Solanaceae Source

A global taxonomic resource for the nightshade family

Revision of Solanum hypacrarthrum from Thu, 2013-12-19 16:20

Citation author: 
Repert. Spec. Nov. Regni Veg. 11: 367. 1912.
Peru. Lima: Prov. Canta, slopes of Puruchuco, Apr 1832, Matthews 772 (holotype, BREM [Correll neg. 794, BM000881709, F-1603087, LL, MO-5594704, NY, PTIS, UC1152296]; isotypes, CGE [Correll neg. 769, BM000881710, F-1603112, LL, NY, UC1152296], E-160289, E-129554 [Correll neg. 242, BM000881713, F-1604003, LL, NY, UC1152297], K [Correll neg. 244, BM000881711, F-1604005, LL, MO-5594706, NY-2 sheets, PTIS, UC1152296], L-62993, OXF-57361 [Correll neg. 243, BM000881712, F-1604004, LL, NY, UC1152297], US [Correll neg. 241, BM000881714, UC1152297]).
Last edited by: 
Spooner, D.M.
Written by: 
Spooner, D.M. & M. Ames
Herbs 0.3-0.7 m tall, erect. Stems 1-8 mm in diameter at base of plant, green or green mottled with purple, usually unwinged but sometimes with a narrow wing to 1 mm, glabrous; tubers typically moniliform (multiple tubers arranged along the stolon like beads on a necklace).
Sympodial structure: 
Sympodial units tri- to plurifoliate, not geminate.
Leaves simple or odd-pinnate, the blades 6.6-21.1 x 3.1-12 cm, dark green abaxially and light green adaxially, coriaceous, glabrescent adaxially with scarce short white hairs, usually glabrous abaxially; lateral leaflet pairs 0-3, decreasing in size toward the leaf base when present, with the terminal leaflet considerably larger than the most distal pair of laterals; most distal lateral leaflets 0.6-5.8 x 0.3-3.3 cm, ovate to elliptic, the apex acute to acuminate, the base typically sessile and narrowly decurrent onto the rachis; terminal leaflet 4.8-18 x 3.1-10.4 cm, usually broadly ovate, the apex acute to acuminate, the base usually attenuate; interjected leaflets 0-4, sessile, ovate to orbicular; petioles 0-3.2 cm, glabrous to glabrescent with short white hairs. Pseudostipules, when present 3-10 mm long, glabrous to subglabrous.
Inflorescences 2.8-18 cm, terminal with a subtending axillary bud, generally in distal half of the plant, usually forked, with 8-34 flowers, with all flowers apparently perfect, the axes usually glabrous to glabrescent with scarce short white hairs; peduncle 1.8-10.7 cm long; pedicels 13-41 mm long in flower and fruit, spaced 3-5 mm apart, articulated very high in the distal half.
Flowers homostylous, 5-merous. Calyx 8-10 mm long, the tube 3-7 mm, the lobes 2-4 mm, ovate, with linear acumens 3-5 mm long, usually glabrous to glabrescent with scarce short white hairs. Corolla 2.8-4.9 cm in diameter, rotate, white, the tube 1-2 mm long, the acumens 1-3 mm long, the corolla edges flat, not folded dorsally, glabrous abaxially and adaxially. Stamens with the filaments 1-2 mm long; anthers 4-8 mm long, lanceolate, connivent, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 3-10 mm x ca. 1 mm, exceeding stamens by 2-5 mm, straight, glabrous; stigma clavate to capitate.
Fruit an ovoid to pyriform berry, 0.8-1.6 cm wide, 0.8-1.7 cm long, light to medium green, sometimes with white spots when ripe, glabrous.
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: Ochoa & Salas 14727 (CIP) (Hijmans, et al. 2007)


Central to northern Peru (Depts. Ancash, Cajamarca and Lima), on rocky hills, among bushes and other herbaceous vegetation, 1800-3800 m in elevation.

Flowering and fruiting from March to June.

Solanum hypacrarthrum is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, Solanum hypacrarthrum is a member of a distinctive clade of southern Ecuadorian and Peruvian species formerly classified in series Piurana and some other series that frequently possess moniliform tubers and shiny coriaceous leaves. 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).


Solanum hypacrarthrum is very similar to S. simplicissimum. Both species have white corollas and coriaceous, simple to odd-pinnate leaves with a broadly ovate terminal leaflet much larger than the laterals. Our morphological examination of germplasm collections of these species grown in a greenhouse initially led us to consider them to be conspecific, but nuclear DNA sequence data (Ames, 2008) showed them to be members of distinct clades. This forced us to look for characters to separate them and we found only a red coloration the midvein in the terminal leaflet of S. simplicissimum that differs from S. hypacrarthrum, which has green midveins.

This is the first treatment to consider S. guzmanguense as conspecific with S. hypacrarthrum. Ochoa (1999) placed S. guzmanguense in series Simplicissima (with S. simplicissimum) and S. hypacrarthrum in series Piurana, but nuclear DNA sequence data (Ames, 2008) show them to be members of the same clade. Ochoa (1999) distinguished S. guzmanguense by its “conspicuously winged stem, very robust habit, and large simple leaves.” His maps showed a gap in distribution between S. guzmanguense and S. hypacrarthrum, with none of the latter in Cajamarca Department. We found the more typical smaller morphotypes of S. hypacrarthrum in Cajamarca Department and consider S. guzmanguense simply as a large plant of S. hypacrarthrum.


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.

Ames, M. 2008. Evolutionary relationships of Solanum series Piurana and related species in Solanum section Petota (wild potatoes).
Ph.D. dissertation. Madison, WI: University of Wisconsin-Madison.

Wed, 2013-11-20 11:00 -- sandy
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith