Solanum schenckii

Citation author:

Bitter

Citation:

Repert. Spec. Nov. Regni Veg. 11: 448. 1912.

Type:

Mexico. Puebla [stated as Veracruz]: Boca del Monte near Esperanza, 2 Sep 1908, Schenck 126 (B, destroyed). Neotype: cultivated (place of cultivation unknown) from MEXICO. Puebla: Esperanza, going 9 km SE, about 2-3 km past Boca del Monte station on rd to Cumbre de Aguila (microwave station), J. P. Hjerting & J. Gómez 290 (neotype designated by Hawkes 1990: 196: K!; isoneotypes: BM!, C[2]!, G!, GH!, K[2]!, PTIS!, WIS!).

Last edited by:

Spooner, D.M.

Written by:

Spooner, D.M.

Habit:

Herbaceous tuber-bearing perennials up to 0.45 m tall. Stems 3-5 mm in diameter at base of plant.

Sympodial structure:

Sympodial units typically 3-6-foliate.

Leaves:

Pseudostipules 5-11 mm long, lunate. Leaves odd-pinnate, 9-21 cm long, 5-9 cm wide, strigose, puberulent, or pubescent adaxially and abaxially; petioles 1-4 cm long; lateral leaflet pairs 2-4, frequently the size of the lateral leaflets rapidly diminishing toward the vbase of the leaf, most distal lateral leaflets 3.5-6 cm long, 1.8-2.6 cm wide, ovate to elliptical to obovate, apex acute to acuminate, base oblique, cuneate, typically sessile, highly decurrent on the rachis, rarely petiolulate, petiolules up to 1.5 mm long; terminal leaflet 3.7-8.4 cm long, 1.6-5.5 cm wide, wide elliptical to obovate, apex acute, base cuneate; generally without interjected leaflets, rarely 1 or 2.

Inflorescences:

Inflorescence a dichasially branched, ebracteate, monochasial or dichasial cyme, 2-3 forked, generally in the distal half of the plant, with 4-7 flowers, all flowers perfect, peduncle 1-4.5 cm long; pedicels 13-30 mm long, articulate between the proximal ¼ and the distal ¼.

Flowers:

Flowers with the calyx 5-12 mm long, lobes often noticeably wide, acumens 0.5 mm long. Corollas 2-3.3 cm in diameter, pentagonal to rotate, acumens 1-3 mm long, edges of corolla flat, not folded dorsally, typically light violet or violet-blue adaxially, and darker purple violet abaxially with a narrow light margin along the edges of the abaxial side, sometimes a pattern on the abaxial side with the petals darker than the interpetalar tissue. Anthers 4-6 mm long, connate, yellow, apically poricidally dehiscent and often maturing to a short introrse apical slit, filaments 1-4 mm long. Ovary with style 8-11 mm long, exceeding stamens by 2-4 mm, straight, with stigma globose.

Fruits:

Fruits 1.8-2.5 cm long, ovoid, medium to deep green, dotted or mottled with lighter green.

Seeds:

Seeds from living specimens green-white throughout, ovoid, ca. 2 mm long, with a thick covering of “hair-like” lateral walls of the testal cells that make the seeds mucilaginous when wet. Removal of these hair-like lateral walls by enzyme digestion reveals a honeycomb pattern at their base.

Chromosome number:

2n = ploidy missing =72 voucher missing = (Spooner & Hijmans 2001)

Distribution:

Mexico (Querétaro south to Puebla and Oaxaca), (1780-) 2420-2900 (-3700) m; rich soil of oak and pine forests, fencerows, among bushes.

Phenology:

Flowering and fruiting August through October.

