Observations and results
Did you find that most (or all) of the red flowers used the same pigments? Did the pigments create a reddish-purplish band on the paper towel strips?
Carotene pigments (which are carotenoids) produce yellow, orange and red colors whereas anthocyanin pigments (which are flavonoids) produce red, purple, magenta and blue colors. Most red flowers use anthocyanin pigments to produce their red coloring (although some use carotenoids). On the paper strips, the anthocyanin pigments may have appeared as a purplish-reddish band. If different red flowers made similarly colored bands around the same height on the paper towel strip as one another, then they likely have the same pigment. If the bands are different colors and/or at different heights, however, then they're probably different pigments. Carotene pigments are more commonly found in vegetables, and, in fact, they are what make carrots look orange. Yellow and orange flowers can have carotenoids or flavonoids, and blue flowers often have anthocyanin pigments that are modified. Some flowers even have chlorophyll that gives them green coloring.
In paper chromatography the pigments move up the paper with the liquid and are separated based on the solubility of the pigments. So, if a pigment is very soluble in the diluted isopropyl rubbing alcohol, it should be easily carried far up the paper strip whereas a less soluble pigment will generally travel a shorter distance. Because different pigments often have different solubilities, they can be separated from one another on the paper strip.
More to explore
What Pigments are in Fruit and Flowers? from WebExhibits
The Chemical Pigments of Plants ( pdf ), from Joy Alkema and Spencer L. Seager, Weber State University, Ogden, Utah
Paper Chromatography , from Chemguide
Reveal the Red: Exploring the Chemistry of Red Flower Pigments , from Science Buddies
This activity brought to you in partnership with Science Buddies