Solanum pyracanthos

Citation author:

Lam.

Citation:

Tabl. Encycl. 2: 21, no. 2364. 1794.

Type:

MADAGASCAR. Sin. loc., J. Martin s. n. (lectotype, designated by Vorontsova & Knapp Syst Bot Monog in press: P-LA! [P00357689]; possible isolectotype: P-L!A [P00357690]).

Last edited by:

Sandra Knapp (May 2014)

Written by:

Maria S. Vorontsova & Sandra Knapp

Habit:

Erect shrub, 0.7-1 m, prickly. Young stems terete, sparsely stellate-pubescent and prickly, with porrect, variously stalked trichomes, the stalks 0.1-0.2 mm long, the rays 6-8, 0.2-0.5 mm long, the midpoints ca. same length as the rays or up to 0.4 mm, the prickles 8-15 mm long, 0.3-1.5 mm wide at base, straight, conical, perpendicular to the stem, sometimes retrorse, bright red-orange, glabrous, spaced 1-6 mm apart; bark of older stems glabrescent, brown.

Sympodial structure:

Sympodial units plurifoliate.

Leaves:

Leaves simple, the blades 6-21 cm long, 2-6(-9) cm wide, ca. 3 times longer than wide, elliptic, chartaceous, drying weakly discolorous, yellow-green to red-green with red-orange venation, moderately stellate-pubescent on both surfaces, with porrect stalked trichomes, the stalks 0.1-0.2 mm long, the rays 7-8, 0.15-0.5 mm long, the midpoints shorter than the rays, with 10-50 prickles on both surfaces; the primary veins 7-9 pairs, the tertiary venation usually visible abaxially but not adaxially; base cordate to truncate; margins lobed, the lobes (3-)5-9 on each side, 0.8-4 cm long, extending 2/3-3/4 of the distance to the midvein, deltate to lanceolate, often with secondary lobing, apically acute, sometimes rounded; apex acute to acuminate; petiole 1-4.5 cm long, 1/4-1/3 of the leaf blade length, sparsely stellate-pubescent, with (0-)2-8 prickles.

Inflorescences:

Inflorescences apparently terminal or lateral, 5-6 cm long, not branched, with 5-10 flowers, 2-4 flowers open at any one time, moderately stellate-pubescent, with 0(-2) prickles; peduncle 5-20 mm long; pedicels 1-1.6 cm long, erect, articulated at the base, moderately stellate-pubescent, unarmed; pedicel scars spaced 2-6 mm apart.

Flowers:

Flowers 4-5-merous, usually all perfect, occasionally with a few short-styled flowers at the inflorescence apex. Calyx 8-11 mm long, moderately stellate-pubescent, with 0-20 prickles, the lobes ca. 5 mm long, narrow-deltate, apically long-acuminate. Corolla 2.3-3 cm in diameter, mauve to purple, stellate, lobed for 1/3-1/2 of the way to the base, the lobes 5-7 mm long, 6-10 mm wide, broad-deltate, apically cuspidate, spreading, sparsely stellate-pubescent abaxially, the trichomes porrect, stalked, the stalks 0.1-0.2 mm, the rays 6-8, 0.2-0.5 mm long, the midpoints ca. same length as the rays or to 0.4 mm long. Stamens equal, with the filament tube ca. 2 mm long, the free portion of the filaments ca. 1 mm long; anthers 6-7 mm long, connivent, tapering, poricidal at the tips. Ovary stellate-pubescent in the upper 1/4; style 1.3-1.4 cm long, slender, almost straight, moderately stellate-pubescent for most of its length.

Fruits:

Fruit a spherical berry, 2-5 per infructescence, 1-1.2 cm in diameter, the pericarp smooth, yellow at maturity, glabrous; fruiting pedicels 1.4-2 cm long, 0.9-1.5 mm in diameter at base, woody, pendulous, with 0(-5) prickles; fruiting calyx lobes elongating to 10-14 mm long, 1/2-2/3 the length of the mature fruit, reflexed with 0-20 prickles.

