When I paint a flower I like to use one that I find in my garden and paint it in place. While I may not have access to the flower from my window I take several photographs from many different angles and then bring these into my studio. Once I have these photographs I make a choice whether I think the character of the particular flower lends itself more to a gestural interpretation or something more 'natural' or realistic.
For Hollyhocks, I love the wild abandon in which they throw their petals out from the stem. So I choose 'gestural'. Here I don't worry about realism or exactly where each petal will go but aim for the emotion of the flower. Watercolor lends itself to this extremely well. In the photo below I used watercolor canvas so I could pull the color off and create negative spaces.
Sometimes Irises have that same wild flurry of motion and the second painting below is done on watercolor paper and only captures the essence of the flower I was painting.