Solanum carolinense var. floridanum
Wahlert et al. recognise 2 varieties of Solanum carolinensen distinguised in the following key:
KEY TO THE VARIETIES OF SOLANUM CAROLINENSE
1. Leaf margins subentire, sinuate, or lobed; sinuses of lobes, when present, reaching less than half the distance to the midvein; apex of leaf lobes subacute to acute, sometimes rounded…………………………..….Solanum carolinense var. carolinense
1'. Leaf margins deeply lobed to parted; sinuses of lobes reaching more than half the distance to the midvein or almost to the midvein; apex of leaf lobes typically rounded……………………………………………Solanum carolinense var. floridanum
D'Arcy (1969) reports a gametophytic chromosome number of n = 12 [D'Arcy 3500 and 3501 (FLAS)].
Solanum carolinense var. floridanum occurs primarily in Florida in the vicinity of the Suwannee, Apalachicola, and Aucilla Rivers in the Gulf Coast region and near the Atlantic coast in the northeastern part of the state. The variety is also known from several localities in the coastal plain of Georgia. It often grows in moist areas and on sandy river banks, but also in slash pine–palmetto woodlands and roadsides. The variety grows at elevations from sea level to ca. 10 m.
Solanum carolinense var. floridanum is a member of the Carolinense calde (sensu Stern et al. 2011) [section Lathyrocarpum]. Relationships amongst species in the group have been analyzed by Wahlert et al. (2014).
D'Arcy, W. G. 1969. Chromosome numbers of phanerogams 3. Annals of the Missouri Botanical Garden. 56: 471–475.
D'Arcy, W. G. 1974. Solanum and its close relatives in Florida. Annals of the Missouri Botanical Garden 61: 819–867.
McNeill, J., F. R. Barrie, W. R. Buck, V. Demoulin, W. Greuter, D. L. Hawksworth, P. S. Herendeen, S. Knapp, K. Marhold, J. Prado, W. F. Prud'homme van Reine, G. F. Smith, J. H. Wiersema, and N. J. Turland. 2012. International code of nomenclature for algae, fungi and plants (Melbourne Code). Regnum Vegetabile, 154. Liechtenstein: A. R. G. Gantner Verlag KG.
Stern, S., M. F. Agra, and L. Bohs. 2011. Molecular delimitation of clades within New World species of the "spiny solanums" (Solanum subg. Leptostemonum). Taxon 60: 1429–1441.
Wahlert, G. A., F. Chiarini, and L. Bohs. 2014. Phylogeny of the Carolinense clade of Solanum (Solanaceae) inferred from nuclear and plastid DNA sequences. Systematic Botany 39: 1208–1216.
Commonly known as Florida horsenettle (e.g., J. Scanlon & T. Matthews 138).
Solanum carolinense var. floridanum is known from ca. 27 locations, several of which are situated in protected areas (Waccasassa Bay State Preserve, Chassahowitzka National Wildlife Refuge, Aucilla Wildlife Management Area, Torreya State Park, and St. Mark's National Wildlife Refuge). Because it grows in highly disturbed areas such as roadsides, cultivated fields, and grazed pastures, it is estimated that there will not be any significant reduction in population size or locations; with an extent of occurrence of ca. 35,000 km2 and area of occupancy of 480 km2, S. carolinense var. floridanum is assigned a preliminary conservation status of "least concern" (LC).
Solanum carolinense var. floridanum has sometimes been treated as a synonym under S. carolinense var. carolinense or recognized at the rank of species (i.e., as S. godfreyi Shinners), but we agree with D'Arcy (1974) and others that the taxon is best maintained the rank of variety. While var. floridanum is very similar to var. carolinense, its deeply lobed leaves and rounded leaf lobes, preference for moist habitats, and mostly distinct distribution from var. carolinense support its continued recognition as a variety. Sometimes intermediates between var. carolinense and var. floridanum occur and a definitive determination cannot be made (e.g., E. West & L. E. Arnold s. n. [FLAS, GH-n.v.]; R. L. Nichols s. n. [MO]).
Solanum floridanum Dunal (1852) is an illegitimate later homonym of S. floridanum Raf. (1840). Shinners (1962) recognized the taxon at the rank of species and provided the replacement name S. godfreyi Shinners. D'Arcy (1974) mistakenly cited the specimen R. K. Godfrey 60037 as the type of S. godfreyi, but under Art. 7.3 of the Code (McNeill et al. 2012), the type of the replacement name is typified by the type of the replaced illegitimate homonym (in this case, F. I. X. Rugel s. n.). According to Art. 58 of the Code (McNeill et al. 2012), the name S. carolinense var. floridanum Chapm. is correct when this taxon is recognized at the rank of variety. This article states that when the epithet of an illegitimate name is used in a combination at a different rank, the resulting name is treated as a nomen novem and priority does not date back to the publication of the illegitimate name. [note: if this taxon were recognized at the species level the correct name woudl be Solanum godfreyi Shinners]