Solanum palitans C.V.Morton, Revis. Argentine Sp. Solanum 92. 1976.

Knapp, Sandra, Saerkinen, Tiina & Barboza, Gloria E., 2023, A revision of the South American species of the Morelloid clade (Solanum L., Solanaceae), PhytoKeys 231, pp. 1-342 : 1

35. Solanum palitans C.V.Morton, Revis. Argentine Sp. Solanum 92. 1976.

Figs 107 , 108

Type.

Argentina. Tucumán: Dpto. Tafí del Valle, Yerba Buena , 19 Jan 1919, S. Venturi 159 (holotype: US [00027724, acc. # 1548805]; isotypes: BA [acc. # 2463], LIL [LIL001454], LP [ LP010926 ], MA, SI [003329]) .

Description.

Annual, decumbent or prostrate herbs, the young plants sometimes erect, up to 0.2 m high often rooting at the lower nodes, forming dense patches, the branches to ca. 1 m long. Stems decumbent or ascending, terete or somewhat angled with ridges, green, older stems yellowish-brown, not markedly hollow; new growth pubescent with simple, spreading, uniseriate, translucent, eglandular trichomes, these 0.5-1 mm long, glabrous or nearly so; older stems glabrous. Sympodial units difoliate, the leaves not geminate. Leaves simple and strongly 3-lobed, the blades 2.5-9 cm long, 2.5-7.5 cm wide, broadly ovate, widest in the lower third, thinly membranous, concolorous, without smell; adaxial surfaces glabrous to sparsely pubescent with simple hairs to 0.5 mm on the major veins; abaxial surfaces glabrous; major veins 3-4 pairs; base long attenuate, decurrent on the petiole; margins 3-lobed nearly to the midrib, rarely the lateral lobes themselves lobed, the terminal lobe ovate, the lateral lobes asymmetrically ovate or lanceolate-ovate, acute at the tips, the sinuses sometimes sparsely ciliate; apex acute; petioles 0.5-2 cm, winged to the base, glabrous or sometimes sparsely ciliate near the base. Inflorescences internodal or often just below a node, unbranched or rarely forked, 1.2-2.5 cm long, with 4-9 flowers, glabrous to sparsely pubescent; peduncle 0.7-1.4 cm long, delicate; pedicels 3-5 mm long, 0.2-0.3 mm in diameter at the base and at the apex, filiform, spreading, articulated at the base; pedicel scars spaced 1-5 mm apart. Buds ellipsoid, the corolla completely covered by the calyx tube before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1.5-2 mm long, cup-shaped, the lobes ca. 0.75-1.5 mm long, lanceolate-oblong, glabrous, the tips acute. Corolla ca. 0.7 cm in diameter, white or rarely light violet, rotate-stellate, lobed ca. 1/2 way to the base, the lobes 1.5-2.5 mm long, 1-2 mm wide at the base, reflexed or spreading at anthesis, abaxially minutely white-puberulent on the tips of the lobes, glabrous adaxially. Stamens equal; filament tube minute; free portion of the filaments 0.5-1 mm long, adaxially pubescent with tangled uniseriate trichomes; anthers 1.6-2 mm long, 0.7-0.8 mm wide, oblong or ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age and drying. Ovary glabrous; style 2.3-3.3 mm long, straight exserted beyond the anther cone, glabrous or sparsely pubescent in the lower part,; stigma capitate, the surface minutely papillate, green in live plants. Fruit a depressed-globose and bilobed (especially when young) berry, 0.6-0.8 cm in diameter, pale yellow, the pericarp thin and somewhat shiny, opaque to somewhat translucent, glabrous; fruiting pedicels 4-7 mm long, 0.5-0.7 mm in diameter at the base, 0.5-0.7 mm in diameter at the apex, spreading, recurved at the base to hold the fruit downwards, often in contact with the soil, not persistent; fruiting calyx not markedly accrescent but the lobes somewhat elongating in fruit, the tube 2-3 mm long, the lobes 2-3(-4) mm long, covering the basal 1/3 of the berry, the tips somewhat recurved. Seeds 20-30 per berry, 1.5-1.6 mm long, 1.2-1.6 mm wide, flattened reniform, light yellow, the surfaces pitted, the testal cells sinuate in outline. Stone cells 2(-4) per berry, 2 larger and apical (1-1.5 mm in diameter), the other 2 equatorial, smaller, 0.5-0.6 mm in diameter, all pale cream-coloured. Chromosome number: n = 12 ( Moyetta et al. 2013, voucher Barboza et al. 2228, as S. tripartitum , Barboza et al. 2178).

