Solanum nigrescens M.Martens & Galeotti, Bull. Acad. Roy. Sci. Bruxelles 12(1): 140. 1845.

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

33. Solanum nigrescens M.Martens & Galeotti, Bull. Acad. Roy. Sci. Bruxelles 12(1): 140. 1845.

Figs 101 , 102

Solanum nodiflorum Jacq. var. puberulum Dunal, Prodr. [A. P. de Candolle] 13(1): 46. 1852. Type. United States of America. Texas: [Bexar County] "Mexico, Bejar", Oct 1828, J.L. Berlandier 1904 (lectotype, designated by Edmonds 1972, pg. 103 [as holotype]: G-DC [G00144231]; isotypes: MO [acc. # 5481286], NY [00743232], P [P00319514], W [acc. # 0022313]).

Solanum caribaeum Dunal, Prodr. [A. P. de Candolle] 13(1): 48. 1852. Type. Jamaica. Sin.loc., [protologue - "In insulis Caribaeis, Jamaica, Guadalupâ”], no date, Anon. s.n. (lectotype, designated by D’Arcy 1974a, pg. 735: G-DC [G0000144199]).

Solanum crenatodentatum Dunal var. ramosissimum Dunal, Prodr. [A. P. de Candolle] 13(1): 54. 1852. Type. United States of America. Louisiana: "Basse Louisiane", 1839, G.D. Barbe 82 (holotype: P [P00362535]).

Solanum nigrum L. var. nigrescens (M.Martens & Galeotti) Kuntze, Revis. Gen. Pl. 2: 455. 1891. Type. Based on Solanum nigrescens M.Martens & Galeotti.

Solanum nigrum L. var. amethystinum Kuntze, Revis. Gen. Pl. 2: 455. 1891. Type. Costa Rica. San José /Cartago: “Irazu”, 24 Jun 1874, O.E. Kuntze s.n. (neotype, designated here: NY [00688134]).

Solanum prionopterum Bitter, Repert. Spec. Nov. Regni Veg. 11: 5. 1912. Type. Venezuela. Distrito Federal: "Caracas, in arena ad rivulum in valle loci dicti Valle", 25 Mar 1854, J. Gollmer s.n. (holotype: B, destroyed [F neg. 2699], possibly the same original material as the type of S. gollmeri ; no duplicates found).

Solanum gollmeri Bitter, Repert. Spec. Nov. Regni Veg. 11: 202. 1912. Type. Cultivated in Berlin ("horto bot. Berol.") from seeds sent from Caracas, Venezuela by J. Gollmer, 1859, Without collector s.n. (holotype: B, destroyed [F neg. 2689]; lectotype, designated by Knapp et al. 2019, pg. 80: F [V0361922F, acc. # 621268], mounted on sheet with F neg. 2689).

Solanum pruinosum Dunal var. phyllolophum Bitter, Repert. Spec. Nov. Regni Veg. 12: 77. 1913. Type. Cultivated in Europe, seeds from Mexico from David Fairchild as USDA-32065 [protologue "sub. no. 32065, Mexico, S. nigrum "] (no specimens cited, probably described from living plants; original material at B?).

Solanum subelineatum Bitter, Repert. Spec. Nov. Regni Veg. 12: 79. 1913. Type. Cultivated at Bremen from seeds from Mexico sent by U. S. Dept. Agriculture, Bureau of Plant Industry, no. 32067 (original material in Bremen? [destroyed]; possibly described from living material).

Solanum oligospermum Bitter, Repert. Spec. Nov. Regni Veg. 12: 80. 1913. Type. Mexico. Oaxaca: Sierra de San Felipe, 7,500 ft., Oct 1894, C.G. Pringle 4948 (lectotype, designated by Edmonds 1972, pg. 108 [as holotype]: Z [Z000033841]; isolectotypes: BM [BM001017184], BR [BR0000005537983], E [E00570141], GOET [GOET003559], HBG [HBG511469], KFTA [KFTA0000498], NDG [NDG45082], NY [NY00139012], PH [00030459], S [acc. # S-G5704], US [US00027711, acc. # 251984; US01014256, acc. # 1418095], W [acc. # 1895-0004424]).

Solanum durangoense Bitter, Repert. Spec. Nov. Regni Veg. 12: 82. 1913. Type. Mexico. Durango: "prope urbem Durango", Apr 1896, E. Palmer 101 (holotype: B, destroyed; lectotype, designated by D’Arcy 1974a, pg. 738: US [US00027556, acc. # 304231]; isolectotypes: BM [BM001034665], F [V0073093F, acc. # 51213, F. neg. 052464], K [K000063870], MO [MO-568723, acc. # 1718478], NY [00138982]).

Solanum purpuratum Bitter, Repert. Spec. Nov. Regni Veg. 13: 85. 1913. Type. Bahamas. Andros Island: Coppice, near Fresh Creek, Northern Section, 28-13 Jan 1910, J.K. Small & J.J. Carter 8805 (holotype: P [P00369223]; isotypes: F [acc. # 283797], K [K001161011], NY [00111385], US [00027765, acc. # 758168]).

