Are you sure there is only one trunk coming out of the ground? I bought one several years ago that was supposed to be double lavender. It had two trunks. One plant is lavender and the other is the double deep pink (so called red). I do know that some of the mail order nurseries (i.e., Burgess, Henry Fields, Four Seasons)advertise grafted altheas with different colored blooms on one bush. I would guess you may have one of these.

Thanks for the helpful response. Our Althea is a cluster of trunks and it now appears that there are two different varieties planted together as one.

sure is pretty!

My Althea has lots of buds, but they never open up. HELP!