Show Me Oz – No matter where you live in the country, you are either itching to get your hands in the dirt or are already in the garden digging, planting and dreaming! If you want to save seed this year, you have come to the right place! Because today we are talking about flowers and how they achieve pollination – and what those two things have to do with saving pure quality seed. Understanding these things not only helps you reap a larger harvest of fruits and vegetables to eat, but also ensures that the seeds you harvest from those fruits will come true in next year’s garden. So, let’s get right to it!
When is the Best Time to Start Saving Seed?
The very best time to start saving seed is before sowing or transplanting to the garden. Begin by learning about the plants in the garden, how they are related to one another, and how they use their flowers to produce both seed and fruit. The very first thing any seed saver should do is write down the botanical names of the plants we plan on having in our gardens.
I like to write this name right on the seed packets for quick reference. Knowing the botanical names of plants is critical to saving seed that will grow into offspring that are exactly like the parent plants from which they came. If you need a refresher on what are referred to as the scientific, Latin, or botanical names of garden plants, you might want to check out my article, Seed Saving Time: What’s in a Name?.
If this is your first time saving seeds, you might also like to read the following articles, which will help explain the difference between open pollinated, heirloom, GMO and hybrid seeds.
Of course, if you’d like to learn all about how to save your own seed in plain English, check out my book, The Garden Seed Saving Guide!
What is Pollination?
Pollination is essentially a method by which plants sexually reproduce. Without pollination, plants will not produce fruit. During pollination, pollen from the anther of a male flower or flower part is transferred to the stigma of a female flower or flower part. Once the stigma has been inoculated, a pollen tube grows down through the style and to the ovary where one or more ovules are fertilized. Once fertilized, the ovary begins to swell and ultimately, becomes the fruit we eat.
As the fruit matures, the fertilized ovules ripen into seeds. When the seeds are mature, each will contain the germ (or embryo) of a new plant that will carry the various genetic traits inherited from both of its parents. Only fully ripe fruits bear mature seeds.
Pollination is typically achieved through the actions of wind, rain, animals or insects that physically move pollen from one flower to another, but certain types of flowers have the ability to pollinate themselves.
The term cross-pollination is often defined as the movement of pollen from one flower to another regardless of whether it is natural or mechanical. Natural cross pollination (NCP) refers only to the natural process of pollination and does not include forced pollination (hand pollinating) or genetic manipulation. Self-pollination (selfing) occurs when pollination occurs within a single perfect flower that contains both male and female reproductive organs (stigma and style). Nature only allows cross-pollination between varieties of the same species and natural cross-pollination occurs frequently in nature. We’ll talk more about that in a minute.
For now, just keep in mind that pollination is not required to reap the fruits of crops in which the edible portions are produced underground – includes garden crops such as potatoes, onions, garlic and sweet potatoes, among others. Tubers, bulbs and cloves are not fruits, but a type of storage root. Also, pollination is not required to obtain the edible portion of vegetative crops such as asparagus, lettuce, cabbage, and so on. But it is required to obtain viable seeds of these crops.
How Plants Use Flowers in Pollination
Although pollination is the physical act of reproduction, it is the arrangement of sexual organs within a flower that determines how reproduction occurs. There are many ways that flowers present their reproductive organs and knowing the basics of these mechanics is crucial to saving pure seed. For, while flowers are beautiful to look at, their sole purpose is to propagate the species.
All flowers are made up of several parts, the most noticeable being showy petals and sepals. The shape, color and scent of these flower parts are designed to attract specific pollinators like bees, butterflies and moths. Some flower petals even act as pollinator landing pads that direct the insects deep into the heart of the flower where the sexual organs are located.
Stamens are the male sexual reproductive organs. Stamens consist of a thin filament that supports the anther, which produces pollen. Pistils are the female sexual organs. Each pistil is made up of a stigma, style and ovary. The ovary is essentially the womb of the plant where fertilized ovules grow into seeds. In the case of vegetable crops, the ovary is also the portion of the plant that becomes the fruit we eat.
For the home gardener, it is important to know two things about flowers:
The first is that each flower can be male, female or bisexual.
The second is how pollination physically occurs.
Some flowers need wind or insects to move pollen, while others require neither. Some flowers pollinate themselves before opening, while others will only accept pollen from flowers on a separate plant. Every seed saver understands that the seemingly elementary process of sexual reproduction in plants is never as simple as we might like it to be. But by knowing if your plants have either perfect or imperfect flowers will help you decide which varieties you can plant closely and which you have to space apart in order to either achieve or prevent natural cross pollination between varieties of the same species.
The Role of Perfect Flowers
Perfect flowers are sometimes referred to as complete or bisexual flowers because each individual flower on the plant contains both male and female reproductive organs. Plants with perfect flowers are often referred to as inbreeders. Plants with perfect flowers include all members of the legume and nightshade families, such as tomatoes, eggplants, beans and peas.
Most perfect flowers have petals or sepals that close around the reproductive organs to protect them from outside pollination – at least for a short time. These flowers can and often do pollinate themselves. But there are exceptions:
First of all, the range of pollination in perfect flowers goes from strongly self-pollinating to strongly cross-pollinating. Let me explain:
In some perfect flowers the pistil will not accept pollen from a stamen within its own flower, but will accept the pollen from a stigma of different flower on the same or different plant. Another example would be when the male and female reproductive organs within a perfect flower do not mature at the same time. Both of these types of perfect flowers are known as self-incompatible and require the pollen of another flower on the same or different plant of the same species to complete fertilization.
Recent studies have shown that cucumbers, which were once thought to be strongly self-pollinating, are actually pollinated by insects over 50% of the time. This fact would place them squarely in the center of the self-pollinating range for perfect flowers.
The Role of Imperfect Flowers
Imperfect flowers are also known as incomplete or unisexual flowers because they contain only one sexual reproductive organ per flower. Basically, an imperfect flower is either male or female. Imperfect flowers need at least one flower of the opposite sex to complete pollination, which is almost exclusively completed by insects, animals, humans or wind. Because of the need for moving pollen between different flowers or even different plants, plants with separate male and female flowers are known as out-crossers.
To complicate things a bit, there are basically two types of plants that have incomplete flowers.
The first are plants that have both male and female flowers on the same plant, such as squash, watermelon, and cantaloupe. These plants are also referred to as monoecious plants.
The second are plants that have either all male or all female flowers on one plant. In other words, the plant itself is either male or female. These are known as dioecious plants. Examples of dioecious plants include spinach and asparagus. In order to achieve pollination, dioecious plants must have at least one male plant of the same species growing near one or more female plants. Without a male plant, the female plants cannot produce fruit or seed.
Knowing how flowers achieve pollination is critically important to the success of the seed saver. By understanding the mechanics behind how each crop is fertilized the seed saver can take steps to manage that process in a way that prevents unwanted natural cross-pollination between two or more varieties of the same species through the use of common isolation methods, which we’ll talk about next time, right here at Show Me Oz!
Until then, happy gardening!
© 2016 Jill Henderson Feel free to share with a link back to the original article.
Save money, become more self-sufficient and avoid GMO’s by saving seeds! This excellent resource for beginning and hobby seed savers takes you step-by-step through every aspect of saving your own seed in plain English.
Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore. Jill is a contributing author for Acres USA and Llewellyn’s Herbal Almanac and her work has appeared in The Permaculture Activist and The Essential Herbal.