Distribution

(Fig. 109 ). Solanum palitans occurs in northwestern Argentina (Provs. Catamarca, Córdoba, Jujuy, Salta, Tucumán), northern Chile and Bolivia (Depts. Chuquisaca, Cochabamba, La Paz, Potosi, Santa Cruz); a very local naturalised population is known from New South Wales (Australia, see Särkinen et al. 2018).

Ecology and habitat.

Solanum palitans grows in disturbed sites, along roadsides and field margins, on rocky, sandy, or clay soils; between (50-)1,400 and 3,000(-3,700) m elevation.

Common names and uses.

Argentina. Jujuy, Tucumán: ñusco ( Hilgert and Gil 2006; Ceballos and Perea 2014; Acosta et al. 2018); Salta: ñusco blanco ( Califano 2020). Leaves are used medicinally to soothe pain from blows and as a febrifuge ( Ceballos and Perea 2014), and as animal fodder ( Califano 2020).

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 1,008,132 km2 [LC]; AOO = 468 km2 [EN]; calculated excluding adventive Australian range. Solanum palitans is a widespread species in its native range. It grows in open disturbed areas and has been collected in at least one protected area in Argentina (e.g., Parque Nacional Calilegua).

Discussion.

Solanum palitans is morphologically similar to S. tripartitum and closely related to it ( Särkinen et al. 2015b) The two species are sympatric and will apparently hybridise in the field (see below). With S. corymbosum and S. radicans , these two taxa form the distinct Radicans clade ( Särkinen et al. 2015b), distinguished by their usually divided leaves and bright orange or red berries. Solanum palitans has a creeping habit, with stems growing close to the ground extending up to 3 m and often rooting at nodes. Solanum tripartitum is an upright plant, the base not rooting if decumbent, with erect and branched inflorescences. Solanum palitans has unbranched inflorescences, whereas those of S. tripartitum are usually branched several times. The berries of S. palitans are yellow or pale yellow and often held near the soil surface, while those of S. tripartitum are bright red when ripe and not so disposed. Both species have two large apical stone cells in the berries.

Solanum palitans is very easily confused in the herbarium with S. tripartitum and the species are mixed under the same collection number in some cases. There are apparently hybrids, at least in Bolivia, between the two taxa. Michael Nee (pers. comm.) selected forty individual plants more or less at random from an area of ruderal vegetation on dry rocky slopes and gravelly stream beds in Achumani, a suburb of the City of La Paz, Bolivia; 25 proved to be S. tripartitum (Nee 32057a-y), 11 were S. palitans (Nee 32058a-k), and four seemed to be intermediate (Nee 32058a-d). The plants of Nee 32058a-d were similar to S. palitans , but had the branched inflorescences of S. tripartitum . Nee & Solomon 34175 has also been suggested to be a hybrid plant by M. Nee (pers. comm.).

Solanum radicans differs from both S. palitans and S. tripartitum in its 5-lobed leaves, in its combination of a generally upright habit and orange or orange-yellow berries and its more northerly distribution. Solanum corymbosum has entire leaves.

Figures

Figure 107. Solanum palitans A habit B flower C stamen, ventral view D gynoecium E fruit (A-E voucher details missing). Illustration by M. T. Cabrera. Previously published in Barboza et al. (2013: 252).

Figure 108. Solanum palitans A habit B leaves C flowers and inflorescence D fruits at different stages of maturity (A-D Barboza et al. 3471). Photos by T. Saerkinen.

Figure 109. Distribution map of Solanum palitans. For adventive distribution in Australia, see Saerkinen et al. (2018).