Question
Hi! I like asking you questions cause you're nice.
Here's a forum post I made on helpfulgardener.com, that I decided to ask you also:



This is my first serious year of gardening. I've always kept houseplants, but this year I began growing everything I could find.

This coming year of 2012, I want to start learning hybridization, cross pollinating and grafting.

I've decided to start with hibiscus, simply because I already have 2 growing in my yard.

However.... I need help.

One hibiscus is known as confederate rose and rosemallow. The other one is a pink rose of Sharon.

Can these 2 plants cross breed at all? either by grafting or swapping pollens?

If I buy other hibiscus, which ones can I get that CAN cross breed?

Personally I don't like the flowers on these, I much prefer the huge flowers that other hibiscus have.

Basically long story short, how do I know what types of hibiscus can cross breed?

Answer
Hi Desi,
Thanx for your question.  The matters you're asking after are a bit above my expertise.  I understand the basics of genetics but, I am by no means an expert.  I can tell you what I do know.  I know that hybridizing involves genetic compatibility.  Just like you can't breed a chicken with a horse, the same goes with the diversity of the plant kingdom.  So, you can't breed an oak tree with corn.  I believe the plants need to be from the same genus but the species may differ.  Or you can cross-breed within the species to isolate or improve upon certain desirable traits.  In the fruit tree world, breeders have been able to breed plums with apricots to create pluots and apriums because both fruits are from the genus Prunus and they are compatible with one another.  

The Confederate Rose is Hibiscus mutibilis and the Rose mallow is Lavatera trimestris.  I don't think these two are compatible because they are from different genera (plural of genus).  There has been a lot of cross-breeding done with Hibiscus.  Try the link below.  It is the American Hibiscus Society and I'm sure they would be happy to talk with you about breeding hibiscus.

http://americanhibiscus.org/

The other thing I would do is read some books on genetics.  Try some elementary books (beginner's books) first and then move on up as you get more experienced with the subject.  Then try plant genetics.  It's not complicated I just haven't gone into great depth learning about it as I have not had a need for it other than to get a decent grade for my College Biology class way-back-when.  ;oP

Now, Rose-of-Sharon is Hybiscus syriacus and it may be compatible with Confederate Rose.  Another thing you might consider doing is take a genetics course at your local community college just to learn.  I think getting involved with the Hibiscus society and learning from some of the folks there who do a lot of cross-breeding will be more valuable than anything else.  I hope this helps.
Tom