Solanum wightii Nees, Trans. Linn. Soc. London 17(1): 51. 1834.

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

50. Solanum wightii Nees, Trans. Linn. Soc. London 17(1): 51. 1834.

Fig. 82

Solanum hohenackeri Van Heurck & Müll.Arg., Observ. Bot. (Van Heurck) 87. 1870. Type. India. Tamil Nadu: Nilgiris, "in montibus Nilagiri", R.F. Hohenacker 1076 (lectotype, designated here: BR [AWH10071212]; isolectotypes: BM [BM000778309], G [G00442609, G00442943, G00442944], HAL [HAL0010834], K [K000441384], L [0403690], LE [2 sheets], MEL [MEL2446521], P [P00055713, P00055714], W [acc. # 0000605]).

Solanum pulneyensis Soosairaj, Adansonia sér. 3, 43(21): 236. 2021. Type. India. Tamil Nadu: Dindigul district, Palani Hills National ark, Thonimalai, ca. 1300 m, 29 Jan 2018. S. Soosairaj 2514 (holotype: RHT [acc. # 076723]; isotype: MH).

Type.

India. Sin. loc., "Peninsula Ind. orientalis", R. Wight 1576/126 (lectotype, designated here: GZU [GZU000255932]; isolectotypes: BM [BM000900156], E [E00179475, E00179476, E00179477], G [G00442945], K [K000441376, K000441378, K000441379], LE [LE00017069]) .

Description.

Scrambling herbs or shrubs to 2 m tall, armed or unarmed. Stems erect or spreading, terete, prickly and stellate-pubescent; prickles, if present, to 3 mm long, 1.5-2 mm wide at the base, slightly curved, pale yellowish tan; pubescence of sessile to very short-stalked porrect-stellate trichomes, the stalks, if present, to 0.2 mm, the rays 4-6, ca. 0.5 mm long, the midpoints 2-4 celled, to 2 mm long, glandular tipped, drying with violet tinge at cell junctions (trichomes described as black to reddish Clarke 10793); new growth densely stellate-pubescent, the trichomes tangled, soon deciduous and the stems glabrate; bark of older stems ashy white. Sympodial units difoliate, the leaves not geminate. Leaves simple, shallowly lobed, the blades 2-9 cm long, 1.7-6.8 cm wide, 1-1.3 times longer than wide, ovate to broadly triangular, widest in the lower third, chartaceous, somewhat discolorous, unarmed or very occasionally sparsely armed along the midrib and major veins with small prickles; adaxial surface evenly and densely pubescent with sessile and very short-stalked porrect-stellate trichomes, the rays 4-8, to 0.5 mm long, glandular at the tips, the midpoints 2-4-celled, to 2 mm long, glandular at the tips; abaxial surface with similar porrect-stellate trichomes, but these denser especially along the veins; major veins 3-4 pairs, densely pubescent; base abruptly truncate to cordate, somewhat oblique; margins shallowly lobed, the lobes 3-4 on each side, to 0.5 cm long, broadly deltate, apically rounded, the sinuses less than halfway to the midrib; apex acute to obtuse; petioles 1-4 cm long, ca. half as long as the leaf blades, unarmed or with a few prickles, densely stellate pubescent like the stems. Inflorescences 0.3-1 cm long, internodal and lateral, unbranched, with 1-3 flowers, only 1 or 2 flowers open at any one time, pubescent with mixed sessile and short-stalked stellate-porrect trichomes like those of the stems, with multicellular midpoints to 2 mm long, unarmed; peduncle absent to 0.2 cm long; pedicels 2.5-4 cm long, ca. 0.7 mm in diameter at the base, ca. 0.7 mm in diameter at the apex, spreading and slightly nodding at anthesis, unarmed or with a few prickles, more sparsely stellate-pubescent than the inflorescence axes, articulated at the base; pedicel scars tightly spaced ca. 1 mm apart. Buds elongate and tapering, curved, strongly exserted from the calyx before anthesis. Flowers 5-merous, heterostylous and the plants andromonoecious, with the distal flower(s) short-styled and smaller than the hermaphroditic flowers. Calyx with the tube 3.5-4 mm long, conical, sparsely prickly, the lobes 6-8 mm long, ca. 1 mm wide, long-triangular to lanceolate, unarmed, densely stellate-pubescent with mixed sessile and short-stalked porrect-stellate trichomes with multicellular glandular midpoints like those of the pedicels, the pubescence denser than that of the pedicels. Corolla (2-)3.5-5 cm in diameter, violet or deep purple, rotate-stellate, lobed to 1/3 of the way to the base, abundant interpetalar tissue present, the lobes (10-)14-17 mm long, (11-)14-18 mm wide, broad-deltate, spreading or somewhat campanulate at anthesis, mostly glabrous adaxially but with a few stellate trichomes along the petal midvein, densely stellate-pubescent abaxially with densely tangled sessile trichomes where exposed in bud, these densest at the tips, the interpetalar tissue glabrous. Stamens markedly unequal; anthers 3 long and 2 short, the long anthers 12-15 mm long, ca. 2 mm wide, strongly curved and tapering, the short anthers ca. 10 mm long, 0.6-0.7 mm wide, straight or slightly curved, all anthers 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 1-1.5 mm long, glabrous. Ovary conical, glabrous; style ca. 5 mm long in short-styled flowers, 12-15 mm long, in long-styled flowers, strongly curved, glabrous; stigma capitate, the surfaces minutely papillose. Fruit a globose berry, 1-2 per infructescence, 1.1-1.5 cm in diameter, completely enclosed in the accrescent calyx, yellowish brown when ripe, drying and breaking into 4 irregular valves when ripe, the pericarp thin and shiny, glabrous; fruiting pedicels 3-3.5 cm long, 1-1.5 mm in diameter at the base, 3-4.5 mm in diameter at the apex, unarmed, somewhat woody, sharply deflexed and pendent; fruiting calyx strongly accrescent, the lobes often breaking off. Seeds 20-30 per berry, 4-5 mm long, 3-3.5 mm wide, flattened reniform, pale tan or yellowish brown, the surfaces minutely pitted, the testal cells with straight walls, pentagonal in outline, the margins incrassate. Chromosome number: not known.

