That's a great question, thanks for taking the time to ask it! Yes, for most plants if you put them in a cup with colored water you see that the dye is taken up the stem even if the plant is dead. But, it probably won't work as well on dried, dead plants. Try it with a celery stalk or a carrot (makes a nice art project). This is possible because the water and dye are drawn up the plant stem, or root, by capillary action and diffusion. Capillary action and diffusion are physical process that don't require any biological activity. An example of capillary action is if you take a dry towel and dip one end in the bathtub (in the water), and leave the other end on the floor; come back in a few hours and the towel will be completely soaked, and there will be a pool of water on the floor. Hope this answers your question and keep them coming!