Solanum madagascariense
Citation:
Prodr. [A.P. de Candolle] 13(1): 99. 1852.
Type:
MADGASCAR. “In Madagascar”, Collector Unknown (holotype: G-DC [G00144951]).
Last edited by:
Sandra Knapp
Written by:
Sandra Knapp and Maria Vorontsova
Habit:
Liana or small tree (Gentry 11852) to 8 m. Stems terete, flattened or faintly ridged, glabrous to sparsely puberulent with simple unicellular papillae ca. 0.05 mm long, or variously pubescent with a mixture of uniseriate dendritic or arachnoid trichomes to 0.5 mm long, glabrescent or the pubescence less dense with age; new growth glabrous or pubescent with dendritic or arachnoid trichomes like those of the stems; bark of older stems smooth or longitudinally ridged, reddish brown, brown, or yellowish brown, somewhat corky on stems > 1 cm in diameter.
Sympodial structure:
Sympodial units plurifoliate, the leaves not geminate, evenly distributed along young branches.
Leaves:
Leaves simple, (1.5) 3-9 (12) cm long, (1.2) 2-3 (4.5) cm wide, obovate to oblong, thick-chartaceous to thin-coriaceous, often shiny, concolorous to somewhat discolorous, glabrous, sometimes with dendritic trichomes on the midvein on both sides of the lamina; major veins 5-12 pairs, spreading at 60-90° to the midvein and forming loops, the finer venation usually faint or not visible; base cuneate to truncate, sometimes attenuate; margins entire, rarely lobed with a single lobe basally on each side, the lobes up to 8 mm long, rounded, with shallow sinuses; apex acute to acuminate, rarely obtuse and apiculate; petiole 0.4-2 cm long, canaliculate, usually glabrous, less often finely dendritic-pubescent, flexuous and sometimes twining around supports (e.g., Humbert 31597, Miller & Randrianasolo 4339).
Inflorescences:
Inflorescences terminal at the apex of branches, (2.5)5-20(25) cm long, furcate or several times branched, with (8)15-45(100) flowers, glabrous or with variable dendritic pubescence paralleling that of the stems; peduncle 1.5-5 cm long; pedicels 0.4-1.1 cm long, apically dilated, always glabrous, when the rachis is pubescent a clear boundary line visible between the glabrous petiole and the pubescent rachis (a few trichomes occasionally found at the pedicel base) , articulated 0-2 mm from base; pedicel scars irregularly spaced 1-4 mm apart, often appearing as apically dilated pegs. Buds globose or broadly ellipsoid, the corolla soon exserted from the calyx tube.
Flowers:
Flowers 5-merous, apparently all perfect. Calyx tube 2-3 mm long, broadly cup-shaped or conical, the lobes up to 1 mm long, 1.5-2 mm wide at base, often irregular or almost absent, broadly deltate, rounded to cuspidate at the tips, glabrous or with sparse short simple trichomes; margin often thickened, with dense tufts of simple hairs at the tips. Corolla 1-2 cm in diameter, white to violet, stellate, lobed almost to base, the lobes 4-10 mm long 1.5-2.5 mm wide, narrowly deltate to linear, sometimes aristate with a puberulous appendage ca. 0.5 mm long arising from the adaxial surface of the lobe just below the apex, glabrous adaxially, glabrous to puberulous abaxially with dendritic trichomes that are longer at the lobe tips. Stamens equal; filament tube 0.5-1 mm; free portion of the filaments 1-2 mm; anthers 2.5-4 mm long, ca. 1.5 mm wide, broadly ellipsoid, usually somewhat connivent, smooth or papillose abaxially, poricidal at the tips, the pores about the same diameter as the anther apices, clearly delineated and not lengthening with age. Ovary conical, glabrous; style 6-12 mm long, protruding 1.5-4 mm beyond the anthers, straight or curved, glabrous; stigma clavate to capitate, the surface smooth to minutely papillose.
Fruits:
Fruit a globose berry, sometimes ellipsoid, 0.5-1.2 cm diameter, black or purplish black at maturity, the pericarp thin, collapsing on drying to reveal the outline of the seeds, glabrous; fruiting pedicels 1-1.2 cm long, 0.5-0.7 mm diameter at base, pendent to spreading; fruiting calyx slightly accrescent, the lobes becoming woody with a light-coloured margin.
Seeds:
Seeds 20-40(+) per berry, 1.5-4 mm long, 1-2.5 mm wide, ovoid reniform or somewhat flattened, golden-orange or reddish brown, the surface deeply pitted, the testal cells pentagonal or slightly sinuate in outline.
Chromosome number:
Not known.
Distribution:
Solanum madagascariense is endemic to Madagascar, throughout central and eastern parts of the island, with a few records from humid forests on the western part of the island. It grows in a wide variety of humid and subhumid forests; sometimes found in disturbed vegetation by the roadside; 0-1500 m elevation.
