Solanum raphanifolium

Citation author:

Cárdenas & Hawkes

Citation:

J. Linn. Soc. London 53: 94. 1946.

Type:

Peru. Cuzco: near Cuzco, Sacsahuaman, Mar 1943, M. Cárdenas & H. Gandarillas 3500 (lectotype, K000005848 [Correll neg. 131, F-1604897, LL, NY, UC1152384], designated by Hawkes, 1990: 102; isolectotype, K000440183).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M.

Habit:

Herbs 10-40 cm tall, typically erect; sometimes low-growing. Stems 3-4 mm in diameter at base of plant, green to brown to purple, unwinged, sparsely pilose; tubers typically borne singly at the end of each stolon.

Sympodial structure:

Sympodial units tri- to plurifoliate, not geminate.

Leaves:

Leaves odd-pinnate, more rarely simple, the blades 2-20 x 1.5-9 cm, dark green adaxially, gray-green abaxially, membranous to chartaceous, sparsely pilose adaxially, more densely and finely pilose abaxially; lateral leaflet pairs 0-5, gradually decreasing in size toward the leaf base, with the terminal leaflet larger than the laterals; most distal lateral leaflets 0.5-8 x 0.2-4 cm, ovate to obovate, the apex rounded to slightly pointed or apiculate, the base typically decurrent on the rachis; terminal leaflet 1.5-12 x 1-8 cm, broadly elliptic or broadly ovate to obovate, the apex broadly rounded and apiculate, the base cuneate; interjected leaflets 0-5, sessile to short petiolulate, ovate to orbicular, petioles 0.5-6 cm, pubescent as the stems. Pseudostipules 5-7 mm long, pubescent with hairs like those of the stem.

Inflorescences:

Inflorescences 4-15 cm, terminal with a subtending axillary bud, generally in the distal half of the plant, usually forked, with 1-12 flowers, with all flowers apparently perfect, the axes sparsely pubescent with hairs like those of the stem; peduncle 2.5-14 cm long, sparsely pilose and somewhat glandular; pedicels 15-35 mm long in flower and fruit, spaced 1-10 mm apart, articulated very high in the distal half at 5-8 mm below base of calyx.

Flowers:

Flowers homostylous, 5-merous. Calyx 6-7 mm long, the tube 1-2 mm, the lobes 1-4 mm, ovate to ovate-lanceolate, abruptly narrowed to the apex, the acumens 1-1.5 mm long, sparsely pilose with hairs like those of the stem. Corolla 2.5-3.5 cm in diameter, pentagonal to rotate-pentagonal, violet to deep purple adaxially and abaxially, the tube 1-2 mm long, the acumens 3-6 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 5-6 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 7.5-9 mm x ca. 1 mm, exceeding stamens by 2-3 mm, straight, glabrous to sparsely papillose; stigma capitate.

Fruits:

Fruit a globose to subovoid berry, 1.5-2 cm wide, 1.6-2.2 cm long, light green, sometimes scattered 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 7208 (CIP, MOL, PTIS, WAG) (Hijmans, et al. 2007)

Distribution:

Solanum raphanifolium occurs in southern Peru (Depts. Cuzco, Apurímac, Puno) in a wide variety of habitats, often as a weed in cultivated fields, at the edge of forests, along roadsides, in rock piles or near stone walls, on eroded slopes, in rocky areas, among herbs and mosses, frequently among Stipa ichu, Schinus molle, puya, scrub, cacti, and trees, in full sun to deep shade, often in disturbed soil, also in rich humus or poor gravelly clay, in wet or dry soil; (2000) 2700-4500 m in elevation.

Phenology:

Flowering and fruiting collections made mainly from January to April.

Phylogeny:

Solanum raphanifolium is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, Solanum raphanifolium 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 raphanifolium was hypothesized by Ugent (1970) to be a recent stabilized diploid hybrid species between S. canasense Hawkes and S. boliviense Dunal (as S. megistacrolobum Bitter). His hypothesis was based on intermediate morphology and inference from overlapping distributional data. Spooner et al. (1991) discounted this hypothesis because of multiple plastid DNA synapomorphies in S. raphanifolium not possessed by either putative parental species.

Solanum raphanifolium is difficult to distinguish from S. boliviense Dunal and S. sogarandinum Ochoa based on morphological data, although in addition to the plastid DNA data separating it from S. boliviense, it is distinguished by single-to low-copy nuclear restriction site data (Giannattasio and Spooner, 1994). Solanum raphanifolium (typically erect) is distinguished from S. boliviense and S. sogarandinum (typically rosette-forming) by its habit. It overlaps in part of its range with S. boliviense in southern Peru, but is distinct from S. sogarandinum which is distributed farther north in north and central Peru (to Dept. Lima).

References:

Ugent, D. 1970. Solanum raphanifolium, a Peruvian wild potato species of hybrid origin.
Bot. Gaz. (Crawfordsville) 131: 225-233.

Spooner, D.M., K.J. Sytsma & J.F. Smith 1991. A molecular reexamination of diploid hybrid speciation of Solanum raphanifolium.
Evolution 45: 757-764.

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.

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 raphanifolium (Solanaceae)

Solanaceae Source

A global taxonomic resource for the nightshade family

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Solanum raphanifolium

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