How does pollination occur?
If you look all around you in spring and summer and into your garden, you begin to understand the sexual nature of plants and how they propagate themselves. Fertilization comes in a number of ways: insect pollination, wind pollination, and self-pollination.
With self-pollination flowers contain both the male and female parts.
Some flowers that are rich in pollen use attractors like gorgeous colors to lure insects, and some emit ultraviolet rays visible to insects although not to us.
Pollination "is the act of transferring pollen grains from the male anther of a flower to the female stigma. The goal of every living organism, including plants, is to create offspring for the next generation. One of the ways that plants can produce offspring is by making seeds. Seeds contain the genetic information to produce a new plant.
Flowers are the tools that plants use to make their seeds. The basic parts of the flower are shown in the diagram below.
Seeds can only be produced when pollen is transferred between flowers of the same species. A species is defined a population of individuals capable of interbreeding freely with one another but because of geographic, reproductive, or other barriers, they do not interbreed with members of other species."
Self-pollinating plants
So how does pollen transfer take place in self-pollinating plants? Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is transferred to the stigma of the same flower; in geitonogamy, pollen is transferred from the anther of one flower to the stigma of another flower on the same flowering plant.
Self-pollination is seen most often in some legumes such as peanuts. In another legume, soybeans, the flowers open and remain receptive to insect cross pollination during the day. If this is not accomplished, the flowers self-pollinate as they are closing. Among other plants that can self-pollinate are many kinds of orchids, peas, sunflowers.
Male & female flowers and insect pollination
Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Pollinating insects are often just referred to as pollinators. The list of insect pollinators is long and includes many different species of bees, flies, wasps, beetles, butterflies and moths.
How can you tell which flowers are male, and which flowers are female, and why does it matter? In the case of zucchini and other squash plants the male flower grows on a stem, whereas the female flower has a kind of a knob that then grows into a zucchini.
Parts of a Flower
Flowers are the way plants produce seeds to reproduce.
The male parts of the flower are the stamen, with the anther at the top.
The female part of the plant is called the pistil, and the top of the pistil is the stigma, the sticky surface receptive to pollen.
Pollen is produced in the anther, and seeds in the ovary.
1. Don't pick all the male flowers in your garden to use for recipes!
Now that you understand how insect pollination works, it should be clear that without male flowers in your garden, the female flowers will never be pollinated and you won't have zucchini in your garden!
I love deep fried zucchini flowers – and other squash flowers – but you need to pick them judiciously always leaving behind male flowers so that pollination continues to occur.
You might be thinking you won't have enough flowers to cook with, but here's my trick to overcome that obstacle, plus a recipe for deep fried zucchini flowers.
2. Attract pollinators to your garden by planting brightly colored, fragrant flowers in your garden ecosystem
Flowers rely on insects to make the transfer of pollen to fertilize the plant and in exchange insects can eat the sugary liquid that's produced by the tissue at the base of a flower that secretes nectar.
We all love bees – after all they give us honey, which everyone loves.
But bees are not the only pollinators in the insect world. Flies are also great pollinators so you might want to also attract them into your garden.
Beetles are also pollinators. There are more beetles on earth than any other living creature, and the number of species alone is roughly ¼ of 1 million.
Ladybugs are great pollinators. They travel from garden to garden and tree to tree to gather food, which includes pollen and nectar. Vulcan termite says “you can buy a ladybug colony for your garden online or at your local nursery. But [be aware] that buying them doesn’t guarantee that they will like any of the food in your garden, that’s why attracting them naturally is the best way.
Grow flowers and herbs that have white and yellow blooms along with flat leaves. A flat-leaf shape is a perfect place for ladybugs to rest their wings and land for a bit pollinating.
Flowers that attract ladybugs: marigolds, chives, dill, angelica, yarrow, and feverfew.”
Some plants are particular about their pollinator. For example, watermelon mostly depend on honeybees for pollination so a poor bee population in your garden means trouble for your watermelon unless of course you resort to the laborious task of hand pollination. You can hand pollinate simply by using a soft brush and a cotton swab.
Let's take a look at pumpkin plants that have both male and female flowers, just like zucchini.
Generally the first eight flowers produced are male flowers and then about a week after these flowers appear, you begin to see the first female flowers. Flowers don't last long – just a few hours – and they bloom at dawn and generally close before noon. Pumpkin plants have to be pollinated by insects and heavy pollinator activity will increase both the number of pumpkins and their quality.
3. When you plant your garden, think about the entire ecosystem and not just the plant you are putting into the ground.
You need to think about your insect population, and the right insects for what you plant in your garden. As mentioned above some plants emit ultraviolet light, not visible to the human eye, but are a great attractor for insects. Insect pollinated flowers often have an enticing scent and large and colorful petals, nectar, and often sticky hooked pollen, to make sure there is proper transfer of the pollen.
4. Find out which pollinators your garden plants like best, and make sure you add some of the flowers that attract those pollinators to your garden ecosystem.
Sometimes pollination might not be important for some of your garden plants
You may have plants in your garden like spinach or kale that you plant just to harvest the leaves.
If you start harvesting only the top ⅔ of your spinach plant and then let the plant continue to grow, about half of the spinach plants (male) will produce tiny yellow flowers that only make pollen. The other half of the plants (female) produce lots of green lumpy balls on the plant that eventually turn into seeds. After the seeds turn brown, take them off the plant right away and surprise surprise! You'll have a second planting of spinach and also enough seeds to plant spinach the following year.
Wind pollinated plants
5. Plant corn in a grid, never in a single row
When you plant a wind pollinated plant like corn pay close attention to how you do your planting. Instead of insects it's the wind that carries the pollen from plant to plant and if you don't plant your corn properly, you'll find your ears of corn are missing lots of kernels. When you have an ear of corn missing a lot of kernels that simply means the plant has not had proper pollination. This usually occurs because the corn has been planted in a row instead of a grid of 3 x 3, or 4 x 4, in other words, a square. When you have corn growing in a square when the wind moves the pollen around, it's much more likely that it will pollinate more thoroughly.
How does corn pollination work?
Each individual silk of corn corresponds to one individual corn kernel, so for proper pollination each strand of silk has to be fertilized. When you have plants growing in a square, the likelihood of all strands of silk being pollinated is much higher.
All wind pollinated plants behave this way: beets, spinach, and Swiss chard. But again since pollination's only necessary to produce fruit and seeds when you're growing a plant to eat the leaves, it's not usually a concern.
Have you ever cooked with wild spinach, better known as lambsquarter? We often go foraging in the woods near our home in search of wild asparagus and wild spinach. Here's what it looks like, plus a recipe.
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Mary DiPietro Johnson says
Sacramento, California with roots in Abruzzo. Listening to Michelle on this episode makes me think she would quickly succumb to the wonder and pleasure of fig propagation.
Mary DiPietro Johnson
Wendy says
Mary, since you have the same last name as Michelle, maybe you are related?! You, like I, are in an amazing fig climate, but the northeast United States is not ideal.
I have lots of foodie friends who live in Sacramento!
Mary says
Fabulous. Now I need an episode or two on figs. The quest for Italian varieties in the US, propagation, folklore, and taste profiles, and the sheer wonder of them all.
Wendy says
Mary, thanks for the great idea! I love suggestions from readers and listeners and I agree a fig episode would be perfect. May I ask where you are from?