2n = 6x = 72 voucher: Castillo et al. 1243 (PTIS) (Hijmans, et al. 2007)
2n = 4x = 48 voucher: Castillo et al. 1212 (PTIS) (Hijmans, et al. 2007)
Solanum colombianum occurs in northern South America from western Venezuela (Distrito Federal) to northern Peru (Dept. Cajamarca), in moist habitats, often in rich organic soils, in sunny openings in woods or at forest edges, or in páramo among shrubs, often in disturbed habitats such as streamsides or roadsides or landslides, or in recently burned woods or forest clearings where populations can be extensive; 1800-3950 m in elevation. Plants previously identified as S. colombianum from Panama are now recognized as S. woodsonii.
Solanum colombianum is a member of Solanum sect. Petota Dumort., the tuber-bearing cultivated and wild potatoes. Within sect. Petota, Solanum colombianum is a member of a distinctive group of species formerly classified in series Conicibaccata (see below). 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).
Hawkes (1990) treated Solanum colombianum as one of 40 species in Solanum sect. Petota series Conicibaccata Bitter, a group containing diploids (2n = 24), tetraploids (2n = 48), and hexaploids (2n = 72). The polyploids are mainly distributed from southern Mexico south to central Peru (one species in northern Bolivia), and the diploids from northern Peru to central Bolivia.
The species boundaries and relationships of members of series Conicibaccata have been studied using plastid DNA restriction sites (Castillo and Spooner, 1997), morphology (Castillo and Spooner, 1997; Fajardo et al., 2008), AFLPs (Jiménez et al., 2008), nuclear DNA (“waxy”) sequence data (Spooner et al., 2008), other nuclear DNA sequence data (Fajardo & Spooner 2011), and monographic studies (Hawkes, 1990; Hawkes and Hjerting, 1989; Ochoa, 1990, 1999). The plastid DNA restriction site and morphological data divide the diploids and polyploids into two clades or phenetic groups, respectively, but the morphological separation generally depends on the use of character states that sometimes overlap in range. The DNA sequence data show the polyploids to be of allopolyploid origin from the diploid members of the series and members of species outside of the series.
A monographic study in progress by Fajardo and Spooner, using the above data, and herbarium specimens, is recognizing only 17 species. All are very similar, united as a group by conical fruits, leaves with generally parallel sided morphology, and narrowly ovate to elliptical leaflets. However, some unrelated species also have conical fruits, such as the Mexican diploid species S. hintonii Correll, S. lesteri Hawkes and Hjert. and S. trifidum Correll; the Mexican hexaploid species S. iopetalum (Bitter) Hawkes; and the Bolivian species S. circaeifolium Bitter. An additional problem is that some species possess ovoid fruits that are not absolutely distinct from the conical fruits of the above species or the globose fruits more common in the majority of the members of sect. Petota.
Solanum colombianum is by far the most widely distributed and polymorphic polyploid member of the series, composed of both tetraploid cytotypes (such as the previous name S. colombianum and others), and the hexaploid cytotypes S. moscapanum, S. sucubunense and S. tundalomense. Relative to the other South American polyploids, S. colombianum may be a plesiospecies (sensu Rieseberg and Brouillet, 1994; Olmstead, 1995), with the other sympatric polyploids (S. flahaultii Bitter, S. garcia-barrigae Ochoa, and S. lobbianum Bitter) as phenetically distinctive local derivatives. Its polymorphism and possible plesiomorphic species status make it hard to define, and is best differentiated from other polyploids by lack of characters that define them. These include, for example, the lack of a seed spot found in S. longiconicum, lack of an enlarged or differently shaped terminal leaflet in comparison to lateral leaflets as in S. garcia-barrigae or S. pillahuatense, lack of densely pubescent leaves as in S. lobbianum.
Dunal (1852) described S. otites based on Linden 426 in the Boissier Herbarium at G. There are two specimens of Linden 426 at G but only one bears Dunal’s handwriting that we consider as holotype. Both of these specimens have three pairs of lateral leaflets (3-jugate) We consider duplicates of this collection at BR, FI, G, OXF and P as isotypes. Bitter (1912) redescribed S. otites as a species both 2- and 3-jugate, but described two forms (forma dizygum and forma trizygum) differing in this character. A sheet at W bears two specimens differing in 2- vs. 3-jugate leaves with his handwriting describing this variation that we consider as type material.
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.
Castillo-T., R., & D.M. Spooner 1997. Phylogenetic relationships of wild potatoes, Solanum series Conicibaccata (sect. Petota). Syst. Bot. 22: 45-83.
Fajardo, D., R. Castillo, A. Salas, & D.M. Spooner 2008. A morphometric study of species boundaries of the wild potato Solanum series Conicibaccata: a replicated field trial in Andean Peru. Syst. Bot. 33: 183-192.
Fajardo, D. & D.M. Spooner. 2011. Phylogenetic relationships of Solanum series Conicibaccata and related species in Solanum section Petota inferred from five conserved ortholog sequences. Syst. Bot. 36:163-170.
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Hawkes, J.G. 1990. The potato: evolution, biodiversity and genetic resources. Oxford: Belhaven Press.
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.
Jiménez, J.P., A. Brenes, A. Salas, D. Fajardo & D.M. Spooner 2008. The use and limits of AFLP data in the taxonomy of polyploid wild potato species in Solanum series Conicibaccata. Conserv. Genet. 9: 381-387.
Ochoa, C.M. 1999. Las papas de sudamerica: Peru (Parte I). Lima, Peru: International Potato Center.
Olmstead, R.G. 1995. Species concepts and plesiomorphic species. Syst. Bot. 20: 623-630.
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Spooner, D.M., F. Rodríguez, Z. Polgár, H.E. Ballard Jr. & S.H. Jansky 2008. Genomic origins of potato polyploids: GBSSI gene sequencing data. The Plant Genome, a suppl. to Crop Sci. 48 (S1): S27–S36.