Newtonia

Taxonomy

Newtonia H.E. Baillon Bull. Mens. Soc. Linn. Paris 1: 721. 1888.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.07.
Tribe: Mimoseae.
Group: Newtonia.
Species Studied - Species in Genus: 6 studied; 11 in genus.

Description

Fruit: A legume; unilocular; 8–60 cm long; 1.3–3.5 cm wide; 0.2–0.3 cm thick; 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight to curved; not plicate; twisted; asymmetrical to symmetrical (slightly); broadly linear, or falcate; with both sutures parallelly curved; not inflated; flattened to compressed; without beak; short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base; right angled with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe up to 10 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along 1 suture (along ventral suture and remaining united along dorsal suture); medial and up and down; passive. Replum invisible. Epicarp dull to glossy; monochrome; light to dark or reddish brown, or black; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; parallel faveolate (arising along dorsal suture and bending or branching longitudinally near center of each valve); not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull to glossy; opaque; monochrome; tan; smooth; without adhering pieces of testa; nonseptate; not exfoliating; entire. Seed(s) 3–8; length parallel with fruit length; overlapping; in 1 series. Funiculus up to 40 mm long; of 1 length only; filiform; curved. Aril absent.

Seed: 28–100 mm long; 9–23 mm wide; 1 mm thick; not overgrown; not angular; symmetrical; oblong (to narrowly so); flattened; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull to glossy; not modified by a bloom; colored; bichrome (lighter colored on wing and darker colored over embryo); tan to brown (reddish, on wing and dark brown to blackish over embryo); glabrous; not smooth; with elevated features; rugose; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) present; continuous around seed (2–20 mm wide (20 mm wide at base)). Raphe not visible. Hilum present; fully concealed; concealed by wing; without faboid split; punctiform (, occluded by wing); marginal according to radicle tip to subapical to radicle tip; flush; not within corona, halo, or rim. Lens not discernible. Endosperm absent. Cotyledons smooth; both outer faces flat; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; notched at radicle; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; straight with embryonic axis; centered between cotyledons. Plumule moderately developed; glabrous.

Distribution

Generic Notes

Newtonia is an African genus according to Lewis and Elias (1981), but they did not place the New World species. The five to seven American species of Newtonia section Neonewtonia A.E. Burkart were treated by Gunn (1984) under phylogenetic number 3.23. Lewis and Lima (1991) examined the Old World and New World species of Newtonia and Pseudopiptadenia (2.3.24). They concluded that the Old World Newtonia species were generically distinct from the New World species and that the New World Newtonia species should be placed in Pseudopiptadenia. They listed the true, African species of Newtonia, and their species count is used. Newtonia aubrevillei, an African species, has a spongy layer below the testa that turns softening solutions red.