1. Family: Fabaceae Lindl.
    1. Mezoneuron Desf.

      1. This genus is accepted, and its native range is Tropical & Subtropical Old World to SW. Pacific, Hawaiian Islands.

    [LOWO]

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

    Note

    Polhill & Vidal (1981) divided the Caesalpinieae into 8 informal generic groups: the Gleditsia group (2 genera), the Acrocarpus group (monogeneric), the Sclerolobium group (3 genera), the Peltophorum group (13 genera), the Caesalpinia group (16 genera), the Poeppigia and Pterogyne groups (both monogeneric) and the Dimorphandra group (10 genera). They commented that the tribe is “a remarkable mixture of relics and complexes of relatively recent speciation, providing many pitfalls for formal systematics and biogeographical interpretations”. Polhill (1994) added a ninth informal group, the monogeneric Orphanodendron group, and placed Cordeauxia as a synonym of Stuhlmannia (both genera recognised in the present treatment) so that the total of 47 genera in the tribe remained unchanged. Within the tribe, Parkinsonia (including Cercidium), Conzattia and Lemuropisum were moved from the Caesalpinia group to the Peltophorum group (Polhill, 1994) in agreement with the subsequently published works of Lewis & Schrire (1995) and Du Puy et al. (1995b).

    Since 1994 several studies have cast new light on intergeneric relationships within the Caesalpinieae, necessitating the restructuring of some of the nine informal generic groups presented by Polhill (1994). As pointed out in the introduction to tribe Cassieae, the genus Ceratonia has been removed from that tribe to the Caesalpinieae, and Poeppigia has been removed from the Caesalpinieae to the Cassieae (for further detail see discussion under each genus). In the rbcL phylogeny of Doyle et al. (1997) the Caesalpinieae, as traditionally circumscribed, was shown to be paraphyletic with members scattered throughout a clade which also included genera of the Cassieae and one mimosoid genus. The molecular analysis of Kajita et al. (2001) also found the Caesalpinieae to be non-monophyletic. In the molecular analysis of Bruneau et al. (2001) some of the informal generic groups of Polhill (1994) were supported as monophyletic but the tribe as a whole was clearly demonstrated to be paraphyletic. With regard to intergeneric relationships, Pterogyne resolved as sister to a Caesalpinia group clade; Batesia and Vouacapoua fell outside a core- Peltophorum group, and the Dimorphandra group was clearly shown to be a diverse assemblage of genera, many of which share certain characteristics with the Mimosoideae, specifically with members of tribe Mimoseae (Bruneau et al., 2001). Erythrophleum was sister to a clade that comprised the majority of the Mimosoideae sampled, and Pachyelasma was sister to the two mimosoid genera Pentaclethra and Calpocalyx. Herendeen et al. (2003a) in a combined molecular-morphological analysis which expanded on the study of Bruneau et al. (2001), presented an ‘Umtiza clade’ containing Gymnocladus and Gleditsia (the two members of Polhill and Vidal’s Gleditsia Group), Umtiza (traditionally included in tribe Detarieae), Tetrapterocarpon (from the Dimorphandra Group), Acrocarpus (the sole genus of the Acrocarpus Group), and Ceratonia (from subtribe Ceratoniinae in tribe Cassieae). This new generic grouping raises some fascinating phytogeographical questions (see Schrire et al., pages 21–54, this volume). Pterogyne resolved as sister to a Chamaecrista-Senna clade (of tribe Cassieae) a relationship worthy of further study; Batesia and Vouacapoua again fell outside the core-Peltophorum group; Dimorphandra grouped with Mora as sister to all Mimosoideae, and Pachyelasma grouped with Erythrophleum as sister to the Dimorphandra-Mimosoideae clade. In the phylogenetic investigation of Haston et al. (2003), the Peltophorum group of Polhill (1994) was non-monophyletic but there was support for a core-Peltophorum group comprising Peltophorum, Parkinsonia, Schizolobium, Conzattia, Delonix, Lemuropisum, Colvillea and Bussea. Pterogyne resolved as sister to a clade containing Haematoxylum and Cordeauxia (both of the Caesalpinia group), thus supporting the earlier findings of Bruneau et al. (2001) rather than those of Herendeen et al. (2003a). Haston et al. (submitted) have further refined the relationships of the non core-Peltophorum group genera. They place Arapatiella and Jacqueshuberia with Tachigali in a newly defined Tachigali group and find strong molecular support for associating Batesia with Recordoxylon and Melanoxylon in a new Batesia group. Moldenhawera is placed in its own monogeneric group sister to a Tachigali group–core-Peltophorum group–Dimorphandra group–Mimosoideae clade. In an analysis testing the monophyly of the Umtiza clade (Herendeen et al., 2003b), Arcoa (traditionally of the Dimorphandra group) from the Dominican Republic was added to the group of genera in that clade.

