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

Knapp, Sandra, Barboza, Gloria E., Bohs, Lynn & Saerkinen, Tiina, 2019, A revision of the Morelloid Clade of Solanum L. (Solanaceae) in North and Central America and the Caribbean, PhytoKeys 123, pp. 1-144 : 92-97

16. Solanum scabrum Mill., Gard. Dict. ed. 8, no. 6. 1768 Figures 48 , 49

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.7

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 tall, often woody at the base. Stems terete, ridged, or winged, green to purple, erect or ascending, if ridged or winged the stems later spinescent, 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 pseudospines. Sympodial units difoliate, the leaves usually not geminate, but if leaves paired then one is usually smaller. Leaves simple, 4-15(20) cm long, 3-10(16) cm wide, broadly ovate to elliptic, very variable in size depending on cultivars and growth conditions, green to dark green above to somewhat purple coloured, slightly paler; adaxial and abaxial surfaces glabrous or sparsely pubescent with simple uniseriate trichomes like those on the stem mainly along veins and scattered along lamina; major 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 1-2 (-4) cm long, internodal, unbranched, forked or many times branched (in cultivars), with 4-10(30+) flowers clustered towards the tips (sub-umbelliform) or spread along the rhachis, 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 rhachis, spaced 0-2 mm apart, sometimes with short stumps ca. 0.5-1.0 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, all perfect. 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 7-12 mm 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, densely pubescent with simple uniseriate trichomes 0.2-0.5 mm long in the basal 1/2 where included in the anther cone, exserted 0-1.5 mm beyond the anther cone; stigma capitate, the surface minutely papillate. Fruit a globose to slightly flattened berry, 10-20 mm in diameter, purplish black at maturity, opaque, the pericarp thick, shiny; fruiting pedicels 7-15(20) mm long, 0.5-1 mm in diameter at the base, 1.1-1.5 mm in diam eter at the apex, stout, erect and spreading, purple or brown, usually not falling with the fruit, remaining on the plant and often persistent 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 tear-drop 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: 2n =6 × =72 (see Särkinen et al. 2018).

Distribution.

(Figure 50 ) Solanum scabrum is native to tropical Africa; introduced worldwide as a cultivated plant.

Ecology.

In the Americas only known from cultivation, although plants could persist in subtropical areas.

Common names.

United States of America. Garden huckleberry ( Heiser 1969).

Uses.

Berries used for jam (in Africa leaves also consumed as spinach).

Preliminary conservation status ( IUCN 2017).

Least Concern (LC). Solanum scabrum is only known from cultivation in North America; for conservation status in its native range see Särkinen et al. (2018).

Discussion.

Solanum scabrum is a species known only from cultivation in North and Central America and the Caribbean. It is the mostly commonly cultivated morelloid species in Africa, and there is used from both its leaves (eaten as spinach) and its fruits. Specimens of S. scabrum occasionally have been collected from areas where enslaved people were brought from western Africa (e.g., Bahia, Brazil), so it is possible it could occur in especially the Caribbean.

Solanum scabrum can be distinguished from the somewhat similar S. americanum by the larger anthers (2.5-3.0 mm long versus 0.8-1.5 mm long) that usually dry a dirty brownish tan. In both these species, as well as S. retroflexum , the berries drop off without the pedicels at maturity, and lack stone cells except in some populations of S. americanum where up to 4 stone cells have been observed (other populations lacking stone cells completely). Both S. scabrum and S. americanum have purple-black, shiny berries, while S. retroflexum has matte, waxy looking purple berries (with a bloom like blueberries, Heiser 1969).

Material seen from North America represents only a fraction of the diversity of S. scabrum across its native range in Africa and is largely composed of specimens of large berried cultivars with simple inflorescences. The cultivated plants are sold in the garden trade in United States of America under the names of 'garden huckleberry’. The origin and identity of this garden plant gained huge interest in the 1960's ( Soria and Heiser 1959, 1961).

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

Specimens examined.

See Suppl. materials 1 and 3.

Figures

Figure 48. Solanum scabrum Mill. 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). Scale bars: 4 cm (A, D); 3.3 mm (B); 1.5 cm (C, F); 7 mm (E); 2 mm (G). Drawing by L. Smith (previously published in " PhytoKeys 106 ").

Figure 49. Solanum scabrum Mill. A Common habit B habit in taller varieties C flowers of the larger berried variety at full anthesis D fruits of a larger berried variety E flowers of the smaller berried variety at full anthesis F Fruits of a smaller berried variety (A Nijmegen accession BG 13 B Nijmegen accession A 34750072 C Nijmegen accession GB 22 D Nijmegen accession H 065 E Nijmegen accession A 34750067 F Nijmegen accession 2010 / 3). Photos by S. Knapp (previously published in " PhytoKeys 106 ").

Figure 50. Distribution of Solanum scabrum Mill. (specimens mapped are all cultivated).