• Phaeolus vulgaris are grown from the edible seeds contained in the fruit or pods of the plant.Jose Luis Pelaez/Stockbyte/Getty Images
  
  Phaseolus vulgaris is the common bean, and it includes kidney beans, white beans, long beans and most of the other edible bean varieties. There are 2,500 varieties of Phaseolus, including those that are trailing, vining or bush-like. The common bean is one of the most widely cultivated foods in the world. It is grown for the immature pods and seeds in the U.S., and for the seeds in other countries. The ease of cross-pollination in the genus has given rise to numerous flower colors.
  
  

Flower Parts

• Darwin was an early father of natural selection and an eager environmental scientist who performed many experiments on bean plants. He considered the bean plant's hormones, or auxins, which are ripening agents and spur flower development. Phaseolus vulgaris flowers develop the same in all the species. They have a standard petal and two side petals which are labled "wings." Two other petals grow together at the bottom and form a keel which coils itself back up and into the center of the flower. The coiled keel is a trademark of the genus Phaseolus.
  
  

Reproductive Organs

• The Phaseolus flower also contains central organs that promote and execute pollination and reproduction. The anther contains the plant's pollen, the pistil is the fruiting body which will become the bean after pollination, and the 10 stamens are outfitted to attract and spread the pollen. After pollination the pistil will elongate and enlarge, and the other parts will shrivel and fall off. The corolla and petals will dry up, and the anthers and stamens become part of the dried nub at the end of a bean as it forms. It will eventually scab up and drop.
  
  

Colors

• Much of Mendel and Darwin's experiments on morphology circled around pea plants. The morphological effects are similar in beans, especially where cross-pollination may have taken place, creating hybrids. Common bean flowers can be found in a variety of hues, including red, pink, white or yellow. Some of the coloring depends on the species, but the colors can also intermix on the same plant. Much of this difference in flower color stems from the auxin hormone triggers and from pollination variation. Legumes growing in a nearby field can be pollinated by a honey bee, which then brings that variety's pollen back to another species. The ability to accept alien pollen encourages the variety in Phaseolus vulgaris flowers.