Solanaceae Source

A global taxonomic resource for the nightshade family

Revision of Solanum kurtzianum from Thu, 2013-12-19 16:22

Citation author: 
Bitter & Wittm.
Citation: 
Bot. Jahrb. Syst. 50, Beibl. 548. 1914.
Type: 
Argentina. La Rioja: Sierra Velasco, Yacuchi, 2100 m, F. Kurtz 15422 (holotype, B, destroyed [F neg. 2781, G, F-621210]; lectotype, CORD, designated by Hawkes and Hjerting, 1969: 408).
Last edited by: 
Spooner, D.M.
Written by: 
Spooner, D.M. & A. Clausen
Habit: 
Herbs 0.15-0.5 m tall, erect. Stems 3-4 mm in diameter at base of plant, green to purple or slightly green and purple mottled, unwinged or with wings less than 1 mm, subglabrous to sparsely covered with short whitish hairs; 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 12.5-25 x 8-13.5 cm, green, often glaucous and with the central midrib purple, membranous to chartaceous, sparsely pubescent to subglabrous adaxially and abaxially with hairs like those of the stems; lateral leaflet pairs 3-4, often subequal except for the most proximal 1-2 pairs that are greatly reduced in size; most distal lateral leaflets 3.8-8.3 x 1.5-4 cm, broadly ovate to broadly elliptic, the apex acute to acuminate, the base typically rounded and oblique; terminal leaflet 3.6-12.5 x 2.3-5 cm, broadly ovate to broadly elliptic, the apex acute to acuminate, the base truncate to cuneate; interjected leaflets 0-7, sessile to short petiolulate, ovate to orbicular, petiolules 0-5 mm; petioles 0-3.5 cm, pubescent as the stems. Pseudostipules 6-11 mm long, pubescent with hairs like those of the stem.
Inflorescences: 
Inflorescences 5-10 cm, terminal with a subtending axillary bud, generally in distal half of the plant, usually forked, with 4-25 flowers, with all flowers apparently perfect, the axes pubescent with hairs like those of the stem; peduncle 2.3-7 cm long; pedicels 10-25 mm long in flower and fruit, spaced 1-10 mm apart, articulated at or below the middle, sometimes low in the proximal half.
Flowers: 
Flowers homostylous, 5-merous. Calyx 4-7 mm long, the tube 1-2 mm, the lobes 2-6 mm, acute to apiculate, the acumens 1-3 mm long, pubescent with hairs like those of the stem. Corolla 2.5-3.3 cm in diameter, substellate to pentagonal, white to white with a violet streak in the center of the corolla lobes abaxially and adaxially, the tube 1-2 mm long, the acumens 2-5 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 5-7 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 8-11 mm x ca. 1 mm, exceeding stamens by 3-5 mm, straight, glabrous; stigma clavate to capitate.
Fruits: 
Fruit a globose berry, 1-1.5 cm in diameter, green when ripe, often with scattered white dots, 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 = 2x = 24 voucher: Clausen & Spooner 4544 (BAL) (Hijmans, et al. 2007)

Distribution: 

Solanum kurtzianum is found in western and northwestern Argentina (Provs. Mendoza, San Juan, La Rioja and Catamarca), in dry rocky hillsides, desert steppes and among herbs, spiny shrubs and low woods, along streamsides, dry river beds and alluvial cones, (750) 1400-2100 (3000) m in elevation.

Phenology: 
Flowering and fruiting from January to May.
Phylogeny: 

Solanum kurtzianum is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, Solanum kurtzianum is a member of a very diverse clade related to the cultivated potato. 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 kurtzianum can be distinguished from the very similar S. chacoense by its finely ciliate leaflets and its generally smaller size (0.15 – 0.5 m tall vs. 0.5-2 m tall in S. chacoense).

A natural hybrid between S. kurtzianum and S. chacoense was described by Brücher (1962) as S. ruiz-lealii, and this was accepted by Hawkes and Hjerting (1969) and Hawkes (1990). Brücher (1966) later argued against this hybrid origin as one of the putative parents has never been reported from the province of Mendoza. Raimondi et al. (2005) examined the hypothesis of hybridization by phenetic analyses of morphological and molecular data and cytological analyses of interspecific hybrids. They concluded that S. ruiz-lealii is not a recent natural hybrid of S. kurtzianum x S. chacoense but originated by divergence of S. chacoense or by hybridization between S. chacoense and another unnamed taxon and proposed to maintain the species status of S. ruiz-lealii. Brücher (1962) differentiated S. ruiz-lealii from S. chacoense by its very short and glabrous calyx lobes, corollas with prominent stellate shape, and triangular winged stem. Raimondi et al. (2005) confirmed the morphological differences between S. ruiz-lealii and S. chacoense, but not between S. ruiz-lealii and S. kurtzianum. On the basis of their molecular study, S. ruiz-lealii appears as a separate entity but more related to S. chacoense than to S. kurtzianum. On the basis of our analysis of herbarium data, many populations of S. kurtzianum have white flowers, are subglabrous, and have fruits that are green or green with white dots. The characters of S. ruiz-lealii fall within the range of variation of S. kurtzianum and we consider them to be conspecific.

We observed specimens collected at the type locality of S. ruiz-lealii in Mendoza, from Punta de Agua, and from Aguanda (in the same province). These specimens have the leaf characters of S. kurtzianum, including the ciliate margins. It is frequently difficult to distinguish S. chacoense from S. kurtzianum, but based upon the comparisons of germplasm specimens in a common garden and of herbarium specimens, and due to the fact that S. chacoense does not occur in Mendoza Province, we consider that the specimens both from Punta de Agua and Aguanda are S. kurtzianum.

References: 

Brücher, H.E. 1962. Nuevas especies de Solanum (Tuberarium) de la zona semiárida del NW Argentino.
Rev. Fact. Univ. Cuyo 9: 7–14.

Brücher, H.E. 1966. Solanum ruiz-lealii Brücher, a wild endemic potato of the Province of Mendoza, in danger of extinction.
Multequina 5: 83–90.

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.

Raimondi, J.P., I.E. Peralta, R.W. Masuelli, S. Feingold & E.L. Camadro. 2005. Examination of the hybrid origin of the wild potato Solanum ruiz-lealii Brücher.
Pl. Syst. Evol. 253: 33–51.

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 kurtzianum (Solanaceae)
Wed, 2013-11-20 11:00 -- sandy
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