Here are a couple of interesting images. Last year I ordered a couple of bulbs of
Fritillaria grandiflora, but the seller sent me one bulb of
grandiflora and one of
kotschyana by mistake (some, such as the Fritillaria group, have these as forms of the same species). The two bulbs were planted in the same pot, so had the same treatment and were in close proximity, maximising the likelihood of cross-pollination.
The first image shows examples of the seed. On the left, seed from kotschyana, and on the right, grandiflora. You can see immediately a difference in colouration, but also in the shape of the seed (grandiflora are rounder with a tendency for the bottom edge to be concave and a narrower edge; kotschyana have a more triangular shape with a wider edge).
The second image shows the amount of chaff. I had one pod from each bulb, and more than half of the seeds from each was non viable. Seed set was poor. You would expect this situation if a clone was selfed, but not if cross pollination had occurred and the resulting crosses were fertile. Maybe this just reflects the cold spring we had and poor conditions for pollinators. But an alternative explanation is that grandiflora and kotschyana don't cross easily.
Are these two really just forms of the same species? My own view is probably not, though I don't really have enough experience with either to know for sure.
