Homology: Leave It To the Plants
In the following photos of plants, the leaves are quite different from the "normal"
leaves we envision.
Each leaf has a very different shape and function, yet all are homologous structures,
derived from a common ancestral form. The pitcher plant and Venus' flytrap use leaves
to trap and digest insects. The bright red leaves of the poinsettia look like flower
petals. The cactus leaves are modified into small spines, which reduce water loss and
can protect the cactus from plant-eaters.