Solanum approximatum Bitter, Repert. Spec. Nov. Regni Veg. 13: 86. 1913. Type. Jamaica. Saint Andrew: Hardwar Gap, 4,000 ft., 17 Jun 1903, G.E. Nichols 89 (holotype: B, destroyed; lectotype, designated by Knapp et al. 2019, pg. 80: NY [NY00111374]; isolectotypes: F [F0073167F, acc. # 147000], GH [GH00077545], MO [MO-503650, acc. # 1815480], US [US00027456, acc. # 429037], YU [YU065289]).

Solanum amethystinum (Kuntze) Heiser, Ceiba 4: 296. 1955. Type. Based on Solanum nigrum L. var. amethystinum Kuntze.

Solanum costaricense Heiser, Ceiba 4: 297. 1955. Type. Costa Rica. Heredia: La Paz, by waterfall, on road to Vara Blanca, about 29 mi. from Heredia, 1,400 m, 13 Sep 1953, C.B. Heiser 3536 (holotype [two sheet holotype]: IND [IND1000067, acc. # 95105; IND1000068, acc. # 95106]; isotypes: CORD [CORD00004189], US [04064608, acc. # 2485189]).

Type.

Mexico. Oaxaca: “Cordillera” ["aux bords des ruiseaux de la cordillera de Yavezia "], Nov-Apr 1848, H. Galeotti 1238 (lectotype, designated by D’Arcy 1974a, pg. 737: P [P00337261]; isolectotypes: BR [BR000000825045, BR0000008250483], W [acc. # 0022312, acc. # 1889-0291397]) .

Description.

Perennial herbs to 3 m high, sometimes epiphytic. Stems terete or more usually angled to ridged, green or sometimes tinged purplish green, usually lax and somewhat scrambling, glabrescent to sparsely pubescent with antrorse simple eglandular uniseriate trichomes to 1 mm long, these white when dry and usually somewhat curved, occasionally on older stems the trichome bases enlarged and forming spinescent processes; new growth more densely pubescent. Sympodial units difoliate, geminate or not, the leaves if paired of similar size and shape. Leaves simple, often shallowly lobed, the blades (1.5)4-10.5(15) cm long, (0.5)2-5(7.5) cm wide, elliptic to elliptic ovate, widest at the middle, membranous, concolorous or somewhat discolorous; surfaces sparsely to moderately pubescent with simple eglandular uniseriate trichomes to 1 mm long, these denser on the veins and abaxially; principal veins 5-6 pairs; base abruptly attenuate, usually decurrent on the petiole; margins entire to sinuate or dentate, the teeth irregular and unevenly spaced, often larger in the basal half of the lamina; apex acute or occasionally acuminate; petiole 0.5-2 cm long, sparsely pubescent like the stems and leaves. Inflorescence internodal, unbranched to occasionally forked, 1-3.5 cm long, with (2)5-10 flowers clustered at the tip (sub-umbelliform) or spaced along the axis (depending on inflorescence age), sparsely pubescent with antrorse simple eglandular trichomes like the stems; flowering-bearing portion 0.3-1 cm long; peduncle 1-2.5 cm long, slender, spreading; pedicels 0.4-0.7 cm long, slender and threadlike, spreading at anthesis, ca. 1 mm in diameter at the base, ca. 0.5 mm in diameter at the apex, sparsely pubescent like the inflorescence axis, articulated at the base. Buds ellipsoid with blunt tips, the corolla strongly exserted from the calyx tube long before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1-1.2 mm, conical, the lobes 0.5-0.8(1) mm long, 0.5-1 mm wide, broadly deltate to deltate, the apices acute or occasionally somewhat rounded. Corolla 0.8-1 cm in diameter, white or less often pale purple, with a green or yellow-green (very occasionally dark purple) central portion near the base of the lobes, stellate, lobed ca. 3/4 of the way to the base, the lobes 3-4 mm long, 1.5-2 mm wide, narrowly triangular, reflexed or spreading, densely papillate abaxially, the papillae ca. 0.1 mm long, denser at the tips and margins. Stamens equal; filament tube minute; free portion of the filaments 0.5-2 mm long, densely pubescent adaxially with tangled simple trichomes; anthers 2-2.8(3) mm long, 1-1.1 mm wide, yellow, ellipsoid or narrowly ellipsoid, poricidal at the tips, the pores lengthening to slits with age. Ovary globose, glabrous; style 3.5-5 mm long, usually somewhat curved, often exserted from the bud before anthesis, exserted beyond the anther cone at anthesis, densely pubescent in the basal 2/3 (the portion inside the anther cone), exserted from the anther cone; stigma minutely capitate, the surface papillose. Fruit a globose berry, 0.6-0.8 cm in diameter, dull green to purplish black at maturity, the pericarp thin and usually matte but sometimes slightly shiny, opaque, glabrous; fruiting pedicels 1-1.2 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, not markedly woody, spreading, not persistent or occasionally remaining on the inflorescence axis; fruiting calyx not accrescent, the tube ca. 1 mm long, the lobes 0.5-1.1 mm long, spreading and appressed to the berry, very occasionally somewhat reflexed. Seeds (5)10-50 per berry, 1.2-1.5 mm long, 1-1.1 mm wide, flattened and teardrop shaped, pale brown to yellow, the surfaces minutely pitted, the testal cells square or pentagonal in shape, becoming elongate and rectangular near the subapical hilum. Stone cells 4-13, mostly commonly 5 or 6, rather large to ca. 0.5 mm in diameter. Chromosome number: n = 12 ( Heiser 1955, voucher Heiser 3536 as S. costaricense ; Heiser et al. 1965, voucher Heiser S106 as S. amethystinum )..

