Solanum poka Dunal, Encycl. [J. Lamarck & al.] Suppl. 3: 768. 1814.

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

31. Solanum poka Dunal, Encycl. [J. Lamarck & al.] Suppl. 3: 768. 1814.

Fig. 51

Solanum torvum Sw. var. scabrescens Miq., Fl. Ned. Ind. 2: 648. 1857. Type. Indonesia. Sumatra: Sin. loc., F.W. Junghuhn s.n. (lectotype, designated here: L [L.0403917]; isolectotype: U [U0113979]).

Solanum torvum Sw. var. polyacanthum Miq., Fl. Ned. Ind. 2: 648. 1857, as " polyacantha ". Type. Indonesia. Java: sin. loc., T. Horsfield s.n. (lectotype, designated here: BM [BM000886307]).

Type.

Based on an unpublished illustration of a Jean-Baptiste Leschenault de la Tour collection from Java kept in the Node-Véran collection in Montpellier (lectotype, designated by Aubriot et al. 2016b, pg. 105: [illustration] Sol. Tab. 55 [MPU028527]).

Description.

Shrubs to 3 m, armed. Stems erect, terete, usually densely prickly distally, moderately pubescent, glabrescent; prickles to 3.5 mm long, to 2.5 mm wide at the base, straight, awl-shaped to deltate, conical, pale yellow, glabrescent; pubescence of mixed sessile and variously stalked porrect-stellate trichomes, the stalks to 0.2 mm long, the rays (4-)5-8, 0.1-0.25 mm long, the midpoints reduced to mere bumps; new growth moderately stellate-pubescent, black to dark brownish in dry material; bark of older stems brownish grey, sparsely stellate-pubescent. Sympodial units difoliate, the leaves geminate. Leaves simple, entire to deeply lobed, the blades 11-24 cm long, 4-13 cm wide, ca. 1.5-3 times longer than wide, elliptic to broadly ovate, chartaceous, slightly discolorous, unarmed or pricky with 1-6 prickles per leaf side, the prickles to 6 mm long, to 1.5 mm wide at the base, straight or slightly curved at the tip, awl-shaped, conical, pale yellow, glabrous; adaxial surface moderately stellate-pubescent with porrect, sessile and less often variously stalked trichomes, the stalks to 0.1 mm long, the rays 4-8, 0.1-0.4 mm long, the midpoints to 0.25 mm long; abaxial surface moderately stellate-pubescent with trichomes like those of the adaxial surface, but more often stalked; major veins 6-8 pairs drying yellow; base short-attenuate to truncate; margins entire or shallowly to deeply lobed, the lobes 1-5 on each side, 0.5-5 cm long, deltate, rounded to apically acute, the sinuses extending up to 2/3 of the distance to the midvein; apex acute; petiole 1.5-4 cm long, 1/10-1/5 of the leaf blade length, densely stellate-pubescent with porrect, sessile trichomes like those of the blades, unarmed or prickly with 1-5 prickles like those of the stems. Inflorescences 2-5 cm long, apparently lateral or leaf opposed, unbranched to up to 2 times branched, with ca. 5-20 flowers, 2-6 flowers open at any one time, moderately to densely stellate-pubescent with porrect-stellate trichomes like those of the stems, unarmed; peduncle 0.5-1.5 cm long, unarmed or with very few prickles; pedicels 0.5-1.2 cm long, ca. 1 mm in diameter at the base, ca. 1.5 mm in diameter at the apex, erect, unarmed, densely stellate-pubescent with porrect-stellate trichomes like those of the inflorescence axes, articulated at the base; pedicel scars spaced 2-4 mm apart. Flowers 5-merous, apparently all perfect. Calyx with the tube 1-3 mm long, conical, the lobes 3-5 mm long, ca. 1.5 mm wide, the lower part deltate and abruptly constricting to an elongate acumen, the acumen 3/4 of the total lobe length, the abaxial surface more or less strongly keeled along the midvein, unarmed, densely stellate-pubescent on the midvein with porrect-stellate trichomes like those of the pedicels. Corolla 1-2 cm in diameter, white, stellate, lobed ca. 1/2-2/3 of the way to the base, the lobes 5-8 mm long, 2-3.5 mm wide, deltate, spreading at anthesis, densely stellate-pubescent abaxially on parts exposed in bud. Stamens equal; anthers 5-6.5 mm long, ca. 0.75 mm wide, tapering, yellow, connivent, glabrous, poricidal at the tips, the pores not lengthening to slits with age; filament tube <0.5 mm long, glabrous; free portion of the filaments 0.75-1.5 mm long, glabrous. Ovary conical, minutely glandular-puberulent; style 0.6-1 cm long, slender, curved at the apex, with a few scattered hairs at the tip; stigma capitate, minutely papillate, stellate-pubescent. Fruit a globose berry, 8-18 per infructescence, 0.8-1.5 cm in diameter, the pericarp smooth, bluish green when young, turning to dark greyish yellow, glabrous; fruiting pedicels 1.2-2.5 cm long, ca. 1-1.5 mm in diameter at the base, 2-3 mm in diameter at the apex, woody, erect, unarmed; fruiting calyx lobes not expanding. Seeds 100-200 per berry, 1.75-2 mm long, 1.5-1.75 mm wide, flattened reniform, pale yellowish, the surface minutely pitted, the testal cells sinuate in outline. Chromosome number: not known.

