When a pollen grain moves from the anther male part of a flower to the stigma female part , pollination happens.
This is the first step in a process that produces seeds, fruits, and the next generation of plants. This can happen through self-pollination, wind and water pollination, or through the work of vectors that move pollen within the flower and from bloom to bloom.
Birds, bats, butterflies, moths, flies, beetles, wasps, small mammals, and most importantly, bees are pollinators. They visit flowers to drink nectar or feed off of pollen and transport pollen grains as they move from spot to spot. Pollinators provide pollination services to over , different plant species and more than crops.
That means that 1 out of every three bites of food you eat is there because of pollinators [ 2 , 3 ]. If we want to talk dollars and cents, pollinators add billion dollars to the global economy [ 4 , 5 ], and honey bees alone are responsible for between 1.
In addition to the food that we eat, pollinators support healthy ecosystems that clean the air, stabilize soils, protect from severe weather, and support other wildlife [ 7 ]. Pollinator populations are changing. Many pollinator populations are in decline and this decline is attributed most severely to a loss in feeding and nesting habitats [ 8 , 9 ]. Pollution, the misuse of chemicals, disease, and changes in climatic patterns are all contributing to shrinking and shifting pollinator populations.
Pollinators need help, but we know how to help them! The successful transfer of pollen in and between flowers of the same plant species leads to fertilization, successful seed development, and fruit production. Other factors such as drought, extreme temperature shifts, or diseases may prevent full fruit and seed production.
For more information, also see The Birds and the Bees. Flowering plants have co-evolved with their pollinator partners over millions of years producing a fascinating and interesting diversity of floral strategies and pollinator adaptations. The great variety in color, form, and scent we see in flowers is a direct result of the intimate association of flowers with pollinators.
The various flower traits associated with different pollinators are known as pollination syndromes. Flowering plants have evolved two pollination methods: 1 pollination without the involvement of organisms abiotic , and 2 pollination mediated by animals biotic.
Plants that use wind for cross-pollination generally have flowers that appear early in the spring, before or as the plant's leaves are emerging. This prevents the leaves from interfering with the dispersal of the pollen from the anthers and provides for the reception of the pollen on the stigmas of the flowers. In species like oaks, birch, or cottonwood, male flowers are arranged in long pendant catkins or long upright inflorescences in which the flowers are small, green, and grouped together, and produce very large amounts of pollen.
Pollen of wind-pollinated plants is lightweight, smooth, and small. Grasslands ensure successful wind pollination through sheer number of flowering plants and the large quantities of pollen released. Photo by U. Forest Service. Inset photo: A grass plant Bouteloua gracilis in anthesis anthers releasing pollen. Photo by Steve Olson. Some plants such as Erythronium grandiflorum stagger the timing of pollen release to increase visitation by pollinators and lower the chances of self-pollination. Wind-pollinated species like this cottonwood releases copious amounts of pollen from its catkins before the tree leafs out.
Photo by Teresa Prendusi. Clouds of pollen rise above an Engelmann spruce forest. Photo by Al Schneider. The long days of summer provide pollinators the maximum time to forage for nectar. Fall: Late blooming plants provide many pollinators with needed fuel before hibernation or for the southern migrations of pollinators like monarchs and hummingbirds. Winter: Even when there appears to be little to no activity, pollinators are in the garden.
Leave decaying plants alone—they may be sheltering pollinating insects as they overwinter. Do you know some butterflies travel thousands miles? At the beginning of each spring, monarch butterflies migrate north from Mexico, following the growth of milkweed. They travel up to 30 miles a day, returning to Mexico in the fall. Pollinator habitat depends on the pollinator and their life cycle stage. For example, bees can use leaves, mud, sand, plant resins and even abandoned snail shells for their nests, while many butterfly larvae live and feed only on one specific plant.
Pollinator habitats need to be within easy range of food and clean, shallow water. Do you know how bees find a flower patch? Honey bees communicate through a waggle dance in which scout bees return to the nest and dance to inform other bees about the distance and direction of a newly discovered flower patch.
Plants and pollinators evolved side by side over millions of years. Natural selection has resulted in physical adaptations in both plants and pollinators. Plants developed many complex ways of attracting pollinators.
Similarly, pollinators evolved with specialized physical traits and behaviors that enhance their pollination efforts. Each participant, plant and pollinator, usually gains a benefit from pollination. Bees: Flower nectar provides bees with the sugar to fuel their flights.
The proteins and amino acids in pollen are vital nutrients needed by young bee larvae back in the next. Bees are not picky and frequently visit a large variety of flowers. Less elegant than other pollinators, beetles blunder their way through delicate blossoms searching for food, a mate, or perhaps the bathroom. Beetles frequently visit magnolias and flowers close to the ground. Butterflies: Butterflies often visit round flowers with flared petals that lead to narrow throats that conceal nectar.
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