Solanum luteoalbum
Andean slopes from southern Ecuador to southern Peru; gravelly or rocky slopes and cliffs to moist river valleys; 2200-3300 m.
Solanum luteoalbum belongs to the Cyphomandra clade of Solanum along with other species traditionally recognized in sections Pachyphylla and Cyphomandropsis (Bohs, in press a). Within the Cyphomandra clade, S. luteoalbum belongs to a well-supported clade that also includes S. confusum, S. hibernum, and S. stuckertii (Bohs, in press b).
Rottbøll, C. F. 1778. Acta literaria universitatis hafnensis 1: 287.
Willdenow, C.L. 1794. Phytographia 1: 1-15, pl. I-X.
Ruiz, H. & J.A. Pavón 1799. Flora Peruviana et Chilensis.
Madrid, Spain: Gabrielis de Sancha. (1965) Reprint. J. Cramer, Lehre, Stuttgart.
Persoon, C.H. 1805. Synopsis plantarum seu enchiridium botanicum.
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Dunal, M.F. 1852. Solanaceae.
Pp. 1-690 in A. P. DeCandolle (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 13(1). Victoris Masson, Paris, France.
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Macbride, J.F. 1962. Solanaceae.
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Pringle, G.J., & B.G. Murray 1991. Karyotype diversity and nuclear DNA variation in Cyphomandra.
Pp. 247-252 In: J.G. Hawkes, R.N. Lester, M. Nee, and N. Estrada-R. (eds.). Solanaceae III: Taxonomy, Chemistry, Evolution. Richmond, Surrey, UK: Royal Botanic Gardens, Kew and Linnean Society of London.
Bohs, L. 2001. Revision of Solanum section Cyphomandropsis (Solanaceae).
Syst. Bot. Monog. 61: 1-85.
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.
Bohs, L. 2007. Phylogeny of the Cyphomandra clade of the genus Solanum (Solanaceae) based on ITS sequence data.
Taxon 56: 1012-1026.
chloroplast ndhF sequence: GenBank U72749 (voucher: Bohs 2337, UT). (http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=1644491) chloroplast trnT-F sequence: GenBank AY266257 (voucher: Bohs 2337, UT). (http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=33355758) nuclear ITS sequence: GenBank AF244715 (voucher: Bohs 2337, UT). (http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=7533135)
Solanum luteoalbum is similar to S. stuckertii and S. hibernum, all of which have elliptic leaves, stellate corollas, orange globose fruits, and large angled seeds. Solanum luteoalbum can be distinguished from S. stuckertii by its purple rather than white corollas and more northerly distribution. Hairs of S. stuckertii are exclusively unbranched, whereas those of S. luteoalbum can be either unbranched or dendritically branched. Solanum luteoalbum and S. hibernum are very similar morphologically. Both species have purple corollas and are often covered with dendritically branched trichomes; in S. hibernum the leaf surfaces are strongly discolorous due to the dense whitish covering of dendritically branched hairs on the lower surface, whereas the pubescence of S. luteoalbum is more or less evenly distributed.
Solanum luteoalbum is also similar to pubescent forms of S. confusum, but can be distinguished from the latter by its stellate and usually deep purple corollas, shorter and often branched trichomes, and its more northerly geographical range.
Peruvian specimens of S. luteoalbum from the Departments of Apurimac and Cuzco have an obvious, often dense indumentum of forked or dendritically branched trichomes on the axes and leaf undersides, especially on young parts. Macbride (1962) differentiated these collections as S. luteoalbum var. tunya. Plants from further north in Depts. Huánuco and Junín usually have a few branched hairs on the axes and leaf midribs, but these are not nearly as noticable as in the collections from southern Peru. Collections from Ecuador and Depts. Cajamarca and Piura in Peru, as well as the types of S. pubescens and S. semicoalitum have exclusively unbranched hairs and numerous stalked glands. Whether these variants merit taxonomic recognition is debatable. Herbarium specimens from these areas do not have any obvious morphological differences except for indumentum characters.
Ruiz and Pavon (1799) described two species, S. foetidum Ruiz & Pav. and S. pubescens Ruiz & Pav., that may belong to the Cyphomandropsis group. Solanum foetidum, from Tarma, Peru, is described as a glabrous shrub with whitish-blue flowers, shining stems, and yellow fruits. Solanum pubescens, from Cuchero, Peru, is said to be pubescent, with whitish yellow flowers and orange fruits. A specimen at MA annotated as S. pubescens is very similar to plate 169 in Ruiz and Pavon (1799). No specimen or plate is known for S. foetidum. Both names are superfluous. Solanum foetidum Ruiz & Pav. is predated by S. foetidum Rottbøll (1778); Macbride (1930) provides the new name S. maleolens Macbr. for this taxon. Solanum pubescens Willdenow (1794) supersedes S. pubescens Ruiz & Pav., and Persoon (1805) provided the new name S. luteoalbum Pers. for it.
Ruiz & Pavon’s description, specimen and plate of S. pubescens conform to a species of section Cyphomandropsis. The only discrepancy is their description of the corolla color as “albo-lutescens,” whereas the plants listed here under their name have purple corollas. The situation with regard to S. maleolens (S. foetidum Ruiz & Pav.) is more confusing. The descriptions in Ruiz and Pavon (1799) are brief and rather vague, and without a plate or specimen for comparison, it is difficult to ascertain the application of this name. Dunal (1852) placed this taxon among members of Solanum section Geminata and he postulated that its affinities were with S. caavurana Vell. of that section. However, Dunal included many disparate elements under the name S. foetidum Ruiz & Pav. Macbride (1962) listed S. foetidum Ruiz & Pav. and S. maleolens Macbr. as synonyms of S. luteoalbum, but indicated in his discussion that more than one taxon may be present. Solanum foetidum and S. maleolens are regarded as doubtful names in Bohs (2001).
A single specimen of Cook & Gilbert 804 representing the type collection of S. luteoalbum var. tunya Macbride was examined from US. This specimen is not annotated by Macbride, and he gives no indication of the type location in his protologue. Nonetheless, since this is the only specimen that has been located of this number, it has been designated as the lectotype.