Albizia Durazz.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A pantropical genus of about 150 species (as currently circumscribed - the genus may be redefined in the future). There are six native species in New Guinea (three endemic) and another two widely cultivated species, with two species in the Solomon Islands (one endemic). Species which Verdcourt (1979) placed within Albizia are now considered to be within Archidendropsis or Falcataria.

Morphology General Habit

Trees and shrubs (in New Guinea) to 35 m tall, lacking spines or prickles

Morphology Leaves Stipules

Stipules present, needle-like to linear, caducous

Morphology Leaves

Leaves bipinnate, glands present on leaf rachis and pinnae rachises, leaflets opposite, sessile or petiolulate

Morphology Reproductive morphology Inflorescences

Inflorescences terminal or axillary, glomerules or corymbs which are sometimes aggregated into panicles, small floral bracts present or absent

Morphology Reproductive morphology Flowers

Flowers in outer part of inflorescence bisexual with 1–2 larger central (nectar-holding) staminate flowers, or all flowers bisexual; calyx (4–)5(–7) lobed, valvate in bud; corolla funnel-shaped, (4–)5(–7) lobed, lobes valvate; stamens numerous, fused into a tube at the base, anther glands absent; ovary sessile or stipitate

Morphology Reproductive morphology Fruits

Fruit chartaceous to coriaceous, usually straight, dehiscent or indehiscent, outer layer yellow, black or brown

Morphology Reproductive morphology Seeds

Seeds numerous, flattened, with a pleurogram, not separated within the pod.

Ecology

The native species of Albizia in New Guinea occur in deciduous and semi-deciduous lowland forests, Eucalyptus savannah, open, secondary vegetation in areas with seasonal climate and hill forest up to 1200 m.

Recognition

Albizia chinensis (Osbeck) Merr. is cultivated as a shade tree in coffee plantations, and A. lebbeck (L.) Benth. is cultivated near the coast for fuel and timber. In New Guinea, the diagnostic characters for Albizia include no spines, bipinnate leaves, and distinctive inflorescences with flowers in heads or umbels (or collections of them) with larger staminate flowers in the centre of the inflorescences. The fruits are usually flattened and are mostly dehiscent, but Verdcourt (1979) notes that many species are likely to have indehiscent fruits.

M. Thulin et al. Flora of Somalia Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Trees, sometimes shrubs, the African species unarmed or almost so

Morphology Leaves

Leaves bipinnate

Morphology Reproductive morphology Flowers

Flowers mostly bisexual, in heads (in all Somali species), spikes or spiciform racemes, the central flower often larger and different in form from the others

Morphology Reproductive morphology Flowers Calyx

Calyx and corolla normally 5-lobed

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens numerous, the filaments united below into a tube; anthers eglandular at the apex

Morphology Reproductive morphology Fruits

Pods oblong, straight, flat, usually dehiscent

Morphology Reproductive morphology Seeds

Seeds usually flattened.

Distribution

Some 120–130 species throughout the tropics.

Leguminosae, J. B. Gillett, R. M. Polhill & B. Verdcourt. Flora of Tropical East Africa. 1971

Morphology General Habit

Trees, sometimes shrubs, very rarely climbing (not so in Africa); prickles or spines absent in the African species (except for a very small prickle beneath the node in A. harveyi and that in A. anthelmintica some branchlets may be sharp and spinescent at ends); sharp hooks apparently representing petiole-bases present in a very few extra-African species

Morphology Leaves

Leaves bipinnate; pinnae each with one to many pairs of leaflets

Morphology Reproductive morphology Inflorescences

Inflorescences of round heads, or (not in native African species) spikes or spiciform racemes, pedunculate, axillary and solitary or much more often fascicled, often aggregated near ends of branchlets, which may be lateral and much shortened, sometimes paniculately arranged

Morphology Reproductive morphology Flowers

Flowers hermaphrodite or occasionally ♂ and hermaphrodite; 1–2 central flowers in each head frequently larger, different in form from the others and apparently ♂

Morphology Reproductive morphology Flowers Calyx

Calyx gamosepalous, with normally 5 teeth or lobes (rarely 4, 6 or 7)

Morphology Reproductive morphology Flowers Corolla

Corolla gamopetalous, infundibuliform or campanulate, with normally 5 lobes (rarely 4 or 6, or in A. coriaria and A. tanganyicensis the lobes may be irregularly connate among themselves)

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens numerous (19–50), fertile, their filaments united in their lower part into a slender tube sometimes projecting from, sometimes shorter than the corolla

Morphology Reproductive morphology Fruits

Pods oblong, straight, flat, usually dehiscent, not septate inside, the valves papery to rigidly coriaceous but not thickened or fleshy

Morphology Reproductive morphology Seeds

Seeds usually ± flattened.

