Solanaceae Source

A global taxonomic resource for the nightshade family

Solanum linnaeanum

Citation author: 
Hepper & P.-M.L. Jaeger
Citation: 
Kew Bull. 41: 435. 1986.
Type: 
SOUTH AFRICA. Eastern Cape: Somerset Division, Bosch Berg, 5-21 June 1813, W. J. Burchell 3238 (holotype: K! [K000795096]; isotype: GH! [GH00139594]).
Last edited by: 
Sandra Knapp (May 2014)
Written by: 
Maria S. Vorontsova & Sandra Knapp
Habit: 
Erect shrub, 0.4-1.5 m, prickly. Young stems terete, glabrous to moderately stellate-pubescent and prickly, with porrect, sessile or variously stalked trichomes, the stalks to 0.2 mm long, the rays 5-8(-15), 0.1-0.4 mm long, the midpoints 0.1-0.5 mm long, the prickles 3-7 mm long, (0.7-)1.5-2 mm wide at base, straight, narrow-deltate, flattened, pale yellow-orange, glabrous, spaced 3-10 mm apart; bark of older stems glabrescent, pale orange-brown or darker green-brown.
Sympodial structure: 
Sympodial units plurifoliate.
Leaves: 
Leaves simple, the blades (5-)7-13 cm long, (3-)5-9 cm wide, 1.5-2 times longer than wide, elliptic, sometimes ovate or obovate, chartaceous, drying concolorous to discolorous, yellow-green to brown-green; adaxial surface glabrescent, the trichomes with midpoints to 1.7 mm long; abaxial surface sparsely stellate-pubescent to glabrescent, with porrect, sometimes multangulate, sessile trichomes, the rays 5-8(-15), 0.1-0.7 mm long, the midpoints 0.1-1 mm long, with 5-20 prickles on both surfaces; the primary veins 3-4 pairs, the tertiary venation visible on both surfaces; base cuneate or obtuse; margins lobed, the lobes (2-)3-4 on each side, 0.8-3.5 cm long, extending 2/3-3/4 of the distance to the midvein, oblong to obovate or suborbicular, the secondary lobes always present and often well-developed, apically rounded; apex obtuse to rounded; petiole 1-3 cm long, 1/5-1/4 of the leaf blade length, sparsely stellate-pubescent, with 2-6 prickles.
Inflorescences: 
Inflorescences apparently lateral, 2.5-6 cm long, rarely branched, with 4-12 flowers, 1-4 flowers open at any one time, sparsely stellate-pubescent, with 0-8 prickles; peduncle 0-2 mm long; pedicels 1.3-2 cm long in long-styled flowers, 0.5-1 cm long in short-styled flowers, erect, articulated at the base, sparsely stellate-pubescent like the young stem, with 10-20 prickles on long-styled flowers, 0-5 prickles on short-styled flowers; pedicel scars spaced 1-8 mm apart.
Flowers: 
Flowers 5-merous, heterostylous and the plants andromonoecious, with the lowermost flower long-styled and hermaphrodite, the distal flowers short-styled and staminate. Calyx 10-14 mm long in long-styled flowers, 5.5-8 mm long in short-styled flowers, moderately stellate-pubescent, with 30-100 prickles in long-styled flowers and 0-20 prickles in short-styled flowers, the lobes 5-6 mm long in long-styled flowers, 3-4 mm long in short-styled flowers, deltate to ovate, apically acute to rounded. Corolla ca. 3 cm in diameter in long-styled flowers, 1.5-2.5 cm in diameter in short-styled flowers, mauve, stellate, lobed for ca. 2/3 of the way to the base, the lobes 10-14 mm long, 6-8 mm wide in long-styled flowers, 4-12 mm long and 4-7 mm wide in short-styled flowers, broad-deltate, spreading, sparsely stellate-pubescent abaxially, the trichomes porrect, sessile or stalked, the stalks to 0.1 mm, the rays 5-8, 0.1-0.4 mm long, the midpoints reduced or to 1 mm long. Stamens equal, with the filament tube ca. 0.5 mm long, the free portion of the filaments 1-1.5 mm long; anthers 5-7 mm long, connivent, tapering, poricidal at the tips. Ovary glabrous to stellate-pubescent at the apex; style ca. 1.5 cm long in long-styled flowers, thick, almost straight, moderately stellate-pubescent for most of its length.
Fruits: 
Fruit a spherical berry, 1(-3) per infructescence, 2.8-3.3 cm in diameter, the pericarp smooth, dark green with pale green and cream markings when young, yellow at maturity, glabrous; fruiting pedicels 1.3-2.6 cm long, 1.4-2.2 mm in diameter at base, woody, pendulous, with 2-20 prickles; fruiting calyx lobes elongating to 8-15 mm long, ca. 1/4 the length of the mature fruit, reflexed, with 0-100 prickles.
Seeds: 
Seeds ca. 100-200 per berry, 2.5-3.5 mm long, 1.8-3 mm wide, flattened-reniform, dull yellow to orange-brown, the surface smooth, dull, with raised outlines of cells or small pits.
Chromosome number: 

n=12 (voucher: Symon 4710 (ADW); Randell & Symon 1976)

Distribution: 

Native to Africa and found in South Africa and in northern Africa around the Mediterrean; naturalised in disturbed, often coastal, habitats worldwide; sand dunes, grass, forest margins, river banks, and roadsides at 0-1200 m elevation.

 Solanum linnaeanum is one of Australia’s first recorded introduced weeds. It was found by Robert Brown around Port Jackson in 1802. The first Queensland naturalisation (around Brisbane) was recorded by Bailey (1881). In Queensland, it is naturalised in areas south from Gunalda, within about 50 km of the coast, and then on the Eungella plateau west of Mackay. It is also naturalised in New South Wales and occurs in all Australian states except Northern Territory and Tasmania. Australian S. linnaeanum grows on degraded sites, including pasture and roadsides.