Distribution

(Fig. 103 ). Solanum nigrescens is a widespread species ranging from the southeastern United States of America through Central America, northern South America, and the Caribbean; in South America it occurs in Colombia (Depts. Atlántico, Antioquia, Bolívar, Boyacá, Caldas, Caquetá, Cauca, Cesar, Chocó, Cundinamarca, Huila, La Guajira, Magdalena, Meta, Nariño, Quindio, Risaralda, Santander, Tolima, Valle de Cauca), Ecuador (Provs. Chimborazo, Pichincha, Tungurahua, Zamora-Chinchipe), Venezuela (States of Apure, Aragua, Bolívar, Capital, Carabobo, Delta Amacuro, Lara, Mérida, Miranda, Portuguesa, Sucre, Táchira, Trujillo, Vargas, Yaracuy, Zulia) and the Guianas (Guyana, Suriname, French Guiana).

Ecology and habitat.

Solanum nigrescens is most commonly collected from open areas in cloud forests, deciduous forests and pine forests between sea level and 3,000 m elevation in South America, but most common at lower elevations (ca. 1,500 m).

Common names and uses.

Colombia. Caldas: yerba mora ( Grisales 9); Santander: yerba mora ( López & Gonzáles 31). Ecuador. Azuay: mortiño negro ( Cerón 15905); Cañar: mortiño blanco (Kohn 1469); Chimborazo: hierba mora ( Cerón 15905 [b]). Leaves widely used a potherb ( “quelite”) in Mexico and Central America, but we have not seen this use recorded on South American specimens.

Preliminary conservation status

( IUCN 2022). Least Concern [LC]. EOO = 21,536,739 km2 [LC]; AOO = 4,260 km2 [EN]; calculated on entire species range. Solanum nigrescens is widespread and weedy in the southern United States, throughout Mexico and Central America and in the Caribbean; it also occurs in northern South America. It has been registered as a noxious weed of agriculture in Louisiana ( Orgeron et al. 2018).

Discussion.

Solanum nigrescens is one of the commonest and most widely distributed of all morelloid species in northern South America, Central America and the Caribbean. It is very variable morphologically, perhaps due to its wide ecological tolerance and occurrence in many different habitats. It is sympatric or occurs parapatrically with S. americanum and may hybridise with it in the southeastern United States (see Knapp et al. 2019). Putative hybrids have not been seen from South America.

Where S. nigrescens and S. americanum occur in sympatry, the matte berries with appressed to spreading calyx lobes of S. nigrescens are distinct from the shiny berries with strongly reflexed tiny calyx lobes of S. americanum ; anther length also differs (0.7-1.5 mm in S. americanum versus 2-2.8(3) mm in S. nigrescens ). Solanum nigrescens is also similar and sympatric with S. macrotonum . It differs from that species in its shorter anthers (1-8-2.5 mm long versus (2.7)3-4 mm long) and spreading (versus strongly deflexed) pedicels in fruit. Like most morelloid species, S. nigrescens is very weedy and occupies a wide range of disturbed and undisturbed habitats. Solanum nigrescens is a perennial and has been reported to be epiphytic in some situations ( D’Arcy 1974a, b).

Material identified as S. americanum by Manoko et al. (2007) represents specimens of S. nigrescens ( Särkinen et al. 2018: 61).

Bitter (1914a) reported large numbers of stone cells in the berries of many of the names we consider synonyms of S. nigrescens . In general, S. nigrescens has more stone cells in its berries than do other similar taxa, but these can be difficult to see as some of them are very tiny.

Details of typification of S. nigrescens and its many synonyms can be found in Knapp et al. (2019).

Figures

Figure 101. Solanum nigrescens A new shoot B flower C inflorescence with mature fruit (A-C Ventura 672). Illustration by L. Ribulgo. Previously published in Knapp et al. (2019: 81).

Figure 102. Solanum nigrescens A leaves B flowering branch C inflorescence with flowers at full anthesis D developing fruits (A-D Amith et al. F 0055). Photos by M. Gorostiza Salazar. Previously published in Knapp et al. (2019: 82).

Figure 103. Distribution map of Solanum nigrescens in South America. For distribution in North and Central America and the Caribbean, see Knapp et al. (2019: 84).