Sex Life of Plants

Sex life of plants is all about the birds & bees (bats too!)
Bay Naturalist / By Kathy Reshetiloff - Bay Journal

Imagine the world without natural fibers, fruits, vegetables or flowers. That’s what it would be like without the insects and other animals that pollinate our plants.

Two-thirds of our flowering plants are pollinated by insects, birds or bats; and more than three-fourths of the world’s crops rely on insects and other animals for pollination. The global economic benefit of pollination has been estimated at $117 billion. Pollination is critical to successful orchards, field crops, forage crops, home gardens, endangered species and ecological restoration.

As food producers and consumers, we all need to be aware of the importance of pollinators to plants and our environment. Most plants need to make seeds to reproduce. But many can’t do it by themselves. To make seeds, the female part of the plant, the pistil, needs pollen from the male part of the flower, the stamen.

In addition, cross-pollination is the rule of thumb in the plant world. Pollen from the stamen of one flower must be transported to the pistil of another so that the plant can make seeds and reproduce. Some plants rely on the wind to do this. Many others depend on animals to move pollen from one flower to another.

Insects, such as bees, get sticky pollen grains on their bodies while gathering nectar from flowers. As they move from one flower to another, bees transfer pollen to the pistils.

Bees aren’t the only pollinators, though. Other insects, such as wasps, flies, butterflies, moths and beetles are important pollinators. Larger animals, such as birds (especially hummingbirds), flying foxes, bats, opossums, lemurs, rodents and even a gecko, help to move pollen.

Plants need pollinators and vice versa. This co-dependence is exhibited in many ways. Many night-pollinated flowers close during the day, to prevent thieves from getting at their nectar and pollen. Many daytime-pollinated flowers close at night for the same reason. Flowers pollinated at night are usually white or pale yellow and very fragrant. This helps to announce the flowers’ presence. Darker-colored flowers, not as visible at night, are usually pollinated by day-flying insects.

Flowers also assist the pollinator in finding where the pollen or nectar is stored. Flowers often have bee lines — dots or color variations — that direct the pollinator.

Flowers come in many shapes: bowl, cup, star or tube. Shapes are specific to pollinators and, in some cases, also keep out unwanted pollen collectors. Some insects, like ants, love nectar, but are not good pollinators. Plants have developed protective devices, like closed throats or sticky hairs, that are designed to keep ants and other robbers out.

Other plants exude a sweet liquid on their stem to sidetrack unwanted visitors. Hiding nectar in tubes and closed blossoms has many advantages. If the nectar is hard to get at, usually only designated pollinators can find it.

Despite their importance to our economy and our lives, many pollinators are in trouble. Honeybees, raised specifically to pollinate crops, are in decline. One quarter of all managed hives have been lost since 1990, mainly because of parasitic mites, disease, pesticide poisoning and climate fluctuations. Wild pollinators are also disappearing at alarming rates, the result of habitat loss, pesticide poisoning, diseases and pests.

A healthy ecosystem provides pollinators with habitat for foraging, nesting, roosting and mating. Houses, businesses and roads are replacing the native fields, wetlands and forests that are home to many pollinators. In addition, many of the wildflowers that they feed on are rapidly disappearing.

Many of the pesticides used on farms and backyard gardens are broad-spectrum varieties that are not only toxic for plant pests but beneficial insects as well.

Pollinators such as bats, butterflies and hummingbirds face even more problems. They may migrate many miles over the course of a year and need nectar-producing flowers all along their journey. As wildflowers and natural habitats are being replaced by development, less food and habitat are available along the migration route. Migrating pollinators also have to deal with such threats as automobiles and pesticides.

There are many things each of us can do to help pollinators. Reduce the use of pesticides or, if possible, stop using them altogether. If you must use an insecticide, apply it in the evening, when many pollinators are inactive.

Restore or enhance wildlife habitat on your land by planting gardens filled with nectar-producing flowers that are native to your area.

Provide nesting sites for birds, bats, butterflies, bees and other insects. Leave tree stumps, dead branches and rotting trees on your property, if possible, as they provide nesting sites for some species of bees. If you find a bee nest too close to your home, don’t destroy it. Contact a local beekeeper or your state cooperative extension service for advice on how to remove the nest without harming the bees.

Kathryn Reshetiloff is with the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office in Annapolis.

Sex life of plants is all about the birds & bees (bats too!)
Article from Bay Journal - April 1999

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