Solanum amygdalifolium
In chaco vegetation along streams and rivers, in thickets and in open vegetation in the Río de la Plata drainage from Buenos Aires, Argentina and adjacent Uruguay to the upper Río Pilcomayo in Paraguay, and in coastal Brazil from Bahia south to Rio Grande do Sul, from 0-700 m elevation. Solanum amygdalifolium is also cultivated outside of its native range for its showy flowers (Bolivia, Andean Argentina).
Solanum amygdalifolium is a member of the Dulcamaroid clade (sensu Weese & Bohs, 2007), and in that molecular analyses is part of a polytomy with the few other members of the clade included.
Dunal, M.F. 1852. Solanaceae.
Pp. 1-690 in A. P. DeCandolle (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 13(1). Victoris Masson, Paris, France.
Morong, T. & N.L. Britton 1893. An enumeration of the plants collected by Dr. Thomas Morong in Paraguay, 1888–1890.
Annals of the New York Academy of Sciences 7: 45–280.
Morton, C.V. 1976. A revision of the Argentine species of Solanum.
Pp. 1-260. Academia Nacional de Ciencias, Córdoba, Argentina.
Cabrera, A. 1983. Solanaceae.
In Flora de la provincia de Jujuy, ed. A. Cabrera, 292-493. Buenos Aires, Argentina: Instituto Nacional de Tecnología Agropecuaria.
Mentz, L.A. & P.L. de Oliveira 2004. Solanum (Solanaceae) na região sul do Brasil.
Pesquisas, Bot. 54: 1-327.
Weese, T.L. & L. Bohs 2007. A Three-Gene Phylogeny of the Genus Solanum (Solanaceae)
Syst. Bot. 32(2): 445-463.
Solanum amygdalifolium occurs over a very broad geographical range in association with fresh (non-brackish) water, and has been characterised as semi-aquatic by some authors (Mentz & Oliveira, 2004). In chaco habitats in Paraguay it always grows in riverside thickets, and forms loose scrambling tangles. With its very large, showy flowers, strongly angled stems and narrow, simple leaves, it is not easily confused with any other species of the Dulcamaroid clade; it is somewhat similar to other Dulcamaroids from southern South America, particularly narrow-leaved specimens of S. flaccidum, but the smaller flowers, more pubescent leaves and unequal filaments of the latter species are distinguishing features. Solanum flaccidum grows in completely different types of habitats than does S. amygdalifolium, so confusion in the field is unlikely.
In general, S. amygdalifolium is quite monomorphic vegetatively over its broad range, varying only in degree of pubescence between individuals and somewhat in inflorescence size depending on plant age, but the flowers of plants from the Chaco regions of Argentina and Paraguay are much larger than those of plants from more coastal populations near the mouth of the Río de la Plata in Buenos Aires and adjacent Uruguay. Flower size may also have something to do with water availability, as plants collected from near streams and wet places in the wet season all appear to have larger flowers than those from drier areas. The specimens collected in the foothills of the Andes in the province of Jujuy, Argentina appear to have all been from cultivated plants (Cabrera, 1983).
Several collections were cited in the original description of Solanum persicifolium; one of these will need to be selected as the lectotype. Martius 255 appears to be the more widely distributed of the syntypes cited in the protologue.
Morong (Morong & Britton, 1893) clearly intended Solanum handelianum as a replacement name for S. angustifolium Lam.; he cites “S. angustifolium Lam., Illus. no. 2343, not Miller” and although he cites a collection of his own from near Asunción in Central Paraguay (Morong 818), he does not append “n.sp.” to the epithet as he does for all new taxa he described in 1893 from his own collections.