Solanum sogarandinum

Citation author:

Ochoa

Citation:

Agronomía (Lima) 19(79–80): 168, fig. 3–5. 1954.

Type:

Peru. La Libertad: Prov. Santiago de Chuco, Sogaranda, 8 km from Santiago de Chuco, 3550 m, 12 May 1952, C. Ochoa 1440 (holotype, CUZ; isotype, US00288880 [Correll neg. 127, C, F-1604901, LL, MO-5600047, NY, UC1152435]).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M.

Habit:

Herbs 15-40 cm tall, generally rosette-forming to subrosette-forming, or erect-decumbent. Stems 2-3 mm in diameter at base of plant, green to purple or slightly green and purple mottled, unwinged, sparsely pilose with white multicellular hairs; tubers typically borne singly at the end of each stolon.

Sympodial structure:

Sympodial units tri- to plurifoliate, not geminate.

Leaves:

Leaves simple to odd-pinnate, the blades 5.5-21 x 2.5-8.5 cm, green, membranous to chartaceous, sparsely pilose adaxially, somewhat less pilose abaxially with hairs like those of the stems; lateral leaflet pairs 0-4, gradually decreasing in size toward the leaf base, with the terminal leaflet larger than the laterals; most distal lateral leaflets 1-5.5 x 0.5-3 cm, ovate to ovate-elliptic, the apex obtuse, the base conspicuously decurrent about the rachis; terminal leaflet 4-12 x 2.5-5.5 cm, broadly elliptic to ovate-elliptic, the apex broadly attenuate to obtuse or slightly pointed, the base cuneate and narrowly decurrent about the petiolule; interjected leaflets absent, petiolules absent, and when the plant has lateral leaflets the tissue decurrent on the stem; petioles 1-3 cm, pubescent as the stems. Pseudostipules absent to extremely small, 0-3 mm long, sparsely pilose with hairs like those of the stem.

Inflorescences:

Inflorescences 3-10 cm, terminal with a subtending axillary bud, generally in the distal half of the plant, usually forked, with 4-10 flowers, with all flowers apparently perfect, the axes sparsely pilose with hairs like those of the stem; peduncle 1-6 cm long, pilose; pedicels 1.5-4 mm long in flower and fruit, spaced 1-10 mm apart, articulated very high in the distal half at 5-7 mm below base of calyx.

Flowers:

Flowers homostylous, 5-merous. Calyx 6-7 mm long, the tube 1-2 mm, the lobes 5-6 mm, ovate-lanceolate, very shortly acuminate, the acumens 1-2 mm long, sparsely pilose with hairs like those of the stem. Corolla ca. 3 cm in diameter, rotate, blue to pale blue-purple adaxially and abaxially, the tube 1-2 mm long, the acumens 1-3 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 ca. 1 mm long; anthers 4.5-4.8 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style ca. 8 mm x ca. 1 mm, exceeding stamens by ca. 2.5 mm, straight, glabrous; stigma subellipsoid.

Fruits:

Fruit a globose berry, ca. 1.5 cm in diameter, light green, sometimes with light brown streaks, 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: Salas et al. 7332 (CIP, MOL, PTIS) (Hijmans, et al. 2007)

Distribution:

Solanum sogarandinum is known from northern Peru (Dept. Cajamarca), south to central Peru (Dept. Lima), growing in grasslands, jalca formations, brush fields, or altiplano, often with Stipa ichu (Ruiz & Pav.) Kunth, among rocks, in clay or sandy soil; 2800-4100 m in elevation.

Phenology:

Flowering collections made from January to March.

Phylogeny:

Solanum sogarandinum is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, the relationships are unclear. Based on plastid DNA restriction site data (Spooner and Castillo, 1997), S. sogarandinum is a member of a distinctive clade of southern Ecuadorian and Peruvian species that frequently possess moniliform tubers and shiny coriaceous leaves. However, S. sogarandinum does not possess these morphological characters, and it is morphologically similar to S. boliviense and S. raphanifolium that are members of a clade related to the cultivated potato. On a higher taxonomic level, S. sogarandinum 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 sogarandinum is difficult to distinguish from S. boliviense Dunal and S. raphanifolium Cárdenas and Hawkes, two species classified by Hawkes (1990) and Ochoa (1999) in series Megistacroloba Cárdenas and Hawkes. Solanum sogarandinum is distinguished from both of the above by plastid DNA (see phylogeny, above) and single-copy nuclear DNA (Giannattasio and Spooner, 1994b). The species has been shown to be distinguished with difficulty from S. boliviense with morphological phenetics (Giannattasio and Spooner, 1994a), but only by characters that overlap in range.

Despite the above experimental studies, it is very difficult to differentiate S. sogarandinum from S. boliviense morphologically, especially on herbarium sheets that often lack clear indications of habit and corolla shape. Solanum sogarandinum is distinguished from S. raphanifolium by its low rosette habit and from S. boliviense by its rotate corolla. In addition, it has a distinctive non-overlapping range from both of the above species, with a distribution from northern to central Peru (Lima Department), whereas the other two are distributed from Huancavelica Department southward.

References:

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

Giannattasio, R. & D.M. Spooner 1994. A reexamination of species boundaries and hypotheses hybridization concerning Solanum megistacrolobum and S. toralapanum (Solanum sect. Petota, series Megistacroloba): molecular data.
Syst. Bot. 19:106-115.

Spooner, D.M. & R. Castillo-T 1997. Reexamination of series relationships of South American wild potatoes (Solanaceae: Solanum sect. Petota): evidence from chloroplast DNA restriction site variation.
Amer. J. Bot. 84: 671-685.

Ochoa, C.M. 1999. Las papas de sudamerica: Peru (Parte I).
Lima, Peru: International Potato Center.

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 sogarandinum (Solanaceae)

Solanaceae Source

A global taxonomic resource for the nightshade family

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Solanum sogarandinum

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