Distribution

(Fig. 83 ). Solanum wightii is endemic to the mountains of southeastern India in the states of Tamil Nadu and Andhra Pradesh.

Ecology and habitat.

Solanum wightii occurs in dry forests and forest margins, from 850 to 2,200 m elevation.

Common names and uses.

None recorded.

Preliminary conservation status

( IUCN 2019). Vulnerable (VU). EOO (32,261 km2, VU); AOO (44 km2, EN). Solanum wightii is rather narrowly distributed and occurs in open grassy areas subject to human disturbance; it occurs in the proposed Palani Hills National Park, so there is afforded some degree of protection.

Discussion.

Solanum wightii is a beautiful, distinctive Indian endemic with large, zygomorphic flowers and berries enclosed in accrescent calyces that are borne on long, strongly deflexed pedicels. The only other species in India with purple zygomorphic flowers is S. pubescens which has sticky pubescence, smaller flowers with a single long stamen rather than three, and more fruit on each infructescence borne on shorter pedicels. The berry of S. wightii has been recorded as dry and dehiscent (breaks into four valves, Anon. s.n., in MH; described as “subcapsular” in Soosairaj et al. 2021) like members of the Androceras clade ( Whalen 1979) and the Elaeagnifolium clade (see Knapp et al. 2017). Field studies of dispersal in S. wightii are needed; this type of dry berry is also found in members of the Leptostemonum Clade from Australia ( Symon 1981; Martine et al. 2019) where dispersal can be either via a censer (shaking) mechanism or as trample burrs.

Aubriot et al. (2016a) suggest S. wightii is sister to S. praetermissum , but the relationship is poorly supported, and additional analyses are necessary.

Ramachandran and Viswanathan (2010) reported specimens of S. wightii from Sethukadai in the Namakkal District of Tamil Nadu as S. cordatum . The illustration in their paper is clearly of S. wightii although the description appears to be a mixture of information from published works and the specimens they used. The recently described S. pulneyensis ( Soosairaj et al. 2021) clearly falls within the range of variation of S. wightii , and the holotype specimen at RHT corresponds to S. wightii . The character used to distinguish the two species is the dry Solanum pseudo -capsular berry, something that is known to occur in S. wightii (see above).

We have selected the sheet of Wight 1576/126 from Nees van Esenbeck’s personal herbarium (GZU000255932) that is annotated in his handwriting as "S. Wightii n.sp." as the lectotype of S. wightii ; this collection is widely duplicated. After its initial description ( Nees van Esenbeck 1834), Nees van Esenbeck (1836) published a more extensive treatment of S. wightii , in which he clarified his ideas about its relationships and illustrated the plant.

Two collections and two herbaria were cited in the protologue (Van Heurck 1870) of S. hohenackeri - "Hohenacker 1076, 1417! in hb. Van Heurck et hb. DC". The van Heurck herbarium, previously held in Antwerp at AWH, has now been acquired by BR, but sheets are still barcoded with the AWH herbarium code. We have selected duplicate of Hohenacker 1076 held in BR (AWH10071212) as the lectotype for S. hohenackeri ; this specimen is well-preserved and duplicates of Hohenacker 1076 are widely distributed.

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 82. Solanum wightii Nees A herbarium specimen collected in India in 1937 (Vine 176, BM 000900152) B detailed view of a flower (field photograph, unvouchered, India) C detailed view of a fruit (field photograph, unvouchered, India). Photograph credits: A CC-BY, © copyright The Trustees of the Natural History Museum, London B, C G. Gnanasekaran.

Figure 83. Distribution of S. wightii.