Hi!
I haven't found anything about phytoestrogens in Rock Rose, perhaps it has some, like many plants do, but not much? It is a medical plant but more commonly used to increase immunity, against cold, infections, etc.
Soy is famous for containing a lot of phytoestrogens, and also linseed, sunflower seeds, pears, cherries, red wine, fruit peel (especially red grapes), lentils, broad beans, beans, wheat, barley, rye, pomegranate, cherries, dates, grapefruits, ginseng, celery, parsley, carrots, sesame... I read that to absorb phytoestrogens from plant food, one also has to have sufficient amount of fiber and probiotic bacteria (from fermented foods, yoghurt etc).
Why do you ask about fertility?
If it is to increase female fertility, simply taking phytoestrogens (and fiber and probiotics) will not be
enough; first one would need to do health tests to determine if there is a problem and what kind (blood tests, ovarian ultrasound, etc), and if she has a male partner, he
should also do fertility health check to see if the problem isn't on his part.
Please remember that this is not a medical advice!