Solanum commersonii

Citation author:

Dunal

Citation:

in Poiret, Encycl. Suppl. 3: 746. 1814.

Type:

Uruguay. Montevideo: beach at the foot of the hill [“la plague de pied du morne de Montevideo”], May 1767, P. Commerson 47 (lectotype, P00325546 [Morton neg. 3694, or Hawkes unnumbered neg., G, NY], designated by Hawkes & Hjerting, 1969: 147; isolectotypes, C, does not bear the number 47 but assumed to be part of type collection [Correll neg. 965 or F neg. 22878, F, LL, MEDEL, MO, NY, UC1152252], P00325545, P [G neg. 39157, G], drawing GOET [Correll neg. 610, F, LL, MO, NY, UC1152251]).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M. & A. Clausen

Habit:

Herbs 0.15-0.3 m tall in sunny situations, but in shady situations of woodlands or among tall grasslands up to 1 m tall, semi-rosette when low-growing to erect. Stems 1-3 mm in diameter at base of plant, green, unwinged, glabrous to densely puberulent; tubers typically placed one at the end of each stolon.

Sympodial structure:

Sympodial units tri- to plurifoliate, not geminate.

Leaves:

Leaves odd-pinnate, the blades 6.5-14.5 x 3.3-7.8 cm, green, membranous to chartaceous, glabrous to pubescent adaxially and abaxially with hairs like those of the stems; lateral leaflet pairs 2-5, markedly unequal, decreasing greatly in size toward the leaf base; most distal lateral leaflets 1-3.8 x 0.7-2 cm, narrowly to broadly ovate, the apex acuminate, the base typically oblique, or cordate, to rounded, subsessile and slightly decurrent or with petiolules up to 2 mm long; terminal leaflet 3.8-8.3 x 2.3-4 cm, broadly ovate to broadly elliptic, the apex obtuse to more rarely acute, the base cuneate; interjected leaflets 0-3, sessile to short petiolulate, ovate to orbicular; petioles 0.9-2.8 cm, pubescent as the stems. Pseudostipules absent to 1 mm long, pubescent with hairs like those of the stem.

Inflorescences:

Inflorescences 2-15 cm, terminal with a subtending axillary bud, generally in distal half of the plant, usually forked, with 3-12 flowers, with all flowers apparently perfect, the axes glabrous or densely puberulent like the stem; peduncle 1.5-6.5 cm long; pedicels 10-30 mm long in flower and fruit, spaced 1-10 mm apart, articulated at about the middle.

Flowers:

Flowers homostylous, 5-merous. Calyx 3-7 mm long, the tube 1-2 mm, the lobes 1-6 mm, acute to attenuate, the acumens 1-2 mm long, glabrous or pubescent with hairs like those of the stem. Corolla 2-3 cm in diameter, stellate to deeply stellate, violet or sometimes white tinged with violet, the tube 1-2 mm long, the acumens absent or to 2 mm long, the corolla edges flat, not folded dorsally, glabrous adaxially, minutely puberulent abaxially, especially along the midribs, ciliate at the margins, especially at the tips of the corollas. Stamens with the filaments 1-2 mm long; anthers 4-5 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 9-12 mm x ca. 1 mm, exceeding stamens by 2-5 mm, straight, glabrous; stigma clavate to capitate.

Fruits:

Fruit an ovoid to conical berry, 2.5-3 cm long, 2-2.5 cm wide, green when ripe, glabrous.

Seeds:

Seeds from living specimens ovoid and ca. 2 mm long, whitish to greenish in fresh condition and drying brownish, with a thick covering of “hair-like” lateral walls of the testal cells that make the seeds mucilaginous when wet, green-white throughout; testal cells honeycomb-shaped when lateral walls removed by enzyme digestion.

