I've never seen its seeds, but, then, I've never looked. S. leucantha flowers readily here in summer (Temecula, Calif.). It's a popular landscaping plant in so.Calif. It is suseptable to frost, though. Ours was killed back to the ground by 23F (about -5C) in Jan 2007, and the plant is only now really looking right. Hummingbirds like them. I only have one plant, since I've been concentrating on native Calif. salvias, but some new home tracts that I've worked at had large plantings of them, and they were defended by Costa's Hummingbirds.

Robin:
S.leucantha does not produce seed here (in the ground).
I would think it possible to get seed if put in a greenhouse
so that seed would have time to mature before freezes. Just a thought it produces pollen but plants like S.elegans and chiapensis produce seed before leucantha does.
So those hybrids "Seed Parent" would be elegans/chiapensis.while leucantha's nonation is just pollen.Another possible way this could happen is that plants shipped from a southern
location in bloom to a northern location(in spring) would have time for the seed to finish rippening.Thus producing offspring.Just speculating. I have never seen this plant in the wild in Mexico.
Art