This is an easy experiment where you put a white flower into a recipient filled with water and liquid watercolor, so that the flower gets dyed.
While doing this experiment for different types of flowers, and assuming equal ambient conditions, what would be the most important characteristics (e.g. flower size, petal length, stem thickness, number of petals...) and the biological reasons for certain flower type to consume water (and get itself dyed) faster than another? (e.g., does a thicker stem mean the xylem is stronger?)
More specifically, I'm interested in comparing a rose like this and a carnation (like the one shown in comments) as an example to the answer.
(Note: I couldn't show a carnation sample image due to my reputation being lower than 10, but I'll update it as soon as I can).