Colorophyll

Ms. laura shares a great photo of a lettuce leaf and food colored water to demonstrate how water travels through a plant.

Good for ages 4 and up.

Get the instructions here:
http://www.flickr.com/photos/mslaura/4023084459/

Paint cut paste has a similar experiment using white carnations.

Get the instructions here:
http://paintcutpaste.com/color-changing-carnations/ 

All for kids has a non nature version of this experiment using tissue paper.

Get the instructions here:
http://allforkids.tv/episode-guide/season-4/episode-37/absorbing-science/

Apple green cottage has the same experiment.

Get the instructions here:
http://applegreencottage.blogspot.com/2015/01/walking-water-experiment-with-colors.html