dunno if this will clarify or not from my non-scientific viewpoint, but here goes. i had i. pennata for several yrs. then, after i got too vigorous in weeding that out, i found a source of seeds for i. quamoclit, which i'd seen and wanted really bad. anyhow, it seems more seedy/weedy than pennata, and comes up all over(no hope of weeding it all out)- but always with the extremely fine ferny foliage. i have some regular ipomeas(blue heaven, saucers, granpa otts, etc.- those are multifidas) that bloom at the same time and all over each yr, but have never seen them cross with or noticed any recognisable crosses of them and quamoclit(or pennata when i grew it). the common multifida ones cross every which way but loose with each other, but at least for me they haven't boogied with quamoclit. pup- i understood your question, but don't know the answer. it makes sense that it would be part of the genetic grab bag, but i haven't seen evidence of it. maybe your yard/experience is just that. i didn't mean that species don't or can't cross earlier, just that if the seeds are pure species, they should come true. we count on seedsman to label things correctly and breed them true. there's no way to really tell, though, just by the seeds(or plants), but i hadn't seen those 2 buggers cross or spontaneously mutate. however, because the common names are so similar, they certainly could get mixed up in a seed packet. and, who's to say some birds or storms didn't help along with some seeds from neighbor's yards? anyhow, i probably was making too many assumptions & should have kept my lip buttoned. i hope i didn't hurt any feelings. and, that's a good ? about what you call a species that can't cross. anyone?

I've grown both and have found that the cardinal climber isn't as invasive when it reseeds. I also like the larger cut of the foliage. The cypress vine is more fern like. I see some bindweed in that last picture too. :) I have some growing in the woods behind the house. The hummers love it too, but it is extremely invasive and reseeds with 100%+ germination.

Hyacinth Bean is supposed to grow well here in MI z5, gets quite large. It is an annual. Our local Garden Column writer had an article on it a while ago, as a suggestion for next summer. I think the flowers are pink. Moonflower might be a night-blooming vine to think about. Looks like white Morning Glory. Scent is very attractive for some folks. Also an annual. You might try starting some things from seed, get a head start. I always bought my Cardinal plants, so they got bloom time, were growing well before the end of summer. Clematis is a great vine, comes in many colors and various flower shapes. It is a perennial, so it can take a couple years to really get going well. However the flower reward is worth it, in my opinion. There are 3 bloom periods, which the different named plants can use. Some are early season, others mid-season, while others bloom in late summer, early fall. Just check the labels, so you know which time to expect bloom, when to trim the vines back. Lots of good information on the Clematis forum here on GW. I have had great luck with the clematis plants with Polish names, Pope John Paul II, and a purple one, can't remember it. Terrific bloom over long time period, starting the first year. I was pretty surprised at that. Has just gotten even better since!

Lary check out this site. You can get lots of help with plants for hummingbirds. There is probably someone here who has seeds for these vines and will be glad to share them. Someone is always sending seeds or plants to others. Here is a link that might be useful: Hummingbird Forum