Uses for Rose Leaves and Stems

I have been a faithful visitor to your site since I found it and really enjoy it. I was wondering if you could answer a quick question: are there any properties in the stems and leaves of roses?
I am making a rosewater decoction right now with the petals – I know, can you believe it I am actually doing this?! – but I thought, what a waste of the stems and leaves. What if I throw them in the coffee grinder and then made a decoction with that and then combined the two?

Rose hips and flowers are what are used mostly. Almost always it is these two plant parts that are mentioned in standard herbal references. Gerd Kruessmann, in his book "The Complete Book of Roses," says that the leaves have been used for medicinal purposes. He says that medieval chemists sold "Turkish Rose Pearls" which were shiny black pills made from powdered rose leaves mixed with gum. He guesses they were used for toothache, but does not say which species was used. He also says that the leaves of one species, Rosa pomifera, were used for an infusion called "German Tea," but he does not mention for what purpose. The root bark and seeds were also used for medicinal purposes.
What would happen if you throw ground up stems and leaves in your decoction, we cannot say. We did not find evidence of any danger in using these plant parts, and there is some evidence that the leaves, at least, were used safely in the past.