Distribution

(Fig. 52 ). Solanum poka is widely distributed in the Malay Archipelago, from western Sumatra to the Maluku Islands and across Sulawesi, northwards to the Talaud islands.

Ecology and habitat.

Solanum poka is a plant of evergreen broadleaf forests, growing in open woodland, forest edges, degraded vegetation, usually on limestone or volcanic rocks; from sea level to 1,600 m elevation.

Common names and uses.

Indonesia. Java: pooka (Horsfield 786), daun Solanum poka ( Dunal 1814); North Sulawesi: poki poki (De La Savinierre 343bis), sangkirumanuwawi (Lam 2772).

Preliminary conservation status

( IUCN 2019). Least Concern (LC). EOO (1,202,780 km2, LC); AOO (68 km2, EN). Although the EOO measurement indicates a status of least concern, the few collections coupled with the profound transformation in lowland Indonesian habitats where S. poka is found ( Margono et al. 2014) suggest that the species is a priority for recollection and reassessment.

Discussion.

Solanum poka is a member of the Torva clade ( Aubriot et al. 2016a) and is similar to other members of the group occurring in southeast Asia such as S. pseudosaponaceum and S. torvoideum . Morphologically, S. poka most closely resembles S. pseudosaponaceum , a widespread species ranging from Taiwan and southern China to Indonesia but differs in having denser indumentum on the adaxial leaf surface, more numerous straight prickles on the upper stems, fewer, larger flowers with elongate strongly keeled calyx lobes, and much larger fruits. Flowers of S. pseudosaponaceum are lilac or purplish-white while those of S. poka are always described on labels as white. Solanum poka can be distinguished from the introduced S. torvum in its strongly keeled calyx lobes with elongate acumens (rather than deltate lobes), red (rather than green) berries, and in the lack of simple glandular trichomes in the inflorescence.

Aubriot et al. (2016b) recognised S. torvum var. scabrescens as a synonym in their resurrection of the name S. poka but erroneously referred to the Leiden duplicate (L.0403917) of the Junghuhn s.n. collection cited in the protologue as “holotype”; Miquel (1857) cited no herbaria in the protologue. They did not include Miquel’s var. Solanum poka polyacanthum in the synonymy of S. poka , but the minimal description with reference to pricklier stems and leaves approaching S. giganteum , however, suggest this varietal name refers to the taxon we recognise as S. poka . The protologue states no specific locality, merely "β. Java (Horsfield)". We have therefore selected the specimen of S. poka from Java collected by Thomas Horsfield that best matches the protologue at BM (BM000886307) as the lectotype for S. torvum var. polycanthum .

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 51. Solanum poka Dunal - Herbarium specimen (epitype) collected in Indonesia (Horsfield s. n., BM 000886306). Photograph credit: CC-BY, © copyright The Trustees of the Natural History Museum, London.

Figure 52. Distribution of S. poka.