Hello Uli: I have got seed from Oxalis obtusa, O. commutata and O. comosa. I should emphasize though that I have many different clones of each of these species. I haven't noticed seed on any of my other oxalis (about 250 taxa, maybe more). I don't WANT seed production, so I have moved the different clones to different places so they can't pollinate each other. The worst thing in an oxalis collection is getting contamination of your pots by seed dropping in nearby containers. I very carefully watch for seed pods, but they can pop before you know it! I have never found any hybridization. I have different colors of O. obtusa showing up, though. Michael Vassar thought that the color in O. obtusa is unstable and can change from one year to another, but I wonder if it's from seedlings? My O. obtusa certainly change their intensity of color according to weather conditions, and, for the most part, are a bit more intense here with lower light than they were in the much brighter sunnier winters of the interior of California. Diana