Pollination

The German physician and botanist Rudolf Jakob Camerarius (1665-1721) is credited with the first empirical demonstration that plants reproduce sexually. Camerarius discovered the roles of the different parts of a flower in seed production. While studying certain bisexual (with both male and female reproductive organs) species of flowers, he noted that a stamen (male pollen-producing organ) and a pistil (female ovule-producing organ) were both needed for seed production. The details of fertilization were discovered by scientists several decades after Camerarius's death.

Among the many other scientists who followed Cam erarius's footsteps in the study of pollination, one of the most eminent was Charles Darwin. In 1862, Darwin published an important book on pollination: The Various Contrivances by which Orchids Are Fertilized by Insects. In part, Darwin wrote this book on orchids in support of his theory of evolution proposed in The Origin of Species, published in 1859.

Darwin demonstrated that many orchid flowers had evolved elaborate structures by natural selection in order to facilitate cross-pollination. He suggested that orchids and their insect pollinators evolved by interacting with one another over many generations, a process referred to as coevolution.

One particular example illustrates Darwin's powerful insight. He studied dried specimens of Angraecum sesquipedale, an orchid native to Madagascar. The white flower of this orchid has a foot-long (30 cm) tubular spur with a small drop of nectar at its base. Darwin claimed that this orchid had been pollinated by a moth with a foot-long tongue. He noted, however, that his statement "has been ridiculed by some entomologists." And indeed, around the turn of the century, a Madagascan moth with a one-foot-long tongue was discovered. Apparently, the moth's tongue uncoils to sip the nectar of A. sesquipedale as it cross-pollinates the flowers.

Darwin continued his studies of pollination in subsequent years. In 1876, he wrote another important book on pollination biology, The Effects of Cross and Self Fertilization in the Vegetable Kingdom.

The Austrian monk and botanist Johann Gregor Mendel (1822-1884) also conducted important pollination studies in Brno (now in the Czech Republic) in the mid-1800s. He studied heredity by performing controlled cross-pollinations of pea plants thereby laying the foundation for the study of heredity and genetics.