Drama on the Flowers

Bright yellow goldenbush (Isocoma menziesii) flowers nod in a gentle afternoon breeze. Its late fall on Catalina Island and the splash of color catches your eye. Up close, a drama is unfolding. Numerous bees hover over the expanse of flowers, a butterfly awkwardly scuttles off to visit the delicate flowers of the narrow-leaf milkweed (Aesclepias fascicularis), a fly struggles to extract itself from a spider’s web, and ants are swarming on the flowers and running up and down the stems of the plants.

What else is going on? A number of dramas unfold every day in and among the flowers of Catalina’s plants. The interaction between plants, insects, and animals illustrate several ecological concepts in very dramatic ways.

The first concept is that the more complex the flower, the more likely that it has evolved specifically for pollination by a very specific group of insects. And, the insects more than likely have developed specific characteristics that take advantage of these plants. This is known as co-evolution.

Many plants reproduce sexually by producing male and female “gametes” in the form of pollen and eggs that when joined will form the seeds for the next generation.  Sexually reproducing plants use flowers in the production and packaging of these gametes and many of these flowers use insects as the means to transport their gametes to other flowers.  A pollen-laden insect is a great reproduction messenger, bringing the pollen from flower to flower ensuring that a plant will not self-pollinate something that for some plants is not a good thing. 

Where there is nectar, there are nectar-feeders, and where these are, there is likely to be a predator around. This is the next piece in the complex web of life. Spiders, ants, praying mantises, wasps and other creatures, including lizards and frogs, hang around flowers because of the abundance of potential prey.  Some, like Argentine ants, attack visiting insects to the flowers either to catch and kill them or to defend other plant-associated resources, such as aphids. Aphids secrete droppings in the form of “honeydew.” Honeydew is the clear, sticky dropping that lands on the leaves or anything below the plant or tree that aphids are feeding upon.  Aphid colonies are protected by the Argentine ants. In return for this protection the ants are allowed to collect the sweet honeydew as a source of food.