Solanum lignicaule

Citation author:

Vargas

Citation:

Revista Argent. Agron. 10: 398. 1943.

Type:

Peru. Cuzco: Prov. Paruro, Dist. Colcha, left bank of Río Apurímac, 2750 [2800–3100] m, 7 Jan 1939, C. Vargas 1539 [Goodspeed Expedition No. 9730] (holotype, CUZ; isotypes, G [Correll neg. 741, BM000881691, F-1603865, LL, UC1152320], K000440798 [Correll neg. 922, BM000881692, F-1602997, LL, MO-5588706, UC1152320], K [Correll neg. 743, BM000881694, LL, MO-5588707, UC1152467], UC-649048 [Correll neg. 742, BM000881695, F-1603864, LL, UC1152320]).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M.

Habit:

Herbs 30-60 cm tall, erect to erect-ascending. Stems 4-7 mm in diameter at base of plant, atypically woody (for sect. Petota), yellow to brown, unwinged, densely glandular-puberulent to glandular-pilose; tubers typically orne singly at the end of each stolon.

Sympodial structure:

Sympodial units tri- to plurifoliate, not geminate.

Leaves:

Leaves odd-pinnate, the blades 7-17 x 4-14 cm, yellow-green adaxially, gray-green to whitish-gray abaxially, densely glabrescent and glandular-puberulent adaxially, densely short canescent and glandular-puberulent abaxially; lateral leaflet pairs 2-4, subequal to gradually or sometimes greatly decreasing in size toward the leaf base, with the terminal leaflet slightly larger than the most distal pair of laterals; most distal lateral leaflets 2.7-4.2 x 0.8-1.2 cm, narrowly elliptic-lanceolate to lanceolate, the apex subobtuse or pointed to attenuate-acuminate, the base cuneate to rounded, sessile to short petiolulate with petiolules 0-3 mm, sometimes decurrent on the rachis, especially in the most distal pair; terminal leaflet 5-8.5 x 1-2.5 cm, narrowly elliptic-lanceolate to lanceolate, the apex subobtuse or pointed to attenuate-acuminate, the base cuneate to rounded, sessile to short petiolulate with petiolules 0.5-0.8 cm; interjected leaflets 0-8, sessile to short petiolulate, ovate to orbicular; petioles 0.8-1.5 cm, pubescent as the stems. Pseudostipules 6-12 mm long, pubescent with hairs like those of the stem.

Inflorescences:

Inflorescences 5-10 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 densely pubescent with hairs like those of the stem; peduncle 2-5 cm long; pedicels 10-20 mm long in flower and fruit, spaced 1-10 mm apart, articulated at or slightly above the middle.

Flowers:

Flowers homostylous, 5-merous. Calyx 7-9 mm long, the tube 1-2 mm, the lobes 5-8 mm, broadly subquadrate, abruptly narrowed to long-spatulate, the acumens 4-5 mm long, densely pubescent with hairs like those of the stem. Corolla 2.5-3 cm in diameter, substellate to pentagonal, yellowish-white abaxially and adaxially, sometimes with light purple acumens and upper petal lobes, 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 1-2 mm long; anthers 4.5-6.5 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 8-9 mm x ca. 1 mm, exceeding stamens by 2-4 mm, straight, glabrous; stigma claviform.

Fruits:

Fruit an ovoid berry, ca. 1.5 cm long, ca. 1.3 cm wide, dark green flecked with small 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: Spooner & Clausen 7224 (CIP, MOL, PTIS, WAG) (Hijmans, et al. 2007)

Distribution:

Solanum lignicaule is endemic to Peru (Dept. Cuzco), among bushes or cacti, among loose stones, on rocky slopes, often in dry environments, in sandy or rocky soil; 2510-3460 m in elevation.

Phenology:

Flowering and fruiting from January to April.

Phylogeny:

Solanum lignicaule is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, S. lignicaule is a member of a very diverse clade related to the cultivated potato. Hawkes (1990) and Ochoa (1999) place S. lignicaule as the sole representative of series Lignicaulia, but its distinctive series status is not supported by plastid DNA restriction site data (Spooner and Castillo, 1997) or AFLP data (Jacobs et al., 2008). On a higher taxonomic level, S. lignicaule 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 lignicaule is one of the most distinctive species in sect. Petota, with its combination of white corollas, relatively narrow terminal and lateral leaflets, and leaves that are densely short canescent beneath. The woody habit mentioned for this species is not clearly distinctive as some other species also are firm at the base and may also be woody. There is no comparative study of members of sect. Petota quantifying woody vs. herbaceous stems.

References:

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

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.

Jacobs, M.J., R.G. van den Berg, V.G.A.A. Vleeshouwers, M. Visser, R. Mank, M. Sengers, R. Hoekstra & B. Vosman 2008. AFLP analysis reveals lack of phylogenetic structure within Solanum section Petota.
BMC Evol. Biol. 8, 145: 2-12.

Taxonomic name:

Solanum lignicaule (Solanaceae)

Solanaceae Source

A global taxonomic resource for the nightshade family

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Solanum lignicaule

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