Probably pointless to post in a thread this old, but what the heck. I grew up in central California, and there were a lot of crimson bottlebrush trees in my city. The only time in my life that I have ever broken out in a large blistery rash was on two separate occasions when I was exposed to pollen from these trees. On the first occasion, I stood directly under one for 20-30 minutes, waiting for a bus, and on the second occasion, I brushed up against a flower cluster on a short tree that was overgrowing a narrow path. On both occasions, the trees were in full bloom. I think it's the pollen that makes me break out. I found this thread while looking for information on similar plants that I might be allergic to, since I moved to a very different growing zone a while ago, and haven't thought to look before. I don't know if this is helpful, but it can be a relief to know that you're not the only person with that kind of reaction.