Pollination is a vital part of plant reproduction and it’s essential for a strong, healthy ecosystem. Entomophily, which is pollination by bees and other insects, is the predominant form of pollinating plants. But, as the White House warned in 2014, there have been serious pollinator losses over the past few decades.
Fortunately, there are other methods of pollinating plants including wind and water pollination. Manual or hand pollination is another option. While it can be time-consuming and labor-intensive, research shows that it can reduce or prevent the financial risks of insufficient natural pollination globally.
What is pollination?
Pollination is a biological process in which pollen grains from the male reproductive part (anther) of a flower are transferred to the female reproductive part (stigma) of the same or another flower, leading to fertilization. This process is essential for sexual reproduction in flowering plants (angiosperms) and results in the formation of seeds and fruits.
The process of pollination can occur through various mechanisms. Interestingly, different plants have evolved diverse strategies to attract pollinators, such as bees, butterflies, birds, bats, moths, beetles, and other insects or animals.
These pollinators visit flowers in search of food (nectar or pollen). While they forage, they inadvertently pick up and transfer pollen from one flower to another.
As the U.S. Department of Agriculture (USDA) Forest Service sagely states, “Pollination is an essential ecological survival function.”
But over the past few decades, there has been a significant loss of pollinators, including honey bees, native bees, birds, bats, and butterflies, from the environment. Because of this, the USDA has been tasked with developing management practices to expand pollinator habitat on federal land.
Types of pollination
The two primary types of natural pollination are self-pollination and cross-pollination. And then there is manual pollination carried out by humans.
The type of pollination a plant species relies on depends on various factors, including its flower structure, environmental conditions, and the availability of pollinators in the area. Some plants may be adapted to a specific type of pollination, while others use a combination of methods to ensure successful reproduction and the continuation of their species.
Manual Pollination
Also known as hand pollination or human-assisted pollination, manual pollination involves manually or mechanically applying pollen to flowers. It is or may be used where there are no pollinators or where pollinators are not reliable.
A study published in 2021, states that hand pollination of crops globally is “of major importance.” The findings show that manual pollination is used worldwide on 20 economically important crops. These include some apple trees, oil palms, and cocoa.
Ultimately, even though it is generally time-consuming and labor-intensive, the researchers maintain this method of pollination has many benefits for farmers, including:
- Ensuring constant yields
- Avoiding over- or under-pollination
- Managing the frequency of pollination
- Controlling the origins of pollen
- Choosing the optimal time for pollination to take place
- Preventing or reducing financial losses
Cross-Pollination
Cross-pollination involves the transfer of pollen between flowers on different plants of the same species by the wind, water, or pollinator. This means that it relies on input from an outside source.
There are several subcategories of cross-pollination that are categorized by what achieves the pollination:
- Entomophily – insects including honey bees, butterflies, flies, and beetles.
- Ornithophily – birds
- Chiropterophily – bats
- Anemophily – wind
- Hydrophily – water
Cross-pollination often results in greater genetic diversity and can lead to healthier and more resilient plant populations.
Self Pollination
Some plants can self-pollinate, where the pollen from the male anther of the flower fertilizes the female stigma within the same flower or another flower on the same plant. Self-pollinating plants have evolved mechanisms to promote self-pollination.
They include flowers that incorporate both male and female reproductive organs. These facilitate pollen transfer within the same flower or flowers that are very close to each other on the same plant.
While self-pollination ensures reproductive success when pollinators are scarce, it can result in limited genetic diversity.
Can you pollinate plants without bees or insects?
Apart from manual pollination, self-pollination is carried out without bees or insects to pollinate plants. Some forms of cross-pollination do need bees or insects to move the pollen onto other flowers, but others are executed without bees.
More specifically, neither anemophily nor hydrophily rely on bees, butterflies, or other insects for pollination. Unfortunately, both types are less efficient than insect pollination.
However, they play a major role in many instances where insects are scarce or not available for pollination.
Anemophily: Wind Pollination
Certain plant species have evolved to be wind-pollinated. These plants produce large quantities of lightweight, small, and dry pollen grains that are easily carried by the wind.
Blown by the wind, the pollen is released into the air. It can, though, travel significant distances before it reaches the female flower’s stigma.
This makes wind pollination less targeted and efficient than insect pollination. As a result, wind-pollinated plants tend to produce a larger number of pollen grains to increase the chances of successful pollination.
Hydrophily: Water Pollination
Water pollination is quite rare and is restricted to just a few aquatic or semi-aquatic plants. The male plants release their pollen directly onto the surface of the water, and it gets transported to the female flowers.
How to pollinate plants without the help of bees and insects
The only way to manipulate pollination without the help of bees and other insects is with manual pollination. There are several techniques for hand pollination, some more complicated than others.
Shaking or Tapping
This is the easiest manual pollination method, but it isn’t always successful. It is mostly used for plants that have loose pollen that is easy to disperse.
You need to ensure that the flowers are close enough to allow the pollen to fall on the stigmas of nearby flowers. Then, all you do is gently shake or tap the flowers to release pollen onto the stigma.
Blower or Fan
This method will work if the plants you want to pollinate are normally pollinated by wind. When there is a lack of wind, you can use a gentle blower or fan to blow the pollen from one flower to another.
Just make sure you position or hold the device at a distance that will avoid damaging the flowers. At the same time, you will need to ensure that the pollen is carried by the air currents to nearby flowers.
Professional Hand Pollination
This is the method that is used for plant breeding and in controlled agricultural settings. It is not a method commonly used by home gardeners, though there’s nothing to stop you from experimenting.
Basically, you’re going to copy what happens when bees pollinate. The difference is that bees don’t think about what they’re doing, but you’re going to have to!
First, make sure you know which is the male anther and the female stigma. Then use a small paintbrush or cotton swab to gently collect pollen from the anther.
Transfer the pollen to the stigma of the same flower or another flower of the same species by gently brushing or dabbing the stigma. Then repeat the process for each flower you want to pollinate.
Why should you learn manual pollination?
Manual pollination is invaluable in agricultural settings to ensure consistent and reliable crop production. Manual pollination is also a fundamental technique in plant breeding programs.
It is an essential process for producing hybrid seeds, which are the result of crossing two genetically distinct parent plants. Manual or hand pollination can also help to increase the reproductive success of some rare or endangered plant species.
But, if you are a home gardener, why should you learn about manual pollination? Quite simply, for gardening enthusiasts, manual pollination can be a rewarding and educational hobby.
What plants do not need bees to pollinate?
There are some plants bees don’t need to pollinate. This is because some plants have evolved alternative pollination mechanisms.
We’ve already said that wind-pollinated plants rely on the wind to carry pollen from one flower to another. Examples include some agricultural crops like corn, wheat, and rice, as well as certain conifers and trees that include oaks, pines, and birches.
Similarly, those plants that are pollinated via the water are immune to the need for bees. These include various aquatic plants like water Vallisneria and some water lilies.
Obviously, self-pollinating plants don’t need bees either. Examples include beans, peanuts, some types of orchids, tomato flowers, wheat, and some fruits.
There are also a few self-pollinating fruit-bearing trees that don’t rely on news and other insects for pollination. There are also a few nut-producing trees that rely on wind pollination.
Conclusion
Pollination is vital for plants to reproduce and there is an ongoing threat to pollinators including honey bees. It’s not about honey, but rather the vital role that bees play in transferring pollen from one flower to another.
While there are several ways that flowers are pollinated naturally without bees, the use of manual pollination is increasing in key agricultural sectors. But this form of hand pollination is not limited to scientists, you can try it too … if only just for fun.