Legumes of the World. Edited by G. Lewis, B. Schrire, B. MacKinder & M. Lock. Royal Botanic Gardens, Kew. (2005)

Habit

Trees, shrubs, and lianas

Ecology

Tropical, mostly lowland (sometimes inundated) or low-montane seasonally dry riparian forest, woodland, wooded grassland, bushland and thicket; some restricted to rain forest; others extratropical, rarely in desert foothills, often in secondary vegetation

Distribution

discontinuously circumtropical, most diverse in tropical America (22 spp.), c. 14 spp. in S America, 6 spp. in C America, Mexico and the Caribbean and 2 spp. widespread in the Neotropics; Africa (c. 36 endemic spp.), Madagascar (30 spp., 24 endemic), SE Asia (centred in Malesia [20 spp.], India, Indo-China to China [c. 15 spp., the type species of the genus, A. julibrissin Durazz. is widespread in subtropical to temperate W, C and E Asia]); 1 sp., endemic in N Australia

Note

Albizia has become a dumping ground for unrelated species in the Ingeae and needs to be monographed. Kajita et al. (2001), in their molecular analysis, have reasonable support linking A. julibrissin (the type species of Albizia) with Paraserianthes, thus suggesting a more basally branching position in the tribe for at least one element of Albizia (clustering with the Old World Group in Fig. 27). Luckow et al. (2003) include 8 species of Albizia sens. lat. in their molecular analysis of the Mimosoideae and the genus, as currently circumscribed, is shown to be polyphyletic; three neotropical species form a well-supported group but the Old World species appear as disparate elements scattered amongst other genera of the Ingeae. The spelling 'Albizzia', adopted by Bentham in 1844 and much copied, is incorrect. Rico Arce (1999) reduced Balizia to a synonym of Albizia

Nielsen (1981a) recognised 21 genera in Ingeae (Table 7), although 4 were not given generic names, but were referred to as ‘Gen. A’ to ‘Gen. D’. He recognised the genus Marmaroxylon, although without a generic number, so that the tribe, to the casual observer, appeared to contain only 20 genera. The genus Punjuba appended by Nielsen (1981a) under “genera and species of unknown affinity” is here treated as a synonym of Abarema, following Barneby & Grimes (1996), although we suggest that this may be reinstated as a good genus in the future. Nielsen (1981a) also included Pithecellobium incuriale (Vell.) Benth. as a “species of unknown affinity” but this is now placed in Leucochloron Barneby & Grimes (1996).

Polhill (1994) increased the number of genera of Ingeae to 25 (Table 7). He recognised Nielsen’s ‘Gen. A’ as Paraserianthes I.C.Nielsen, ‘Gen. B’ as Archidendropsis I.C.Nielsen, ‘Gen. C’ as Pararchidendron I.C.Nielsen, and ‘Gen. D’ as Macrosamanea Britton & Rose ex Britton & Killip. He placed Faidherbia in Ingeae for the first time, reinstated Cathormion, Samanea and Chloroleucon, and recognised the monospecific Obolinga Barneby (subsequently subsumed into Cojoba by Barneby & Grimes, 1997). Zapoteca, a segregate of Calliandra described by Hernández (1986), was also added by Polhill (1994). Klugiodendron, recognised by Nielsen (1981a), was considered a synonym of Abarema by Polhill (1994), and Affonsea was placed as a synonym of Inga, a position later confirmed by Pennington (1997).

The present treatment of Ingeae recognises 36 genera (24 of which are New World endemics) and (935)–951–(966) species (Fig. 27). We follow Barneby & Grimes (1997) in placing Obolinga as a synonym of Cojoba. Eight genera: Blanchetiodendron, Ebenopsis, Hesperalbizia, Hydrochorea, Leucochloron, Painteria, Pseudosamanea, and Sphinga, have either been reinstated or described as new since 1994 (Barneby & Grimes, 1996). Paraserianthes section Falcataria was raised to generic status as Falcataria (I.C.Nielsen) Barneby & Grimes (1996). Balizia Barneby & Grimes (1996) is considered a synonym of Albizia following Rico Arce (1999). Guinetia L.Rico & M.Sousa was described as new (Rico Arce et al., 1999, publ. 2000), and Viguieranthus Villiers in 2002.

Clarification of generic relationships within tribe Ingeae still suffers from a paucity of molecular data, partly due to a lack of appropriate material for DNA extraction of the recently described and reinstated genera. Luckow et al. (2000) included four ingoid genera in their analysis of the basal genera of Mimosoideae. These formed a group together with Faidherbia (then still considered a member of tribe Acacieae, although moved to Ingeae by Polhill (1994)). Barneby & Grimes (1996) concentrating on neotropical taxa, divided American ingoids into five informal alliances: the Abarema-, Samanea-, Chloroleucon-, Pithecellobium- and Inga- alliances. Genera of uncertain position within their system included Albizia, Enterolobium and Cedrelinga. Lysiloma was considered as intermediate between tribes Ingeae and Acacieae. Luckow et al. (2003) carried out a phylogenetic analysis of the Mimosoideae using chloroplast DNA sequence data. They treated sixteen of the 36 ingoid genera recognised in this account, including Faidherbia, but concluded that relationships within the Ingeae are generally unresolved and that, with only a few exceptions, clades within the ingoid part of their topology were not strongly supported. Albizia proved to be polyphyletic, supporting the findings of Grimes (1999).

Any new classification of the Ingeae will require sampling of all the genera not included by Luckow et al. (2003) and more extensive sampling of the larger and putatively non-monophyletic genera. Relationships between ingoid genera and the various elements of a polyphyletic Acacia have still to be resolved, although Luckow et al. (2003) have an Acacia subgenus Phyllodineae clade nested within the Ingeae, suggesting that at least part of Acacia sens. lat. (the Australian phyllodinous acacias) might be included within the Ingeae in the future, or that the Ingeae, as currently circumscribed, may have to be broken up into several distinct suprageneric taxa. Such suggestions are premature as 20 ingoid genera, including Abarema, Archidendron, Pithecellobium, Zygia and the largely Madagascan Viguieranthus have not yet been included in molecular analyses.