A normal triple hybrid is shown thus:
A. chinensis × japonica × rosea

but one with an intermediate hybrid is shown as:
S. × multiflora × thunbergii
where S. × multiflora is itself a hybrid.

It appears that triple hybrids with intermediate hybrids can also be shown thus:
Lupinus × regalis × L. polyphyllus (Russel Lupin)
which is a hybrid of Lupinus polyphyllus (Garden Lupin) with the hybrid Lupinus × regalis.

Whereas a cross-hybrid between two plants in differing Genera is shown with a large and leading cross, as in:
X Gymnanacamptis anacamptis
which is a cross between Anacamptis pyramidalis (Pyramidal Orchid) and Gymnadenia conopsea) (one of the Fragrant-Orchids) [but this is not a triple hybrid, just a hybrid]. This example just goes to show that Genera are not totally distinct, and that many were derived from other Genera, some perhaps long since extinct. The whole of creation has been swapping genes between species, genera and families for millennia (probably not directly by sexual means, but via differing vectors, such as virii).