Plathymenia Benth., J. Bot. (Hooker) 4: 333. 1841.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/25B94088-5364-57A5-C41A-A9F8B8DFF9D8 |
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Plathymenia Benth., J. Bot. (Hooker) 4: 333. 1841. |
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Plathymenia Benth., J. Bot. (Hooker) 4: 333. 1841. View in CoL
Figs 127 View Figure 127 , 129 View Figure 129
Pirottantha Speg., Anales Soc. Ci. Argent. 82: 226. 1916 (publ. 1917). Type: Pirottantha modesta Speg. [= Plathymenia reticulata Benth.]
Type.
Plathymenia reticulata Benth.
Description.
Unarmed deciduous trees (Fig. 127B View Figure 127 ), 2.5-12 (40) m; stems dark, terete, glabrous to glaucous, waxy; brachyblasts absent. Stipules rudimentary or caducous. Leaves bipinnate; extrafloral nectary absent or occasionally with an inconspicuous lump on the petiole; pinnae 3-10 pairs, opposite, sub-opposite or distinctly alternate, terminating in an adaxial, crateriform nectary; leaflets 6-20 per pinna, mostly alternate, conspicuously brochidodromous. Inflorescences spiciform racemes in leaf axils or more frequently above the axils (Fig. 127F View Figure 127 ). Flowers pedicellate, pedicels persistent and peg-like after abscission of unfertilised flowers; calyx 5-toothed, campanulate; petals 5, pale green, glabrous or sparsely pubescent on the apex, apparently separate to base; stamens 10, filaments white, free to the base, connective somewhat enlarged, anther glands large, apical, stipitate, round; pollen in tricolporate monads with a smooth (perforated) exine with columellae; ovary stipitate, stigma tubular. Fruits linear-oblong, tardily dehiscent through both sutures, strongly dorsiventrally flattened, the valves coriaceous (Fig. 127J View Figure 127 ), endocarp chartaceous forming membranous rectangular packets around the seeds, separating from the valves at maturity, and dispersed with the seeds enclosed (Fig. 127K View Figure 127 ). Seeds dorsiventrally flattened, the testa hard, pleurogram present, closed.
Chromosome number.
2 n = 26 ( Goldblatt 1981b).
Included species and geographic distribution.
Monospecific ( P. reticulata ), restricted to South America, primarily in central and eastern Brazil but extending to east-central Paraguay, Bolivia, and southern Suriname (Fig. 129 View Figure 129 ).
Ecology.
Mainly in deciduous rocky cerrado (savanna) (Fig. 127B View Figure 127 ) and sparse cerradão woodland, extending weakly into wetter coastal Mata Atlântica forests and seasonally dry tropical forests, mainly 300-1100 m elevation.
Etymology.
From Greek, platy (= flat) and hymen (= membrane), in reference to the membranous endocarp breaking up into papery square envelopes in which the seeds are dispersed (Fig. 127K View Figure 127 ).
Human uses.
The timber of P. reticulata is used for furniture and fence posts. The bark has been used medicinally ( Warwick and Lewis 2003).
Notes.
Plathymenia forms its own monogeneric (and monospecific) lineage embedded in the grade that subtends the core mimosoid clade (Fig. 126 View Figure 126 ). In fruit, Plathymenia is unusual among Mimoseae in its endocarp forming papery packets around the seeds (Fig. 127K View Figure 127 ). Previously two species were recognised in the genus, however Warwick and Lewis (2003) concluded that there is only a single polymorphic species, noting that the various morphological variants do not correlate with geography or ecology.
Taxonomic references.
Bentham (1876); Warwick and Lewis (2003), both with illustrations.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.