Mezoneuron Desf., Mem . Mus. Hist. Nat. 4: 245. 1818.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/BEBC2325-DF20-57AC-9417-7C52EEB141AA |
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scientific name |
Mezoneuron Desf., Mem . Mus. Hist. Nat. 4: 245. 1818. |
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Mezoneuron Desf., Mem. Mus. Hist. Nat. 4: 245. 1818. View in CoL
Figs 37 View Figure 37 , 64 View Figure 64
Mezonevron Desf., Mém. Mus. Hist. Nat. 4: 245. 1818, orth. var.
Mezoneurum DC., Prodr. [A.P. de Candolle] 2: 484. 1825, orth. var.
Caesalpinia subg. Mezoneuron (Desf.) Vidal ex Herend. & Zarucchi, Ann. Missouri Bot. Gard. 77(4): 854. 1990.
Type.
Mezoneuron glabrum Desf. [= Mezoneuron pubescens Desf.]
Description.
Scrambling shrubs or lianas, occasionally medium-sized trees, usually armed with recurved prickles on stem and leaves, rarely unarmed. Stipules triangular, often caducous. Leaves bipinnate, ending in a pair of pinnae; pinnae in (1) 2-18 opposite to sub-opposite pairs; leaflets in 1-15 opposite to alternate pairs per pinna. Inflorescence a terminal or axillary raceme (often aggregated into panicles). Flowers bisexual, zygomorphic; hypanthium persisting as a small cup or wide shallow cup as the fruit matures; sepals 5, imbricate, the lower sepal cucullate, and overlapping the other 4 in bud, caducous; petals 5, free, usually yellow with red markings on the median petal, or occasionally red, pink or cream, the median petal somewhat modified (either with a fleshy ligule or a patch of hairs on the inner surface between the blade and claw, or the petal bilobed); stamens 10, free, usually all pubescent or villose on lower half, or one or all glabrous; ovary glabrous to hairy. Fruit laterally compressed, indehiscent, chartaceous, coriaceous or woody, venose, longitudinally (and often broadly) winged along the upper suture, the wing 2-20 mm wide, 1-13-seeded. Seeds ± transversely arranged in seed chamber, compressed.
Chromosome number.
2 n = 22 ( M. cucullatum , M. kauaiense ) ( Rice et al. 2015).
Included species and geographic distribution.
Twenty-four species, mainly in Asia, extending to Australia, Polynesia (including Hawaii), New Caledonia, Madagascar and Africa (Fig. 64 View Figure 64 ).
Ecology.
Tropical and subtropical riverine forests, lowland rainforests, swamp forests, seasonally dry forests, thickets, vine forests and wooded grasslands, especially along forest and river margins.
Etymology.
From Greek, meso - (= middle) or meizon (= greater) and neuron (= nerve), the upper suture of the fruit is bordered by a usually broad longitudinal wing so that the suture appears as a prominent sub-central nerve or vein.
Human uses.
Used for medicine; the wood of M. kauaiense (Mann.) Hillebr. ( “uhiuhi”) from Hawaii was once used locally for spears and in house construction ( Lewis 2005b).
Notes.
Mezoneuron is absent from the American tropics and subtropics today, but fossil records show that the genus was widespread across North America, as well as in Europe, during the middle Eocene, about 45 Ma ( Herendeen and Dilcher 1991). A revision of Mezoneuron by Clark (2016) provides full synonymy, a key to species, and a list of fossil taxa associated with this genus.
Taxonomic references.
Brenan (1967); Brummitt et al. (2007); Clark (2016); Clark and Gagnon (2015); Du Puy and Rabevohitra (2002); Gagnon et al. (2016); George (1998); Hattink (1974); Herendeen and Zarucchi (1990); Lock (1989); Pedley (1997); Verdcourt (1979); Vidal and Hul Thol (1976); Wagner et al. (1999).
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