On Flora of North America, it mentions this:
"Many previous authors treated Cissus incisa and C. trifoliata as distinct species, but the characters used to separate them (size of leaflets, branching patterns of cymes, and berry shape) appear to intergrade abundantly, particularly in Florida, where their geographical ranges overlap. It appears that much of the basis for separating these two species is geographical distribution and habitat, with C. trifoliata being chiefly coastal and tropical and C. incisa being chiefly subtropical and temperate continental. Some authors (for example, R. P. Wunderlin 1982; R. K. Godfrey 1988; J. A. Lombardi 2000) therefore have treated C. incisa as a synonym of C. trifoliata, a conclusion that is followed here."
Torrey, John, and Gray, Asa: A Flora of North America, Containing Abridged Descriptions of All the Known Indigenous and Naturalized Plants Growing North of Mexico, Volume I. Wiley and Putnam, 1838-40. (Ligação)
Unintended disagreements occur when a parent (B) is
thinned by swapping a child (E) to another part of the
taxonomic tree, resulting in existing IDs of the parent being interpreted
as disagreements with existing IDs of the swapped child.
Identification
ID 2 of taxon E will be an unintended disagreement with ID 1 of taxon B after the taxon swap
If thinning a parent results in more than 10 unintended disagreements, you
should split the parent after swapping the child to replace existing IDs
of the parent (B) with IDs that don't disagree.