Rose of Sharon Pollen on water POLLEN GRAINS ARE PRODUCED IN THE MILLIONS FOR WIND POLLINATED, AND ALLERGY –INDUCING PLANTS OR THOUSANDS, AS EXEMPLIFIED BY THESE POLLEN GRAINS FROM AN INSECT POLLINATED ROSE OF SHARON
"Have you ever wondered how plants have sex? Just like humans, plants produce eggs and sperm that have to come together to create the next generation, and just like humans, eggs and sperm are produced in separate regions of the plant body and sometimes in separate plants. And just like humans, eggs are fertilized by sperm to create the next generation. We all know how sperm and egg come together in humans, but how does sperm find its way to eggs in plants?
Plant eggs are fixed inside incipient seeds in very young fruits, so sperm has to be carried to them. Plant sperm is produced in miniature packets called pollen grains that either have to be small and smooth so they are carried by air currents, or larger and sticky so they can be carried by animals (usually insects and sometimes humming birds) to the young fruits developing inside flowers. Once they reach the flower, they have to be snagged out of the air or rubbed off the animal bodies by the sticky surfaces called stigmas in the middle of flowers. The pollen grains grow through the stigmas and down through another flower part (the style – you know styles – the silk of corn, and the expensive spices called saffron are styles) with corridors that lead to the private chambers where the eggs are held (in the ovaries). The pollen grain produces a special tube that delivers the sperm to the egg. Once there, fertilization takes place, seeds, and plant fruits (the mature ovary – think an apple with seeds in it) begin to develop.For centuries, botanists have puzzled over questions like how many different types of pollen grains can land on the sticky surface of the young fruitstigma before it becomes clogged with the wrong pollen? How does the pollen grain and the surface of the stigma know they have made the right match? How much pollen lands on the wrong part of the flower and is wasted? Do plants release pollen at times before or after the stigmas are receptive in order to prevent inbreeding?
Answers to these questions are key to understanding why there are so many different types of plants, why plants need to match their flowering time to the time of year that the animal pollinators are around, and why farmers need to carefully plan the when to release bees and how many. Few of us think about the fact that these tiny packets of pollen, of which there are billions floating around us every day (the ones carried by the wind are a source of allergies for some people), are critical to our survival. That is, all humans depend on plant fruits and seeds for sustenance, directly for most of the world, and indirectly for those who eat meat – derived by feeding farm animals plants. To put this all into context: wWithout plant sex, we humans don't breathe (plants also produce oxygen), we don't eat, and we certainly don't have sex.
EXHIBIT ON DISPLAY NOW AT UCONN'S NATURAL HISTORY MUSEUM
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Mark Smith M.S. Geoscientist email@example.com
Annette Evans Ph.D. Student at the University of Connecticut firstname.lastname@example.org