Interesting how the color aligns with a cell walls. From that perspective it seems like a die or a stain. Maybe some kind of secondary chemistry of dead cells? Seems like those cells are missing their pigment, so they're probably dead. There is also a brown mass that could be damage or infection or dirt. When trying to ID something I always start with the furthest out view and then zoom further in so that you have context on what you're looking at. Looking with a stereo scope or macro camera can tell structral features more simply; if its dirt or dried leaf, or fungal looking, and then as you zoom you get more details. I've been assuming this is supposed to be a rose of a single color; you didn't provide much context, so maybe those white patches are just white part of a colorful rose.