Chromosome number:

2n = 3x = 36 voucher missing = (Hijmans, et al. 2007)
2n = 2x = 24 voucher: Okada 4583 (BAL) (Hijmans, et al. 2007)

Distribution:

Solanum commersonii is widely distributed in southern Brazil, Uruguay, and northeastern Argentina; sandy dunes near the coast, dense grasslands, in woods (low woods as well as among Araucaria angustifolia and palm trees, Butia yatay) at the foot of low hills, sea shore, in harvested fields and roadsides; from sea level to 400 m.

Phenology:

Flowering and fruiting from October to July.

Phylogeny:

Solanum commersonii is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, Solanum commersonii is a member of a distinctive group of species formerly classified in series Conicibaccata (see below). On a higher taxonomic level, it is a member of the informally-named Potato Clade, a group of perhaps 200-300 species that also includes the tomato and its wild relatives (Bohs, 2005).

Commentary:

Solanum commersonii overlaps in distribution with morphologically similar S. malmeanum and S. chacoense. From S. malmeanum it can be differentiated by the uppermost lateral leaflets decreasing rapidly toward the base, shorter lateral leaflets and the violet (not white) corolla color. From S. chacoense it can be differentiated by its smaller plant habit, the lateral leaflets decreasing rapidly toward the leaf base, the larger terminal leaflet, the lower number of lateral leaflets and violet (not white) flower color.

Hawkes and Hjerting (1969) and Hawkes (1990) considered S. malmeanum and S. commersonii as subspecies of commersonii and distinguished subsp. malmeanum from subsp. commersonii on the bases of leaflets decreasing gradually toward the base, narrowly decurrent to petiolulate leaflets, low to median articulation, and corolla always white. Correll (1962) treated these taxa as forms and considered f. malmeanum to be distinguished from commersonii by the presence of at least some petiolulate leaflets and often two or more interjected leaflets. Metz and Oliveira (2004) stated that some populations of S. malmeanum when grown in glasshouses did not maintain the white color of their flowers and consider these populations as possible hybrids. We have not seen this behavior in the populations we grew. Metz and Oliveira (2004) considered S. malmeanum as a form of S. commersonii, but questioned the validity of even this rank on the basis of the differences stated.

Fourteen triploid counts have been reported from various publications from Uruguay and Brazil (Hijmans et al., 2007), but vouchers have not been made or are unclear.

For Solanum nicaraguense Rydb., we list “probable isotypes” because the specimens have no collection number; the locality [“Nicaragua”] is the same and the specimens appear to belong to the type gathering. Solanum nicaraguense is the only record of a wild potato from Nicaragua. The only information we found on the collector Charles W. Flint (Anonymous, 1889) is a one-paragraph biography that provides no itineraries .As pointed out by Hawkes (1990), the type appears to be a misidentified specimen of S. commersonii Dunal, which grows in southern South America. The Flint collection could represent an established disjunct population of S. commersonii, a waif, a mislabeled collection, or possibly even a new species. Collectors should be alerted to search in Nicaragua.

References:

Anonymous 1889. Scientific news.
Amer. Nat. 23: 748-752.

Correll, D.S. 1962. The potato and its wild relatives.
Contr. Texas Res. Found., Bot. Stud. 4: 1-606.

Hawkes, J.G. & J.P. Hjerting 1969. The potatoes of Argentina, Brazil, Paraguay and Uruguay: a biosystematic study.
Oxford Univ. Press, Oxford, UK.

Hawkes, J.G. 1990. The potato: evolution, biodiversity and genetic resources.
Oxford: Belhaven Press.

Mentz, L.A. & P.L. de Oliveira 2004. Solanum (Solanaceae) na região sul do Brasil.
Pesquisas, Bot. 54: 1-327.

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.

Hijmans, R., T. Gavrilenko, S. Stephenson, J. Bamberg, A. Salas & D.M. Spooner 2007. Geographic and environmental range expansion through polyploidy in wild potatoes (Solanum section Petota).
Global Ecol. Biogeogr. 16: 485-495.

Taxonomic name:

Solanum commersonii (Solanaceae)

Solanaceae Source

A global taxonomic resource for the nightshade family

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Solanum commersonii

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