This led me to some interesting reading. There are some published studies and reviews looking into the genetics involved. They discuss Belgian azaleas, suggesting that rhododendrons in general might be susceptible to this.
As I understand it - and at this point I’m spelling things out for myself, as I’m sure you’re probably way ahead of me here, Neil - there’s a phenomenon called ‘bud sporting’ in any plant, where a somatic mutation leads to different growth pattern in one branch / flower etc, which can then be propagated. It seems that azaleas (and camelias?) are rather susceptible. The satsuki in particular are genetically unstable enough to reliably bud sport, so they can have a mix of flowers each season (a trait that’s probably been cultívated). Variegation appears to be due to mutant tetraploid petal segments developing alongside the normal diploid ones, which occurs in a branch that is itself more genetically unstable than the other branches on the tree with monochrome flowers.
This is pretty superficial reading on my part, I’m sure there are others in the forum able to explain it better and correct me if I’ve totally misunderstood this. Interesting regardless!
https://www.researchgate.net/publicatio ... our_sports
https://www.sciencedirect.com/science/a ... 9915303331Yes, the username is misspelled: no, I can’t change it.
Andy
Both the flowers are on stems growing from the same trunk.