    Without doubt, the genus with the greatest taxonomic and nomenclatural complexity within the Caesalpinieae is the type genus Caesalpinia, which in its broadest sense comprises c. 140 spp. and contains 25 generic names in synonymy. Of these 140 species, 12–15 predominantly Asian taxa have still to be included in molecular studies and cannot yet be assigned to any generic segregate recognised in this treatment (see notes under Caesalpinia L.). Studies by Lewis & Schrire (1995), Simpson & Miao (1997), Lewis (1998), Simpson (1998, 1999), Simpson & Lewis (2003) and Simpson et al. (2003), have clearly demonstrated that Caesalpinia, as traditionally circumscribed, is polyphyletic. In this treatment Hoffmannseggia is recognised as distinct following Simpson & Miao (1997), Simpson (1999) and Ulibarri (1979, 1996); Pomaria is also segregated from Caesalpinia sens. lat. following Simpson (1998) and Simpson & Lewis (2003). The genera Coulteria, Erythrostemon, Guilandina, Libidibia, Mezoneuron, Poincianella and Tara are also reinstated following the findings of Lewis & Schrire (1995), Lewis (1998), Simpson et al. (2003), Lewis & Bruneau (unpublished), Lewis & Lavin (unpublished) and Sotoyo (unpublished). Caesalpinia sens. strict. is, in consequence, reduced to a genus of 25 species.

    The Caesalpinieae as presented here contains 56 genera and (423)–436–(448) species (Fig. 23). Thirty two of the genera contain 3 or fewer species each, with 23 monospecific (a second species of Orphanodendron has apparently been discovered in Colombia, but is, as yet, undescribed [Cogollo Pacheco, pers. comm., 2002]). A new genus, tentatively named as Heteroflorum by Sousa & Delgado (1993), but not yet formally published, is a monospecific Mexican endemic closely related to Conzattia. It is not dealt with here. The informal generic groups of tribe Caesalpinieae presented by Polhill & Vidal (1981) and Polhill (1994) are retained in part in Fig. 23 which accompanies this treatment, but there are some noteworthy exceptions. The Gleditsia and Acrocarpus groups are both subsumed into the ‘Umtiza clade’; Diptychandra is rejected from the Sclerolobium group which now becomes the Tachigali group and includes Arapatiella and Jacqueshuberia; Poeppigia is moved to the Cassieae; several genera are removed from the Peltophorum group leaving a core of nine related genera (if Heteroflorum is included); Batesia, together with Recordoxylon and Melanoxylon constitutes a new Batesia group based on the work of Haston et al. (submitted). Moldenhawera is placed in its own group as its generic relationships are currently unclear (Haston et al., submitted). The Caesalpinia group increases in size from 12 to 21 genera. Five genera are currently too poorly known for them to be placed with confidence: Campsiandra, Chidlowia, Diptychandra, Orphanodendron and Vouacapoua.

    Most closely related to Pterolobium and Caesalpinia sens. strict. and perhaps best treated as a subgenus of Caesalpinia (Vidal & Hul Thol, 1976b; Herendeen & Zarucchi, 1990; Herendeen & Dilcher, 1991). Other workers have recognised Mezoneuron as a distinct genus (Brenan, 1967; Verdcourt, 1979; Lock, 1989). Mezoneuron is absent from the American tropics and subtropics today, but fossil records show that the taxon was widespread across North America during the Tertiary (Herendeen & Dilcher, 1991) and Caesalpinia sens. strict. has several extant species in the Caribbean. Mezoneuron angolense Welw. ex Oliv. (as Caesalpinia angolensis (Oliv.) Herend. & Zarucchi) is sister to Pterolobium stellatum (Forssk.) Brenan in the combined analysis of Herendeen et al. (2003a)
    Habit
    Prickly climbers, scandent shrubs and small trees
    Ecology
    Tropical and subtropical riverine forest, lowland rain forest, swamp forest, seasonally dry forest, thicket, vine forest and wooded grassland, especially along forest and river margins
    Distribution
    mainly in Asia, extending to Australia, Polynesia, and thinly to Madagascar and Africa; 2 in Africa (1 widespread in W Africa, the other from W to E and SE); 1 endemic in Madagascar, 4 endemic in New Caledonia, 1 endemic in Hawaii, possibly 2 restricted to China, 1 to Vietnam, 4 endemic to Australia (Queensland and NSW), 1 endemic in the Philippines, 1 in Australia and Papua New Guinea, 9 more widespread throughout Asia
    [FTEA]

