Pollination and "Floral Syndromes."

The pollination of plants arose about 15 million years ago with the plant group know as angiosperms. At that time there was also a dramatic rise in the number of insects that feed on flowers ( duh, angiosperms ARE the flowering plants!). While at first glance this would seem to be a reciprocal relationship of mutual bliss it's more like a battle of wills. Pollinators (insects, birds, small mammals) are seeking a food reward of pollen/ nectar and the plants are seeking to have as many pollen grains as possible transferred for the male parts of one flower (anthers) to the female parts ( stigma/style/ovary) of another flower.

Enter Vern Grant who in 1965 began to look into this concept of "mutual bliss" by watching hummingbirds and hawk moths. He noted that the length of certain tube shaped flowers almost exactly fit the proboscis/tongue/bill of the animals he observed. The animals were getting a food reward. In turn, the plants were depositing pollen in the right location on the animals bodies to have them transfer the pollen to the next flower and increase the odds of pollination occurring. Thus, through his observations, Vern Grant became enamored with the Phlox family and developed a theory of "Floral Syndromes." He felt that specific flower traits attracted specific pollinators. Bees, Grant noted, favored low growing, open faced yellow and or blue flowers (there seemed to be a short wave light/energy emitted from the blue flowers which was very attractive). Hummingbirds sought high growing or dangling red/yellow flowers with long tubes that held high amounts of nectar. Finally, hawk moths were feeding from pink and white (colors that show well at night, as many of these moths are nocturnal) flowers with tubular shape and high scent concentration. Vern Grant did not make a comparison study of flower scent and moth pheromones however, such research would prove both worthwhile and fascinating.

Upon first reading, all of Grant's research seems pretty straight forward. Yet modern day researchers are discovering that these "Floral Syndromes" don't always hold up. Calochortus amabilis exhibits traits that seem to come from two conflicting syndromes as it is yellow and low growing but it's flowers dangle downward and are somewhat closed. Likewise, hummingbirds are known to frequently visit penstemen which are blue/violet in color. These visitations again break the syndrome rules. Most disturbing is that even if a flower is of a "specialized" color and shape, over time it is visited by a broad spectrum of pollinators. This begs the questions of why do all these pollinators visit and why did the flower bother to specialize in the first place if it is not certain to reap benefits from that specialization?

Modern day entomologist and plant biologist are focusing into what could be loosely termed "the good, the bad, and the ugly" of the pollination world. Hummingbirds would be an example of a good pollinator which removes and deposits almost all of flowers pollen. Hawk moths would be bad pollinators as they do not remove much pollen from the flowers. Bees would be ugly pollinators as they remove a great deal of pollen but, as bees feed upon pollen, they do not deposit much pollen.