Solanum torvoideum Merr. & L.M.Perry, J. Arnold Arb. 30: 47. 1949.

Aubriot, Xavier & Knapp, Sandra, 2022, A revision of the " spiny solanums " of Tropical Asia (Solanum, the Leptostemonum Clade, Solanaceae), PhytoKeys 198, pp. 1-270 : 1

43. Solanum torvoideum Merr. & L.M.Perry, J. Arnold Arb. 30: 47. 1949.

Fig. 71

Type.

Papua New Guinea. Central: Mafulu, Sep-Nov 1933, L.J. Brass 5411 (lectotype designated by Symon 1985, pg. 150, as “holotype”: A [00077838]; isolectotypes: BM [BM000886267], BRI [BRI-AQ0080383], L [L.0003661], NY [00172294]) .

Description.

Shrubs to small trees, 1-5 m tall, unarmed or rarely sparsely armed. Stems erect, terete, usually unarmed or with a few broad-based straight prickles, stellate-pubescent; prickles, if present, 2-3 mm long, to 1.5 mm wide at the base, very sparse, straight, pale yellowish tan; pubescence of sessile to very short-stalked porrect-stellate trichomes, the stalks to 1 mm long, the rays 6-8, ca. 0.5 mm long, the midpoints absent or to 1 mm long (New Guinea only); new growth densely stellate-pubescent, the trichomes tangled, somewhat golden in dry material; bark of older stems grey to dark brown, glabrescent. Sympodial units difoliate, the leaves geminate, the leaves of pair equal in size and shape or one leaf slightly smaller. Leaves simple, shallowly lobed, the blades (7-)12-25 cm long, (2-)3-11 cm wide, 2.5-4 times longer than wide, elliptic to narrowly elliptic, chartaceous, discolorous, unarmed or sparsely armed along the midrib and major veins with small straight prickles; adaxial surface dark green, evenly and moderately to densely pubescent with golden short-stalked porrect-stellate trichomes, the stalks to 0.5 mm long, the rays 4-6, ca. 0.5 mm long, the midpoints absent or to 0.5 mm (in some New Guinea populations the midpoints glandular); abaxial surface with similar short-stalked porrect-stellate trichomes, but with more numerous rays (up to 10-12); major veins 4-7 pairs, densely pubescent especially abaxially; base acute, somewhat oblique; margins shallowly lobed, the lobes 4-7, 0.5-3 cm long, deltate to triangular, apically acute, the sinuses ca. one third of the way to the midrib; apex acute; petioles 1.5-3(-4+) cm long, ca. 1/4 as long as the leaf blades, sparsely prickly and densely to moderately pubescent with short-stalked stellate-trichomes like those of the stems, unarmed or prickly with 1-3 prickles like those of the stems. Inflorescences 4-9 cm long, internodal and lateral, forked to several times branched, with 50-70+ flowers, several flowers open at any one time, densely pubescent with short-stalked stellate-porrect trichomes like those of the stems, with 6-8 rays ca. 0.5 mm long and midpoints to 1 mm long, unarmed; peduncle absent and the first inflorescence branches appearing to arise directly from the stem, or 0.5 cm long, unarmed; pedicels 1-1.2 cm long, ca. 1 mm in diameter at the base and apex, spreading to erect at anthesis, densely stellate-pubescent like the inflorescence axes, articulated at the base, unarmed; pedicel scars irregularly spaced 1-2 mm apart. Buds elongate ellipsoid and somewhat tapering, strongly exserted from the calyx before anthesis. Flowers 5-merous, apparently all perfect, but some distal flowers may be short-styled. Calyx with the tube 2-3 mm long, conical, the lobes 2-5 mm long, 1-2 mm wide, deltate with a subulate acumen 1.5-2 mm long, densely stellate-pubescent with porrect-stellate trichomes like those of the pedicels, the acumen sometimes more glabrous and drying dark. Corolla 2-2.6 cm in diameter, white, shallowly stellate, lobed ca. halfway to the base, interpetalar tissue present and abundant, the lobes 8-10 mm long, 4-7 mm wide, spreading at anthesis, mostly glabrous adaxially but with a few stellate trichomes at the tips, densely stellate-pubescent abaxially with densely tangled sessile trichomes where exposed in bud, these densest at the tips, the interpetalar tissue glabrous. Stamens equal; anthers 5-6.5 mm long, ca. 1 mm wide, connivent or somewhat spreading, tapering, yellow, glabrous, poricidal at the tips, the pores directed distally, not elongating to slits with drying; filament tube minute, glabrous; free portion of the filaments 0.5-1 mm long, glabrous. Ovary conical, glabrous; style 6-9 mm long, glabrous; stigma capitate, the surfaces minutely papillose. Fruit a globose berry, several to many per infructescence, 1-1.4 cm in diameter, the pericarp thin and shiny, yellow to orange-yellow when ripe, aging to brown or almost black (fide Symon 1985), glabrous; fruiting pedicels 1.5-2 cm long, ca. 1.5 mm in diameter at the base, 3-3.5 mm in diameter at the apex, woody, erect or somewhat spreading from weight of berries; fruiting calyx not accrescent, the lobes often breaking off. Seeds 60-100 per berry, 2-3.5 mm long, ca. 2 mm wide, flattened reniform, pale tan or yellowish brown, the surfaces minutely pitted, the testal cells with sinuate margins. Chromosome number: n = 12 ( Symon 1985; voucher Symon 10669 from Papua New Guinea).

