliquum (Vell.) Morong, foliage L E. timbouva Mart., detail of pinna. Photo credits A, E, F, H E Koenen B M Fitzgerald C G Baumann D W Dijkstra G D Harris I I Dinter J CE Hughes K A Martinez Ponte, iNaturalist (https: // www. inaturalist. org / photos / 195358543) L F Acaz Sonntag, iNaturalist (https: // www. inaturalist. org / photos / 216600814) B-D, G, I www. africanplants. senckenberg. de.

Figure 259. Inflorescences of the Albizia clade A Albizia grandibracteata Taub., strongly dimorphic capitula (Koenen 159) B A. mainaea Villiers of Albizia section Zygia, strongly dimorphic capitula (Koenen 426) C A. chinensis (Osbeck) Merr., more cryptic dimorphic capitula (Koenen 190) D A. lebbeck (L.) Benth., more cryptic dimorphic capitula E A. procera (Roxb.) Benth., homomorphic capitula F A. anthelmintica Brongn., dimorphic capitula G A. atakataka Capuron, dimorphic capitula (Koenen 229) H A. forbesii Benth., dimorphic capitula I A. zimmermannii Harms, homomorphic capitula J Boliviadendron bolivianum (C. E. Hughes & Atahuachi) E. R. Souza & C. E. Hughes, homomorphic capitula (Hughes 2423) K Enterolobium cyclocarpum (Jacq.) Griseb., homomorphic capitula (Hughes 1254). Photo credits A-C, G, H E Koenen D M Schmidt E R Cumming, iNaturalist (https: // www. inaturalist. org / photos / 168379143) F I Dinter I C Boucher Chisale J, K CE Hughes D, F, I www. africanplants. senckenberg. de.

Figure 260. Fruits of the Albizia clade A Albizia lebbeck (L.) Benth., flat papery fruits and B A. procera (Roxb.) Benth., flat papery fruits C A. moniliformis (DC.) F. Muell., lomentaceous fruits D A. ferruginea (Guill. & Perr.) Benth., flat papery fruits (Harris 9726) E A. boivinii Fourn., flat papery fruits (Koenen 376) F A. commiphoroides Capuron, moniliform fruits G of A. masikororum R. Vig., thick woody fruits H Boliviadendron bolivianum (C. E. Hughes & Atahuachi) E. R. Souza & C. E. Hughes, flat papery fruits (Hughes 2423) I Enterolobium contortisiliquum (Vell.) Morong, thick coriaceous ear-shaped fruits (Queiroz 15579) J E. monjollo (Vell.) Mart., thick coriaceous ear-shaped fruits (Lima 7911). Photo credits A G Baumann www. africanplants. senckenberg. de B I Cowan, iNaturalist (https: // www. inaturalist. org / photos / 54408314) C R Cumming, iNaturalist (https: // www. inaturalist. org / photos / 200251197) D D Harris www. africanplants. senckenberg. de E, I, J E Koenen F Desire Ravelonarivo, Tropicos (https: // www. tropicos. org / ImageFullView. aspx? imageid = 100291301) G SE Rakotoarisoa, iNaturalist (https: // www. inaturalist. org / photos / 3113769) H CE Hughes.

Figure 261. Distribution of Albizia based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.