Solanum scabrum Mill., Gard. Dict. ed. 8, no. 6. 1768.

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

52. Solanum scabrum Mill., Gard. Dict. ed. 8, no. 6. 1768.

Figs 158 , 159

Solanum fistulosum Dunal, Encycl. [J. Lamarck & al.] Suppl. 3: 749. 1814. Type. "Originaire de l’Isle de France [Mauritius], est cultivée en Amerique [Brazil]", Herb. Richard s.n. (lectotype, designated by D’Arcy 1974a, pg. 735: P [P00335259]).

Solanum oleraceum Dunal var. macrocarpum Dunal, Prodr. [A. P. de Candolle] 13(1): 50. 1852. Type. Brazil. Bahia: Ilheus, 1841, C.F.P. Martius 1255 (lectotype, designated by Edmonds 1972, pg. 108 [as holotype]: G-DC [G00144295]; isolectotype: P [P00366815]).

Type.

Cultivated in Chelsea Physic Garden , said in protologue to "grow naturally in North America", Herb. Miller s.n. (lectotype, designated by Henderson 1974, pg. 61 [as type]: BM [BM000847083]) .

Description.

Annual or short-lived perennial herbs to 1.5 m high, often woody at the base. Stems terete, ridged, or winged, green to purple, erect or ascending, if ridged or winged the stems later with spinose processes, usually somewhat hollow; new growth puberulent with simple spreading uniseriate 2-8-celled eglandular trichomes 0.3-0.8 mm long; older stems glabrescent, with or without prominent spinose processes. Sympodial units difoliate, the leaves usually not geminate, but if leaves paired, then one is usually smaller. Leaves simple to rarely shallowly sinuate, the blades 4-15(20) cm long, 3-10(16) cm wide, broadly ovate to elliptic, widest in the lower half, very variable in size depending on cultivars and growth conditions, membranous, usually discolorous; adaxial and abaxial surfaces glabrous or sparsely pubescent with simple uniseriate trichomes like those on the stem mainly along veins and scattered along lamina; principal veins 3-6(-8) pairs, paler green or often purple tinged; base abruptly acute or truncate, narrowly winged onto the petiole; margins entire or rarely shallowly sinuate; apex rounded to acute; petioles 1-5(8) cm long, glabrous or sparsely pubescent with simple uniseriate trichomes like those of the stem. Inflorescences internodal, unbranched, forked or many times branched (in cultivars), 1-2 (-4) cm long, with 4-10(30+) flowers clustered towards the tips (sub-umbelliform) or spread along the axis, glabrous or sparsely pubescent with simple uniseriate trichomes like those on the stem; peduncle 1-5(-8) cm long, erect and thick, much thickened at the apex, subwoody, green or purple-tinged; pedicels 0.4-1 cm long, 0.3-0.5 mm in diameter at the base, 0.75-0.9 mm in diameter at the apex and abruptly expanding to the calyx tube, stout, erect and/or spreading, green or purple-tinged, glabrous or minutely pubescent like the peduncle, articulated at the base; pedicel scars tightly clustered near the tip of the axis, spaced 0-2 mm apart, sometimes with short stumps ca. 0.5-1 mm long. Buds globose to subglobose, the corolla exserted 1/2-1/3 from the calyx tube before anthesis. Flowers 5-merous or occasionally fasciate and 6-7-merous in cultivars, cosexual (hermaphroditic). Calyx tube 0.9-1.1 mm long, abruptly cup-shaped with a broad base, the lobes slightly unequal, 0.9-1.5 mm long, 0.5-1.5 mm wide, broadly deltate with a rounded tip, green or purple-tinged, glabrous or sparsely pubescent with simple uniseriate trichomes like those of the pedicels, the margins often drying scarious and white. Corolla 0.7-1.2 cm in diameter, white, purple-tinged or occasionally lilac to dark purple, with a yellow basal star, stellate, lobed ca. 1/2 of the way to the base, the lobes 2.5-4 mm long, 1.5-3 mm wide, spreading or reflexed, densely papillate on tips and margins. Stamens equal; filament tube very short, to 0.1 mm long; free portion of the filaments 0.5-0.8 mm long, glabrous or pubescent with tangled uniseriate simple trichomes; anthers 2-3 mm long, ellipsoid or slightly tapering towards the tips, yellow, orange or brown, poricidal at the tips, the pores lengthening to slits with age and drying, the connective often becoming brownish black in dry specimens. Ovary rounded, glabrous; style 2.5-5 mm long, straight, exserted beyond the anther cone, densely pubescent with simple uniseriate trichomes 0.2-0.5 mm long in the basal 1/2 where included in the anther cone; stigma capitate, the surface minutely papillate. Fruit a globose to slightly flattened berry, 1-2 cm in diameter, purplish black at maturity, the pericarp thick, shiny, opaque, glabrous; fruiting pedicels 0.7-1.5(2) cm long, 0.5-1 mm in diameter at the base, 1.1-1.5 mm in diameter at the apex, stout, erect and spreading, purple or brown, usually not falling with the fruit, persistent, remaining on the plant on older inflorescences; fruiting calyx not accrescent, the tube 1.5-2 mm long, usually tearing unevenly, the lobes 2-3 mm long, usually with thicker white margins in dry material, appressed or spreading to slightly reflexed. Seeds (20-)100-150 per berry, 2-2.8 mm long, 1.5-1.8 mm wide, flattened and teardrop shaped with a subapical hilum, yellow-brown or purple, the surfaces minutely pitted, thin and the embryo clearly visible, the testal cells rectangular to pentagonal in outline. Stone cells absent. Chromosome number: 2 n = 72 (see Särkinen et al. 2018).

