When a plant lists only the genus and then the cultivar, does this mean it is a hybrid cross of two different species?

That is what it means in some cases, but it also can mean that the species was left off the proposal when the addition of the plant to the database was proposed.

So, further research would seem to be in order (plus updating database if appropriate). Thanks. Does anyone know offhand if seedlings are more apt to come true from crosses within a species as opposed to two different species? Or is that variable? I'm trying to nail down a long spurred columbine that grows well in the PNW and hopefully doesn't throw seedlings that revert to plain-jane. I've got some potential cultivars from the PNW forum, doing additional research.

It also may mean that the breeder, or collector if it's a cultivar that was originally collected in the wild, simply doesn't know which species it belongs to. In this particular case, given how promiscuous columbines are, that's certainly a possibility.