Phylogeny:

Solanum schenckii belongs to the potato clade of Solanum (Bohs, in press). Spooner and Sytsma (1992) placed S. schenckii and all other North and Central American members of the Iopetala group (S. guerreroense, S. hougasii, S. schenckii) in a terminal clade baed on chloroplast DNA restriction site data. Included here are four polysomic polyploid 6x(4EBN) species; this ploidy/EBN shared in North and Central America only with S. demissum. The members of the Iopetala group are very similar to each other and to one of their putative genome contributors, S. verrucosum (diploid). The members of the Iopetala group also are morphologically similar to S. stoloniferum, 4x(2ENB), but are separated from it by strong EBN-based crossability barriers. There are no clear morphological characters uniting members of this group, their parental origins are unknown and, like other polyploids, they could have multiple origins. These factors make them difficult to classify in any phylogenetic classification and frustratingly difficult to identify without well-preserved complete flowering and fruiting specimens. We define the Iopetala group largely based on the 6x(4EBN) crossability.

Commentary:

Solanum schenckii is partly distinguished by its decurrent leaflets, but this decurrence is sometimes only slight (see Fig. 46 in of Spooner et al., 2004), and other species occasionally produce decurrent leaflets as well (e.g., S. jamesii, Fig. 6 of Spooner et al., 2004). It also characteristically has calyx lobes wider than other species from North and Central America. Most specimens are much easier to identify in living condition, where they more clearly show the sharp contrast to the light violet coloration of the corolla abaxially, and very dark violet adaxially. Despite these minor and sometimes inconstant diagnostic characters, the species was well distinguished from other members of the group in the morphological phenetic study of Spooner et al. (1995).

Bitter (1912) cited Schenck 126 (B) as the holotype for S. schenckii. The type was destroyed, but a drawing of a single leaf of the type, at GOET! (Correll neg. 601: BM!, F!, GH!, K!, NY!, UC!) shows the lateral leaflet decurrency of this species. Correll (1952) and Hawkes (1963) listed S. schenckii as an excluded and dubious name, respectively. Correll (1962) included S. schenckii in S. oxycarpum. Flores Crespo (1968) rediscovered the species very near the type locality. Hawkes (1990) designated another collection near the type locality (J. P. Hjerting & J. Gómez 290) as the neotype collection. The date of gathering this collection is unknown.

References:

Bitter, G. 1912. Solana nova vel minus cognita, V, VI, IX, X, XI.
Repert. Spec. Nov. Regni Veg. 11: 349-394, 431-473, 12: 1-10, 49-90, 136-162.

Correll, D.S. 1952. Section Tuberarium of the genus Solanum of North America and Central America.
U.S.D.A. Agric. Monogr. 11: 1-243.

Hawkes, J.G. 1963. A revision of the tuber-bearing Solanums. II.
Scott. Pl. Breed. Sta. Rec. 1963: 76-181.

Flores Crespo, R. 1968. Section Tuberarium of the genus Solanum of North America and Central America.
U.S.D.A. Agric. Monogr. 11: 1-243.

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

Spooner, D.M. & K.J. Sytsma 1992. Reexamination of series relationships of Mexican and Central American wild potatoes (Solanum sect. Petota): evidence from chloroplast DNA restriction site variation.
Syst. Bot. 17:432-448.

Spooner, D.M., R.G. van den Berg, & J.B. Bamberg 1995. Examination of species boundaries of Solanum series Demissa and potentially related species in series Acaulia and series Tuberosa (sect. Petota).
Syst. Bot. 20: 295-314.

Spooner, D.M. & R.J. Hijmans 2001. Potato systematics and germplasm collecting, 1989-2000.
Amer. J. Potato Res. 78:237-268; 395.

Spooner, D.M., R.G. van den Berg, A. Rodríguez, J. Bamberg, R.J. Hijmans, & S.I. Lara-Cabrera 2004. Wild potatoes (Solanum section Petota; Solanaceae) of North and Central America.
Syst. Bot. Monog. 68: 1-209 + 9 plates.

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.

Genetics:

Chloroplast DNA restriction site data available in: Spooner and Sytsma (1992).

Taxonomic name:

Solanum schenckii (Solanaceae)

Solanaceae Source

A global taxonomic resource for the nightshade family

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Solanum schenckii

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