Distribution.

Solanum scabrum is native to tropical Africa and has been introduced worldwide as a cultivated plant as a result of trafficking in enslaved peoples. In South America, apart from the type of S. fistulosum , we have only seen two collections, both from Brazil (States of Bahia, Rio de Janeiro), one of these (Amorim 21) cultivated in the Jardim Botânico do Rio de Janeiro and the other (Martius 1255) of uncertain origin. A map of the native distribution of S. scabrum can be seen in Särkinen et al. (2018: 151, Fig. 48 ).

Ecology and habitat.

Solanum scabrum is only known from cultivation in South America, although plants could persist in subtropical areas.

Common names and uses.

In its native range S. scabrum is a prized plant for its juicy berries and its nutritious leaves that are used as a potherb (see Särkinen et al. 2018 for a summary of the uses of S. scabrum ).

Preliminary conservation status

( IUCN 2022). We have not assessed S. scabrum for South America since it is only cultivated here; for conservation status in its native range in Africa see Särkinen et al. (2018).

Discussion.

Solanum scabrum is a species known only from cultivation in the Americas. It is the mostly commonly cultivated morelloid species in Africa, and there is used for both its leaves (eaten as a potherb) and its fruits. Specimens of S. scabrum occasionally have been collected from areas where enslaved people were brought from western Africa (e.g., Bahia, Martius 1255), so it is possible it could occur elsewhere in the region.

Solanum scabrum can be distinguished from the somewhat similar S. americanum by the larger anthers (2.5-3 mm long versus 0.8-1.5 mm long) that usually dry a dirty brownish tan. In both these species the berries drop off without the pedicels at maturity and lack stone cells except in some populations of S. americanum where up to four stone cells have been observed (other populations lacking stone cells completely). Both S. scabrum and S. americanum have purple-black, shiny berries.

Material seen from South America represents only a fraction of the diversity of S. scabrum across its native range in Africa (see Olet 2004; Olet et al. 2006; Manoko 2007) and are specimens of cultivars with simple inflorescences, possibly originally brought for use as vegetables or fruits.

Typification details for the synonyms of S. scabrum , and a complete discussion of its morphological variability and many uses in its native range can be found in Särkinen et al. (2018).

Figures

Figure 48. Solanum echegarayi A habit B underground woody rhizomes C flowers at anthesis D immature and mature fruits (A, C, D Barboza et al. 4783 B Knapp et al. 10540). Photos by G. E. Barboza and S. Knapp.

Figure 158. Solanum scabrum A habit of wild form B flower of wild form C infructescence of wild form D habit of cultivated form E inflorescence of cultivated form F fruit of cultivated form G seed (A-C Pilz 2108 D-G Nee 16088). Illustration by L. Smith. Previously published in Saerkinen et al. (2018: 148) and Knapp et al. (2019: 113).

Figure 159. Solanum scabrum A common habit B habit in taller varieties C flowers of the larger berried variety at full anthesis D fruits of a large-berried morph E flowers of the small-berried morph at full anthesis F fruits of a small-berried morph (A Nijmegen acc. # BG 13 B Nijmegen acc. # A 34750072 C Nijmegen acc. # GB 22 D Nijmegen accession H 065 E Nijmegen acc. # A 34750067 F Nijmegen acc. # 2010 / 3). Photos by S. Knapp. Previously published in Saerkinen et al. (2018: 149) and Knapp et al. (2019: 114).