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

    Habit
    Climbing shrubs, usually armed with prickles on stem and leaves, rarely (not in East Africa) unarmed
    Leaves
    Leaves bipinnate; stipules very small, soon falling; specialized glands restricted to petiole and rhachis absent; leaflets opposite or (but not in East Africa) alternate
    Inflorescences
    Inflorescences of terminal and axillary, often paniculately aggregated racemes; bracts small or very small
    Flowers
    Flowers hermaphrodite
    Calyx
    Sepals 5, imbricate, zygomorphic, the lower one cucullately embracing the others; all arising from a zygomorphic hypanthium
    Corolla
    Petals 5, subequal or the upper one somewhat modified
    Stamens
    Stamens 10, all fertile; filaments alternately longer and shorter, all pubescent or villous below, or (but not in East Africa) glabrous; anthers dorsifixed, dehiscing by longitudinal slits
    Pistil
    Ovary free, sessile or shortly stipitate; style gradually enlarged near apex; stigma small, oblique, not peltate, ciliolate or glabrous
    Fruits
    Pods flat, indehiscent, subcoriaceous, venose, longitudinally and ± broadly winged along the upper suture (wing 3–18 mm. wide)
    Seeds
    Seeds 1–9 per pod, ± transverse, compressed, without endosperm; funicle slender.
    [FZ]

    Leguminosae, R.K. Brummitt, A.C. Chikuni, J.M. Lock & R.M. Polhill. Flora Zambesiaca 3:2. 2007

    Habit
    Climbing shrubs, usually armed with prickles on stem and leaves but rarely (not in the Flora area) unarmed.
    Leaves
    Leaves bipinnate; petiole and rachis without specialised glands; leaflets opposite or alternate (not in the Flora area); stipules very small, caducous.
    Flowers
    Flowers hermaphrodite, with a usually conspicuous hypanthium. Flowers in terminal and axillary racemes or panicles; bracts inconspicuous.
    Calyx
    Sepals 5, imbricate, the lower curving upwards over the others.
    Corolla
    Petals 5, subequal or the upper one somewhat modified.
    Stamens
    Stamens 10, fertile, alternately long and short; filaments pubescent or villous in the lower part or glabrous (not in the Flora area).
    Pistil
    Ovary sessile or shortly stipitate; stigma small, oblique, ciliolate or glabrous.
    Fruits
    Pods oblong-ellipsoid, thickened along the upper margin, or flat with a broad longitudinal wing along the upper margin, chartaceous to coriaceous, indehiscent, 1–9-seeded.
    Seeds
    Seeds compressed, without endosperm.
    [LOWO]
    Use
    Used for medicine and the wood of M. kauaiense (Mann) Hillebr. (uhiuhi) from Hawaii was once used locally for spears and in house construction

    Images

    Distribution

    Native to:

    Andaman Is., Angola, Assam, Bangladesh, Benin, Bismarck Archipelago, Borneo, Burkina, Burundi, Cambodia, Cameroon, Cape Verde, China South-Central, China Southeast, Congo, East Himalaya, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Hawaii, India, Ivory Coast, Jawa, Kenya, Laos, Lesser Sunda Is., Liberia, Madagascar, Malaya, Mozambique, Myanmar, Nepal, New Caledonia, New Guinea, New South Wales, Nicobar Is., Niger, Nigeria, Philippines, Queensland, Rwanda, Senegal, Sierra Leone, Solomon Is., Sri Lanka, Sulawesi, Sumatera, Tanzania, Thailand, Togo, Uganda, Vietnam, Zambia, Zaïre

    Introduced into:

    Pakistan

    Mezoneuron Desf. appears in other Kew resources:

    First published in Mém. Mus. Hist. Nat. 4: 245 (1818)

    Accepted by

    • Clark, R.P. (2016). A taxonomic revision of Mezoneuron (Leguminosae: Caesalpinioideae: Caesalpinieae) Phytotaxa 274: 1-72.
    • Clark, R.P. & Gagnon, E. (2015). A revision of Mezoneuron (Leguminosae: Caesalpinioideae) in New Caledonia, with perspectives on vegetation, geology, and conservation Phytotaxa 207(1):: 68-92.

    Literature

    Flora of West Tropical Africa
    • —F.T.A. 2: 260.
    Flora Zambesiaca
    • in Mém. Mus. Hist. Nat. 4: 245, fig.10, 11 (1818) as Mezonevron.
    Flora of Tropical East Africa
    • in Mém. Mus. Paris 4: 245, t. 10, 11 (1818) (as “ Mezonevron ”)

    Sources

    Flora Zambesiaca
    Flora Zambesiaca
    http://creativecommons.org/licenses/by-nc-sa/3.0

    Flora of Tropical East Africa
    Flora of Tropical East Africa
    http://creativecommons.org/licenses/by-nc-sa/3.0

    Kew Backbone Distributions
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Legumes of the World Online
    http://creativecommons.org/licenses/by-nc-sa/3.0