Flowering Plants

This time of year there is an explosion going on. The woods around my house are exploding with flowers. Flowering plants, known as angiosperms, are one of natures great inventions. Of course I use the phase loosely, flowering plants came about due to evolution.

The first life on the planet was a very simple single-celled organism. Life was simple and relatively unchanged for a billion or two years until the evolution of a specialized type of organism known as cyanobacteria, often improperly referred to as blue green algae. These “critters” changed the world.

They were the first photosynthetic organisms which means they used sunlight to fix carbon from the atmosphere, producing oxygen in the process. It took another couple of billion years for the oxygen produced by these organisms to saturate the atmosphere to anything like the concentration that exists today.

It took another billion years for more complex, multi-cellular plants to show up on land, something that we would recognize as plants. Simple organisms such as mosses and liverworts were the first. Plant complexity expanded over millions of more years to include the gymnosperms. A giant leap evolutionarily occurred with the plant sex. This favored more rapid evolution and greater adaptability of plants. Pollen from pines is the male part of plant sexuality. I mean really, do the males have to coat everything for miles around with their sperm?

Last to show up evolutionarily in the plant kingdom are the flowering plants – the angiosperms. They date to about two hundred million years ago. The flowering plants including trees and grasses that now dominate much of the land surface of the globe. A key to the success of flowering plants are the symbiotic partnerships which form between pollinating organisms and the plants. Plants produce sweet nectar, attractive colors and odors all to attract pollinators. Some produce odors resembling that of a decomposing corpse to attract flies for pollination.

Hummingbirds just arrived at my feeder a couple of days ago. They always arrive with the blooming of trumpet honeysuckle. These long tubular flowers are adapted to and provide nectar for hummingbirds who act as the primary pollinators.

Some orchids induce pollination via male bees by producing a flower that actually stimulates the bee to have sex with the flower. The attraction is both physical and by odor – the orchid produces a pheromone used by female bees to attract males.

Seed dispersal is important to the success of flowering plants. The energy a plant expends to produce a succulent fruit will go a long way to aid reproduction via seed dispersal by the animal that consumes the fruit. Many plants produce attractive nutritious fruits but toxic seeds. The fruit is eaten but the seed then excreted undigested, with added fertilizer from the animal excreted with the seeds.

Dr. Bob Allen, Ph.D., is Emeritus Professor of Chemistry at Arkansas Tech University.


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