Solanaceae Source

A global taxonomic resource for the nightshade family

Solanum hjertingii

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Citation author: 
J. G. Hawkes
Citation: 
A revision of the tuber-bearing Solanums, 2nd ed: 123, 171. 1963.
Type: 
Mexico. Coahuila: near Saltillo, Lirios, fields south of village on lower border of mountain forests, growing as weed of cultivation, 2300 m, 23 Aug 1858, J. G. Hawkes, J. P. Hjerting, & R. N. Lester 1356 (lectotype, designated by Spooner et al., 2004: K, lowermost of three specimens on a sheet labeled “sheet 1”!; isolectotypes, C!, K!, US-3314897!).
Last edited by: 
Spooner, D.M.
Written by: 
Spooner, D.M.
Habit: 
Herbaceous tuber-bearing perennials 0.2-0.4 m tall. Stems 3-6 mm in diameter at base of plant.
Sympodial structure: 
Sympodial units typically 3-6-foliate.
Leaves: 
Pseudostipules 4-14 mm long, lunate. Leaves odd-pinnate, 10.5-21 cm long, 5-12 cm wide, glabrous or glabrescent and with scattered hairs, especially on veins, adaxially and abaxially; petioles 1.5-3 cm long; lateral leaflet pairs 2-4, the size of the lateral leaflets gradually diminishing gradually towards the base of the leaf; most distal lateral leaflets 2-4 cm long, 0.9-2.3 cm wide, ovate to narrowly to broadly elliptical, apex acute to acuminate, base oblique, cuneate to cordate, petiolules 7-7 mm long; terminal leaflet 2.5-4 cm long, 1-2.5 cm wide, narrowly to broadly elliptical to obovate, apex acute to acuminate, base cuneate to cordate; interjected leaflets 2-19.
Inflorescences: 
Inflorescence a dichasially branched, ebracteate, monochasial or dichasial cyme, 2-3 forked, generally in the distal half of the plant, with 6-18 flowers, all flowers perfect, peduncle 2.5-12 cm long; pedicels 6-28 mm long, articulate between the proximal ¼ and the distal ¼.
Flowers: 
Flowers with the calyx 10-27 mm long, lobes acute to long-attenuate, acumens 1-4 mm long. Corollas 2.7-3.6 cm in diameter, pentagonal to rotate, acumens 1.5-4 mm, edges of corolla flat, not folded dorsally, light violet adaxially, darker violet abaxially. Anthers 2.5-7.5 mm long, connate, yellow, apically poricidally dehiscent and often maturing to a short introrse apical slit, filaments 1-4 mm long. Ovary with style 10-11 mm long, exceeding stamens by 2-8 mm, straight, with stigma globose.
Fruits: 
Fruits 0.8-1.2 cm in diameter, globose to slightly ovoid, greenish white to medium green with white spots to medium green or medium green throughout.
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 =48 voucher missing = (Spooner & Hijmans 2001)

Distribution: 

Mexico: northeastern Mexico, states of Coahuila, Nuevo León, San Luis Potosí, Tamaulipas, (1230) 1650-3210 m; growing in and at borders of cultivated fields, in pine, oak, juniper, or Opuntia forests, bushy hillsides, grasslands, fencerows.

Phenology: 
Flowering and fruiting July through October.
Phylogeny: 

Solanum hjertingii belongs to the potato clade of Solanum (Bohs, in press). Spooner and Sytsma (1992) placed S. hjertingii in the most derived clade of section Petota based on chloroplast DNA restriction site data. Spooner et al. (2004) erected the Longipedicellata group for S. hjertingii and S. stoloniferum. These two species are polysomic polyploids and 4x(2EBN). There are no clear group-specific morphological characters defining the Longipedicellata group (see discussion in Spooner et al. 2004).

Commentary: 

Solanum hjertingii is most similar to S. stoloniferum but is distinguished by its curved styles generally long-exserted (2-8 mm) beyond the tip of the anther tube and glabrous to glabrescent leaves (Spooner et al. 2001). Solanum stoloniferum has straight styles exserted 2-4.5 mm beyond the tip of the anther tube, and strigose, puberulent, or pubescent leaves.

Hawkes (1990) placed six species in ser. Longipedicellata: S. fendleri, S. hjertingii, S. matehualae, S. papita, S. polytrichon, and S. stoloniferum. The specimens Hawkes labeled as these names are all tetraploid (2n = 4x = 48) and grow in the southeastern United States (Hawkes’s S. fendleri) and Mexico. Morphological data (Spooner et al. 2001) supported at best only three species in series Longipedicellata: 1) S. polytrichon, 2) S. hjertingii (including S. matehualae), and 3) S. stoloniferum (including S. fendleri and S. papita). Solanum polytrichon was supported as a species only by a canonical variate analysis, but not by a principal components analysis that intermixed S. polytrichon with many other species, and thus was the least supported species.

Hawkes (1963) designated a specimen at K of Hawkes et al. 1356 as the “type” of S. hjertingii. There are two sheets at K labeled “sheet 1” and “sheet 2,” both labeled as isotypes on labels typed by Hawkes. Sheet 1 has three separate specimens, and Spooner et al. (2004) chose the lowermost as lectotype.

Hjerting and Tarn suggested in the description of S. matehualae (Phytologia 65: 116. 1988) that S. hjertingii was very similar to S. matehualae. Spooner et al. (2001) showed these two species to cluster by morphological data, and Van den Berg et al. (2002) to cluster by RAPD and AFLP data. The only morphological character Spooner et al. (2004) could find to distinguish the two elements is a slight difference in corolla color, with S. matehualae darker purple than S. hjertingii.

References: 

Dunal, M.F. 1814. Morelle, Solanum.
In Encyclopédie Méthodique, Botanique, Suppl. 3., ed. J. L. M. Poiret, 738-780. Paris: Chez H. Agasse.

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

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.

Dean, E.A. 1997. Lectotypification and synonymy of the names of Solanum mozinianum Dunal and Solanum uniflorum Sessé & Moçiño.
Brittonia 49: 192-196.

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). AFLP, RAPD, and microsatellite data listed in: Van den Berg et al. (2002).

Taxonomic name: 
Solanum hjertingii (Solanaceae)
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