Common names and uses:
Madagascar. Antsiranana: vahimasina (Humbert 18109), vahimbingy (RN Madagascar 2738, Miller & Randrianasolo 4563), vahinazo (RN Madagascar 8388), voajaboala (Miller & Randrianasolo 4329); Fianarantsoa: keranzy (Anon. 4026), vahimaitso (Malcomer et al. 1581), vahivahy (Randriantafika 15). No uses recorded.
Conservation status:
Preliminary conservation status (IUCN 2014). Least Concern (LC). EOO 551,384 km2 (LC), AOO 436 km2 (EN). Solanum madagascariense is a common liana, and occurs in several different forest types, including in some protected areas. Its local rarity and patchiness of distribtition, along with its range of morphological varability (see below) suggest further studies as to local abundance are necessary.
Solanum madagascariense is a liana with prominent terminal inflorescences of 15-45 white to deep purple flowers (Fig. 1C in Knapp and Vortonsova 2016), sturdy branches, and thick leaves. It occurs throughout Madagascar’s wet forests which are situated predominantly on the eastern coast, adjacent parts of the High Plateau, and northern parts of the island. It is the most common and variable species of endemic non-spiny Solanum.
Solanum madagascariense is similar and possibly closely related to the rare and local species S. trichopetiolatum and S. humblotii. It can be distinguished from S. trichopetiolatum by its glabrous petioles (versus petioles with long simple trichomes 0.5-0.15 mm long); S. trichopetiolatum also has looser inflorescences with finer branches and fewer flowers, a greater tendency towards discolorous oblong leaves and is restricted to a narrow area of Antsiranana. Solanum madagascariense differs from S. humblotii in its large, many-branched inflorescence with many flowers; S. humblotii has an unbranched inflorescence with few flowers and is restricted to the northern part of Madagascar in Toamasina.
Solanum madagascariense as delimited here encompasses great range of variation. It is possible to isolate groups of specimens with small long narrow leaves, groups of specimens with wide coriaceous leaves and fewer veins, and groups of specimens with sparse inflorescences and hariy leaves, but intermedidates between all these forms are common. The name S. apocynifolium has been used to describe individuals with tomentose stems and smaller leaves. Variation in indumentum is continuous with that observed in other populations of S. madagascariense, and leaf size seems to be largely determined by ecological factors. Solanum apocynifolium was accepted by Bitter (1917), tentatively accepted by D’Arcy and Rakotozafy (1994) with acknowledgement of continuous variation, and accepted at the level of variety by the late R.N. Lester (unpublished manuscript). Forms recognised as the two taxa are the extremes of a range of morphological variation and are here considered to be conspecific. Solanum nitens is a smaller glabrous variant of S. madagascariense with shiny subcoriaceous leaves and a shrubby, densely branched growth form that grows in drier, more central areas of Madagascar. It was accepted by Bitter (1917), reduced to a variety by D’Arcy and Rakotozafy (1994) and considered a synonym of S. madagascariense by Lester (unpublished manuscript). We agree with Richard Lester’s assessment and S. nitens is included in S. madagascariense as an arid environment variant. Solanum antalaha is a wet environment variant of S. madagascariense occurring further north, representing mature or shade dwelling individuals. Solanum antalaha has glabrous leaves, petioles, stems, and corolla, and leaves with fewer veins; it was described as having larger anthers but these are less than 3.8 mm long on the type specimen, within the variation range of S. madagascariense (2.5-4 mm long). Solanum marojejy was described as a Marojejy endemic with dorsally papillose anther surfaces and glabrous petioles; both of these features, however, are commonly observed in populations of S. madagascariense from other localities. Solanum marojejy is here considered to be conspecific with S. madagascariense. Solanum clerodendroides is a specimen of S. madagascariense almost certainly incorrectly labelled as collected in Nigeria (fide H. Heine 1967, in sched.)
Unusually large papillae seen on the abaxial anther surface of some collections have been postulated to restrict access to pollen or provide support or orientation cues for pollinating bees (D’Arcy 1992). Only three specimens with lobed leaves have been seen, but lobed leaves may be more common in juvenile plants as is true in the Dulcamaroid clade (Knapp 2103). An unusual specimen at P from a cultivated plant in the garden at Antananarivo (s. coll. 2174, P04063654) is from a plant with inflorescences on many short branches and only 2-3 flowers per inflorescence and somewhat resembles S. humblotii, but morphologically conforms to S. madagascariense in terms of floral form, calyx size and leaf morphology.
We have chosen Forsyth-Major 15 [K000414184] as the lectotype for S. madagascariense Dammer (nom. illeg., a later homonym of S. madagascariense Dunal) as it is the only unambiguous duplicate of the type collection number we have found. It is probable that the sheet at BM labelled Forsyth-Major 55 [BM000887181] is another duplicate (and thus an isolectotype), curatorial annotation on the BM sheet suggests 55 may be an error for 15.
The protologue of S. antalaha cites a holotype at P; of the two duplicates of the type collection P00349362 has been selected as the lectotype because it annotated as “holotype” in W.G. D’Arcy’s handwriting.