I hadn't done this on purpose. I grew red and pink hollyhocks together, and this same plant seems to have produced a hybrid of both. is that possible?

Here is a link that might be useful: {{gwi:994626}}

Yes it is possible Mick, but it is equally possible that they were self pollinated, and carried the genes for that combination, from their parents. Only truly homozygous plants produce identical offspring when self pollenated. Many garden annuals and biennials from seed packets are F1 crosses from selected strains of parent and will carry mixed chromosomes, and produce a wide variety of types. When you find a trait that appeals to you, you can select your own strain by collecting seed from only the best of this type.
cheers, jan

I'm from the world of daylilies where the crossing is easy. Beyond that, I have no clue. Some guy up above talked about crossing a rose with a blackberry. How do I learn about this stuff?
Tim