I don't know the answer to your particular cross pollination question, but I can tell you that unless you are collecting this year's seeds to sow in the future, it won't matter if they cross-pollinate or not. In other words, your plants will develop from true from professional seed sources and no matter how busy the bees are, they won't revert to anything else mid season. The genetic information is transferred to the SEED, not the flower.

Cross pollination is a much favored 'policy' in the natural world, where hybrid vigor is very important. Indeed, many plant require cross pollination in order to produce fruit at all! But it is the seed within the fruit that will exhibit the results of crossing, not this season's fruit and flowers.

Hmmmm, have I confused your question? It's a good one! Cross-pollination is a topic that is much misunderstood, that's for sure. Please tell me if I've missed the point of your question entirely.

rhizo, Your explanation makes sense. I'm not sure if I explained it right or not but my concern was this: If I would plant both of those kinds of lupines in close proximity to one another, I'm afraid that they might cross. I understand that the existing original plants (as soon as they're actually there) will always be the same and their being close to each other wouldn't change those first plants. I just don't know if the seeds that would be produced on the plants would result in a new kind of plant if those seeds would drop to the ground and produce new plants. I guess if nobody really knows the answer to that, I think I'll play it safe and plant them pretty far from each other, although I had been planning on planting them in the same flower bed originally. I like to give away seeds of my plants and didn't want to claim that a certain packet of seeds was L. perennis when they might have gotten crossed with the other lupine. If that would happen, I don't know if the Karner Blue would eat the plants that would grow when those seeds are planted. I doubt if I can get the Karner Blue here since it's only in two counties (I think) in PA and they are way up north and east of me. I'd hate to send seeds out to someone who is in Karner Blue territory and they wouldn't eat the plants.
Thank you for your explanation.
Cathy