Phenology: 
Flowering and fruiting throughout the year.
Phylogeny: 

Solanum linnaeanum is a member of the Old World clade of the spiny solanums (Leptostemonum; Levin et al. 2006); within that it has been shown to belong to the Eggplant clade (Weese & Bohs, 2010; Vorontsova et al. 2013; Knapp et al. 2013), a relationship suggested  by Bean (2004) on morphological grounds.

Commentary: 

Solanum linnaeanum is a striking shrub easy to recognize by its deeply divided (pinnatifid) leaves with a characteristic rounded lobing pattern. Coastal populations in northern Africa and around the Mediterreanean are morphologically uniform but greater variation is observed in South Africa; an unusual form with narrow prickle bases and thin leaves has been collected on the Inhaca Island in Mozambique (Mogg 30894, K). It is not clear if S. linnaeanum is introduced in the Mediterreanean or whether this is a true amphitropical distribution.

The name S. linnaeanum was established to replace the illegitimate and widely misapplied names S. sodomeum L. and S. hermannii Dunal (the former now a rejected name and the latter illegitimate: see Hepper 1978; Hepper & Jaeger 1986). The name “apple of Sodom” is an ancient reference to a plant that grew in the ashes of the site of the Biblical city of Sodom. The fruits of this plant looked edible, but when picked they dissolved into smoke and ashes. The name “apple of Sodom” also refers to Calotropis procera (Aiton) W. T .Aiton in the Apocynaceae, a Middle Eastern plant with large greenish poisonous fruits and fluffy seeds. It is possible the name became attached to S. linnaeanum in pre-Linnaean times due to its spherical, greenish fruits that contain toxic alkaloids. The name “Sodom apple” was probably corrupted to “soda apple,” a vernacular name applied to other spiny yellow-fruited Solanum species such as S. viarum (Mullahey et al. 1998).

Solanum linnaeanum is closely related to the rare South African endemic S. umtuma and can be distinguished by its deeply lobed usually almost pinnatifid leaves with rounded lobes (versus with apically obtuse to acute lobes in S. umtuma).

In describing S. sodomaeum var. mediterraneum, Dunal (1852) cited no specimens, but several illustrations (”Sibthorp, flor. Graec. tab. 235; Lamarck illust. no. 2358, tab. 115, f. 1; S. spinosissimum arborescens Aethiopicum Munt. phyt. cur. fig. 212, bona; S. pomiferum, foliis quercus utrinque spinosis, flore borraginis, Moris. hist. sect. 13, 5ab. 1, fig.”). We have selected the plate from Sibthorp’s Flora Graeca as the lectotype, as it is the only element cited that is clearly of Mediterranean origin. A reproduction of this plate can be found in Strid & Strid’s (2010) annotated edition of the Flora Graeca. Specimens collected by Sibthorp and colleagues can be found at OXF; a typotype sheet could be found there.

References: 


Bailey, F.M. 1881. A few remarks on our naturalised Solanums. Transactions of the Philosophical Society of Queensland 3: 1-4.

Bean, A.R. 2004. The taxonomy and ecology of Solanum subg. Leptostemonum (Dunal) Bitter  (Solanaceae) in Queensland and far north-eastern New South Wales. Austrobaileya 6 (4): 639-816.

Cunningham, G.M., W.E. Mulham, P.L. Milthorpe & J.H. Leigh 1981. Plants of Western New South Wales.
N.S.W. Government Printing Office: Australia.

Dunal, M.F. 1813. Histoire des Solanum, et des genres qui ont été confondus avec eux. Koenig: Paris.

Dunal, M.F. 1852. Solanaceae. Pp. 1-690 in A. P. DeCandolle (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 13(1). Victoris Masson, Paris, France.

Hepper, F.N. 1978. Typification and name changes of some Old World Solanum species.
Botanical Journal of the Linnean Society 76: 287-292.

Hepper, F.N. & P.-M.L. Jaeger 1986. Name changes for two Old World Solanum species. Kew Bulletin 41: 433-435.

Knapp, S., M. S. Vorontsova, and J. Prohens. 2013. Wild relatives of the eggplant (Solanum melongena L.: Solanaceae): new understanding of species names in a complex group. PLoS ONE 8(2): e57039. doi:10.1371/journal.pone.0057039.

Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum). Amer. J. Bot. 93: 157-169.

Linnaeus, C. 1753. Species Plantarum, Facsimile of 1st ed. 1957. The Ray Society: London.

Randell, B.R. & D.E. Symon 1976. Chromosome numbers in Australian Solanum species. Aust. J. Bot. 24: 369-379.

Symon, D.E. 1981. A revision of Solanum in Australia. J. Adelaide Bot. Gard. 4: 1-367.

Van der Most, R. G., Himbeck, R., Aarons, S., Carter, S. J., Larma, I., Robinson, C., Currie, A. & Lake, R. A. 2006. Antitumor efficacy of the novel chemotherapeutic agent coramsine is potentiated by cotreatment with CpG-containing oligodeoxynucleotides. Journal of Immunology 29: 134-142.

Vorontsova, M. S., S. Stern, L. Bohs, and S. Knapp. 2013. African spiny Solanum (subgenus Leptostemonum, Solanaceae): a thorny phylogenetic tangle. Bot. J. Linn. Soc. 173: 176-193. doi:10.1111/boj.12053

Weese, T. L., and L. Bohs. 2010. Eggplant origins: out of Africa, into the Orient. Taxon 59: 49-56.

Common names and uses: 

Local Names. South Africa: Sodom apple (English), this is also the common name through the Mediterranean. 

Uses. Medicinal (van der Most et al. 2006).

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