Seeds:

Seeds ca. 20-30 per berry, 1.9-2.8 mm long, 1.6-2.1 mm wide, flattened-reniform, dull yellow to orange-brown, the surface finely pitted, the middle of seed almost smooth, the pit size increasing towards the edges of the seed.

Chromosome number:

2n=24 (Federov 1969)

Distribution:

Southeastern Madagascar; dry scrub and roadsides; 0–500 m elevation.

Phylogeny:

Solanum pyracanthon was one of the first three spiny Solanum species from Madagascar to be included in molecular phylogenetic studies (Bohs, 2005) and is a member of the Old World clade of subgenus Leptostemonum (Levin et al. 2006). It belongs to the somewhat well-supported Madagascar Clade of Vorontsova et al. (2013), in a group with Solanum erythracanthum and Solanum myoxotrichum.

Commentary:

Solanum pyracanthos is a striking ornamental species with prominent orange prickles and dark orange to red venation on the leaves that creates a bright contrast with green leaves, vivid purple flowers and yellow anthers. Solanum pyracanthos attracted the attention of science about 50 years earlier than any other species of Solanum from Madagascar. It was grown from seed at the Paris Botanical Gardens before Lamarck described it in 1794. Attention of the horticultural trade was captured, and the species became widely cultivated. Color illustrations of S. pyracanthos were published by Jacquin (1804) from a plant of unknown origin at the Schoenbrunn Gardens in Austria, by Wendland (as S. runcinatum, 1798) from a plant recorded as originating from India, and by Smith (1804) from a plant cultivated in Britain. It is still widely grown for ornament in the northern hemisphere, often in glasshouses or as a seasonal shrub in more temperate areas.

Solanum pyracanthos is a morphologically uniform species unlikely to be confused with another taxon. Its closest relative is most likely S. erythracanthum because of their shared simply lobed leaves and tendency towards reddish indumentum. Solanum pyracanthos is more robust and woody, with mature leaves often resembling those of dandelions (Taraxacum, Asteraceae), and larger fruit than S. erythracanthum.

The specific epithet was originally published as “pyracanthos,” a Greek noun in apposition not correctable to an adjective; the alternative forms “pyracanthon” and “pyracanthum” are thus incorrect.

Of the two specimens of S. pyracanthos in the Lamarck herbarium we have chosen (P00357689) as the lectotype, despite it only having fruit and buds. The other sheet (P00357690) and possible isolectotype has open flowers, but does not have an label linking it to the protologue. The leaves of both specimens are very similar, however, and are likely from the same plant.

References:

Bohs, L. 2005. Major clades in Solanum based on ndhF sequences. Pp. 27-49 in R. C. Keating, V. C. Hollowell, & T. B. Croat (eds.), A festschrift for William G. D’Arcy: the legacy of a taxonomist. Monographs in Systematic Botany from the Missouri Botanical Garden, Vol. 104. Missouri Botanical Garden Press, St. Louis.

D’Arcy, W.G., & A. Rakotozafy 1994. Solanaceae. Famille 176, pp. 1-146. In Flore de Madagascar et des Comores, P. Morat (ed.). Muséum National D’Histoire Naturelle, Paris.

Federov, A.A. 1969. Chromosome numbers of flowering plants. 926 pp. Academy of Sciences U.S.S.R., Moscow.

Jacquin, N.J. 1804. Plantarum rariorum horti caesarei schoenbrunnensis descriptiones et icones. C. F. Wappler, Vienna.

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

Smith, J.E. 1804. Exotic botany: consisting of coloured figures, and scientific descriptions, of such new, beautiful, or rare plants, as are worthy of cultivation in the gardens of Britain; with remarks on their qualities, history, and requisite modes of treatment. Volume two. R. Taylor and Co., London.

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

Wendland, J.C. 1798. Botanische Beobachtungen, nebst einigen neuen Gattungen und Arten. Gebrüdern Hahn, Hannover.

Common names and uses:

Local Names. Madagascar: Kokomba, rohingivy, vangivy, vontaka (D’Arcy and Rakotozafy 1994).
Uses. Ornamental plant cultivated in glasshouses worldwide.

Taxonomic name:

Solanum pyracanthos (Solanaceae)

Solanaceae Source

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Solanum pyracanthos

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