Bees, Bats, Flowers…Pollination!

A View of One of the Most Important Natural Process

Posted on: June 24th, 2020

Sheltering-in-Place Blog Entry #11

Celebrating Pollinators Week!!

Pollen, that yellow stuff that looks like dust, floats in the air usually unnoticed, but one way or another, makes its presence known. Pollen is such a significant cause of allergies that a “pollen index” is reported on radio and television every day in some parts of the country. Allergies aside, pollen is a fascinating product of flowering plants. It’s the male reproductive cells of plants looking for a mate. Without pollen, there would not be fruits and seeds, which plants use to reproduce. Up close, pollen is also quite unique, with strange shapes, knobs, spines, and dimples. The form of the pollen grains is as unique as the plant species that produced them. They are often used to identify the plant species.

The rear legs of the honey bees have a special place where pollen gets collected. A messy job, it seems!
Euglosa sp. metallic bee carrying the pollinia (pollen sack) of a Gongora leucochila orchid. Their story is an amazing example of coevolution.

Pollen needs to get from one flower to the next to complete its function: meeting the egg, the female parts, and consummating the meeting of gametes. It is sexual reproduction in plants, although we’re not used to thinking of plants having sex. Some plants use the wind to spread their pollen. Oaks, cattails, and pine trees are all wind-pollinated. They produce lots of pollen that float in the air, sometimes traveling for vast distances. Some pollen will land on the “pistil” or female parts of a flower, germinate (literally, like microscopic little seeds), and perform the tiny miracle of fertilization. Other plants, especially those that do not produce such copious amounts of pollen, use different ways to spread their pollen from flower to flower—animals. And if you are thinking about bees, you would be right. Bees are pollinators par excellence, moving tirelessly from flower to flower, collecting pollen and nectar and helping plants reproduce. Without bees—and this is by no means an exaggeration—we would not have crops to feed us. We eat because bees and other insects help our food plants reproduce and produce fruits. Today’s worldwide bee crisis is due to the excessive use of pesticides. It’s a catastrophe in the making, all because we’re meddling in the underlying process of pollination. Our future depends on those little bits of pollen and on the bees and other creatures that move them from flower to flower. Just take a few moments and let that sink in.

Pollen is a beautiful thing. It preserves well in the fossil record within those jewel-like bits of fossilized resin called amber. It is even found in the sediments of old lakes and deeply buried forests, providing glimpses of the past and conjuring visions of ancient ecosystems long disappeared from the surface of the earth. 

A flower-loving bee fly (family Bombiilidae) visiting a Boraginaceae bloom. Can you see the spider waiting for an easy meal?

The story of the relationship between plants (through their flowers) and insects is a long-running “arms race.” Flowers need insects to move their pollen from one flower to another, so they entice insects through scent, color, nectar, and pollen itself. The insects use the nectar as an energy drink and pollen as food. Some, like butterflies, can actually live on nectar. Others use the pollen to feed their larvae. So, it is a mutually beneficial relationship. If the story ended here, it would be a good story. But a great story also has villains, and this story is full of them! Some insects bypass the elaborate adaptations of flowers and steal the nectar without helping the plant in its pollination. These nectar robbers include bees, wasps, beetles, and ants. Some are small enough to get to the nectar without touching the stamens laden with pollen, thus reaping the benefits without contributing to the plant. Others, the real villains, steal nectar by chewing holes near the base of the flowers, gaining access to the source of nectar, and essentially ruining the whole thing for everyone else. It must be frustrating and a waste of energy for a butterfly or a bumblebee to find a flower, land, reach in, and have its proboscis stick out into the air from the side of the flower through a hole. It’s something like inserting a straw into a can of soda only to realize it is empty. Plants have to deal with this all the time, and many produce enough flowers so that their true pollinators still do their job and receive their rewards.

Flowers and hummingbirds have a special relationship. They help each other accomplish important life functions.

But insects are not the only creatures that pollinate flowers. Birds and bats are excellent and effective pollinators, and many flowers have evolved, just like with insects, to accommodate different beaks, tongues, and heads. A bat hovering in front of a cactus flower, extending its tongue deep into the center of the flower and collecting a hefty spray of pollen on its chest or head, is something that few of us would ever see. But thanks to some fantastic filmmakers, these scenes are available and can fill us with awe and wonder (see links at the end). Hummingbirds and flowers have coevolved for tens of thousands of years to establish some beautiful relationships, where form and function, beaks and flower shapes, heads, and flower organs fit so perfectly as if to give us the impression of a design no engineer or supernatural entity could have ever planned. And here lies the beauty of pollination, and for that matter, the vast array of symbiotic relationships between plants and animals. Evolution is not a directed process with a beginning and an end. Evolution works with the raw materials produced by nature. It selects naturally those who can capitalize on the available resources and improve their chances of passing their genes to the next generation. Any physical or behavioral adaptation that enhances your chance of survival and reproduction will be favored through the genes that made it possible. And thus, tiny and consistent changes over time move the population of plants, animals, or both, towards a newer set of characteristics that improve the survival of both entities.

Another bee deep inside a bush mallow flower. Besides the huge pollen wads it has collected, lose pollen can be seen on its legs, thorax, and wings.

Next time you see a bee crawling through a cactus flower, or a butterfly fluttering above a goldenbush blossom, proboscis extended in search of nectar, or a hummingbird hovering in front of a flower, marvel at the glimpse in evolutionary time that made these creatures thrive in a perfect marriage.

 

LINKS TO EXPLORE

   Watch Bat Pollination here and here.

   An amazing video on the Beauty of Pollination: here 

  Learn about Pollinators and Our Gardens here 

   To learn about “Vitamin Bee” watch a fun program on Pollination for Kids here

 

 

 

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