Newtonia Baill., Bull. Mens. Soc. Linn. Paris 1(91): 721. 1888.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/4E7E31CD-AA0A-1386-17C2-66918192843B |
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scientific name |
Newtonia Baill., Bull. Mens. Soc. Linn. Paris 1(91): 721. 1888. |
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Newtonia Baill., Bull. Mens. Soc. Linn. Paris 1(91): 721. 1888. View in CoL
Figs 127 View Figure 127 , 131 View Figure 131
Type.
Newtonia insignis Baill. [= N. duparquetiana (Baill.) Keay]
Description.
Unarmed large trees, often with buttresses (Fig. 127D View Figure 127 ) and aerial roots (one species a liana), tuberous storage roots absent; brachyblasts absent. Stipules small, caducous. Leaves bipinnate, extrafloral nectaries present between the proximal pair of pinnae and usually between all pairs, sessile or stipitate, crateriform to cylindrical; pinnae 1-27 pairs, opposite; leaflets 1-40 (67) pairs per pinna, opposite, sessile, pinnately veined, brochidodromous. Inflorescences paniculiform comprising aggregated spikes (Fig. 127H View Figure 127 ) (a raceme in one species), terminal or subterminal. Flowers sessile or pedicellate, functionally staminate or bisexual; hypanthium absent but the stamens and petals fused into a stemonozone, forming a nectary disk in several species; calyx 5 lobed, valvate; petals 5, valvate, basally connate or adnate to stamens; stamens 10, free above the stemonozone, anthers dorsifixed, anther glands present or absent; pollen in tricolporate monads, exine smooth (perforated), columellae present; ovary stipitate, stigma porate. Fruits strongly dorsiventrally flattened, dehiscing along ventral suture (Fig. 127N View Figure 127 ), valves coriaceous, exocarp brown, reticulately veined, endocarp lighter in colour, mesocarp absent. Seeds strongly flattened, winged (Fig. 127N View Figure 127 ), longitudinal, the testa thin, pleurogram absent, funicle attached apically.
Chromosome number.
2 n = 26 ( Goldblatt 1981b).
Included species and geographic distribution.
Eleven species, restricted to, but widely distributed in tropical Africa (Fig. 131 View Figure 131 ).
Ecology.
Newtonia species are (with the exception of N. scandens Villiers) large trees, often with buttresses (Fig. 127D View Figure 127 ) and aerial roots, mostly in rainforests, although some species are found in more seasonal semi-deciduous forest in East Africa (Fig. 131 View Figure 131 ). Seeds wind-dispersed (Fig. 127N View Figure 127 ).
Etymology.
Named by Baillon in honour of the English philosopher and mathematician Isaac Newton.
Human uses.
Various species are used for timber ( Fern 2023).
Notes.
Newtonia is one of three genera of large, unarmed African trees with winged seeds that form part of the grade subtending the core mimosoid clade (Fig. 126 View Figure 126 ). The follicular dehiscence of fruits of Newtonia , i.e., along one margin only, to release the winged, wind-dispersed seeds (Fig. 127N View Figure 127 ), is unusual in Mimoseae and found in only a few other genera (e.g., Cylicodiscus , Piptadeniastrum Brenan, Pityrocarpa (Benth.) Britton & Rose, and Marlimorimia L.P. Queiroz, L.M. Borges, Marc.F. Simon & P.G. Ribeiro). The spicate inflorescences are always aggregated into compound paniculiform terminal inflorescences (Fig. 127H View Figure 127 ).
In the past, several New World species were included in Newtonia . These are now placed in the genus Marlimorimia , a genus of the Stryphnodendron clade segregated from Pseudopiptadenia Rauschert by Borges et al. (2022), reflecting long-documented differences in pollen type [tricolporate monads in Newtonia vs polyads in Pseudopiptadenia (now Marlimorimia ; Guinet 1969)] and other morphological differences ( Lewis and Elias 1981; Lewis and Lima 1991).
Taxonomic references.
Brenan (1959); Hutchinson and Dalziel (1958); Mackinder and Cheek (2003); Villiers (1989, 1990), all 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.