Distribution

(Fig. 72 ). Solanum torvoideum occurs from the Sunda Islands in Indonesia and Timor Leste east to the Philippines and the island of New Guinea.

Ecology and habitat.

Solanum torvoideum is a species of disturbed areas such as old garden sites, treefalls or roadsides; from 300 to 2,000 m elevation (higher elevations from New Guinea specimens). Symon (1985) records it as occurring in fagaceous forest and on gravelly stream beds on New Guinea.

Common names and uses.

Philippines. Mindanao: bokul [Bukid] (Sulit 9868), tangutaungan (Zwickey 52), gebubruca (Frake 38012); Luzon: tanutong (Maliwanang 229).

Preliminary conservation status

( IUCN 2019). Least Concern (LC). EOO (2,372,285 km2, LC); AOO (212 km2, EN). As a specialist of disturbed areas with a wide distribution when the island of New Guinea is taken into account, S. torvoideum is not of conservation concern.

Discussion.

Solanum torvoideum is a member of the Torva clade (see Aubriot et al. 2016a) and like others in the group has difoliate sympodia with usually geminate leaves, highly branched inflorescences, straight or only slightly curved stem prickles, and sticky leathery berries. The Asian species of “torvoids” differ from their American relatives in having red, rather than green berries at maturity. In the area treated here S. torvoideum is most similar to the introduced and widespread S. torvum , from which it differs in its denser, more reddish gold pubescence, eglandular inflorescences, and red berries. In general, plants of S. torvoideum are more robust-looking than those of S. torvum . Solanum torvoideum is superficially similar to another introduced species, S. Solanum chrysotrichum in its pubescence, but is not sympatric with it, and can be distinguished by fruit colour. It can be distinguished from S. poka and S. pseudosaponaceum in its more branched inflorescences with denser pubescence and larger flowers (to 2.6 cm in diameter versus to 2 cm or 1.5 cm in diameter).

On the island of New Guinea, S. torvoideum is most similar to the sympatric S. dammerianum Lauterb. & Schum. ( Symon 1985). Solanum torvoideum differs from S. dammerianum in is rusty (versus drab) leaf pubescence, its more compact and fewer branched inflorescence and its larger mature berries (to 2 cm in diameter versus to 1.5 cm in diameter). The type of S. dammerianum has been lost ( Symon 1985) so further intensive study of New Guinea populations may reveal additional differences.

The Torva clade species occurring in tropical Asia are all each other’s closest relatives, suggesting a single dispersal event from the Americas ( Aubriot et al. 2016a).

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 71. Solanum torvoideum Merr. & L. M. Perry A herbarium specimen collected in the Philippines in 1954 (Frake 20323, L. 2771110) B habit (field photograph, unvouchered, Philippines) C detail of the inflorescence (field photograph, unvouchered, Philippines). Photograph credits: A Naturalis Biodiversity Center B, C P. B. Pelser.

Figure 72. Distribution of S. torvoideum.