Dioecious And Monoecious Information – Learn About Monoecious And Dioecious Plants


By: Mary Ellen Ellis

To take your green thumb to the next level, you really need to understand the biology of plants and the botanical terms that describe plant growth, reproduction, and other aspects of plant life. Get started here with some dioecious and monoecious information that will have you impressing your gardening friends.

What Do Dioecious and Monoecious Mean?

These are some high-level botany terms. They actually have simple meanings, but if you start throwing these words around at your next garden club meeting, you’ll leave everyone assuming you have a Ph.D. in botany.

A monoecious plant is one that has male and female flowers on the same plant, or that has flowers on every plant that contain both male and female reproductive components. A dioecious plant has either male or female flowers, not both. For dioecious plants to reproduce, a male plant must be near a female plant so that pollinators can do their work.

Monoecious Plant Types and Examples

The banana is an example of a monoecious plant with male and female flowers. The plant develops one large inflorescence that has rows of male and female flowers.

Squash is another example. Only about half of the blooms you get on a squash plant will develop fruit because only half are female.

Many of the plants in your garden are monoecious with perfect flowers, those with male and female parts in the same flower. For example, lilies are monoecious, perfect plants.

Examples of Dioecious Plants

A common example of a dioecious plant is holly. Holly plants are either male or female. On the male plant you will see flowers with the anther, and on the female plant are flowers with the pistil—the stigma, style, and ovary.

The ginkgo tree is another example of a dioecious plant. In terms of gardening, getting dioecious plants to fruit may require more planning. So, if you want to see the pretty red holly berries, you need a male and a female plant.

On the other hand, gardening with dioecious plants can give you more options. For instance, asparagus is dioecious, and male plants are more popular to grow. Because they don’t put energy into producing fruit, you get larger, cleaner spears. With ginkgo, you may choose a male tree only so that you don’t get messy fruit litter on the ground.

Understanding the difference between monoecious and dioecious plants and knowing how to use the terms is not only a great party trick, but it can really help you make better choices in the garden.

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Understanding Flowering Habits In Cucumbers

» Cucumber varieties are either monoecious or gynoecious in their flowering patterns.
» Gynoecious varieties produce only female flowers and have a more concentrated period of fruit production.
» There are also parthenocarpic varieties that do not need to be pollinated to produce fruit.

Cucumbers, like most cucurbit plants, produce separate male and female flowers on the same plant (Figure 1). In botanical terms, these plants are said to be monoecious (translation, one-house). On monoecious plants, the male flowers contain stamens that produce pollen, while female flowers have pistils that contain the ovule. By contrast, plants, such as tomatoes and beans, produce “perfect” flowers that have both male and female parts present in the same flower.

Figure 1. Male (left) and female (right) cucumber flowers.

Both male and female structures need to be present so that the pollen from the male flowers can fertilize the ovules in the female flowers to produce viable seed. Cucumber pollen is produced in a sticky mass and is not windblown. Hence, pollination requires the activity of insects that move pollen from male to female flowers, with bees being the most common pollinators. Once pollen has been deposited on the female flower, the pollen grains germinate and grow down the pollen-tubes to reach the ovules, where fertilization takes place.

As the fertilized ovules develop, hormones are released that stimulate the division and expansion of fruit cells. The development of cucumber fruit usually depends on the presence of an adequate number of fertilized seed within the developing fruit. Without enough fertilized seed, the fruit either aborts or becomes misshapen (Figure 2). 1

Figure 2. Inadequate pollination results in fruit abortion or the formation of misshapen fruit.

While wild-type cucumbers and older cucumber varieties are monoecious, cucumber varieties today can have flowering patterns that are monoecious or gynoecious. In this context, the term monoecious refers to having both male and female flowers on the same plant in about equal numbers. Gynoecious cucumber plants, however, produce only female flowers. A cucumber plant that produces mostly female flowers but a few male flowers is called predominantly female, often designated as PF.

MONOECIOUS CUCUMBERS

Most older varieties of cucumber are monoecious, often producing more male than female flowers. The male flowers typically develop on the main stem earlier and in larger numbers than female flowers. 2 This may be concerning to some, as the plants appear to be only producing male flowers, but the female flowers will start to develop a little later, so that when they are ready to be pollinated, viable pollen will already be present.

Environmental factors can affect the proportion of male to female flowers. 1 For example, plant density can affect the number of female flowers. At higher densities, plants compete for water, nutrients, and sunlight, and the resulting stress can lead to a higher proportion of male flowers. Optimum populations for hand-picked slicing cucumbers are in the range of 24,000 to 26,000 plants per acre. A range of 26,000 to 30,000 plants per acre is recommended for handpicked pickling cucumbers and a range of 45,000 to 65,000 for machine-harvested pickling cucumber. Other stresses, such as damage from insects or blowing soil, low light intensities, or water stress, can result in the production of fewer female flowers. 1 The proportion of male to female flowers is also influenced by temperature, with higher temperatures (86°F and above) promoting maleness and lower temperatures (60°F and below) promoting femaleness. At low temperatures, there may not be enough male flowers to adequately pollinate the crop, while at high temperatures, there may not be enough female flowers to produce the desired number of fruit.

GYNOECIOUS CUCUMBERS

Many modern cucumber hybrids are gynoecious. 2 Gynoecious varieties produce large numbers of female flowers and have a fairly concentrated flowering period. Thus, they produce a lot of fruit over a relatively short amount of time. This concentrated fruit production works well in mechanical harvest systems that harvest only once or in multi pick systems with small harvest windows or the need to rotate to another crop quickly. In contrast, the flowering periods of monoecious varieties are usually more spread-out. Over the course of the season, monoecious varieties will produce about the same number of fruit per plant, but the fruit production will occur over a longer time period and require several pickings. This extended fruiting period may work better for growers who desire sustained production over a longer period to supply sales at farmer’s markets or home gardens.

The female flowers of gynoecious varieties still need to be fertilized with pollen from male flowers, so a certain percentage of monoecious plants need to be planted along with the gynoecious plants to serve as pollenizers. Most seed companies provide cucumber seed blends that contain 85% to 90% gynoecious seed and 10% to 15% monoecious seed. These blends ensure that the optimal proportion of male to female flowers are present in a planting, resulting in good pollination levels and high fruit yields.

PARTHENOCARPIC CUCUMBERS

In addition to gynoecious and monoecious varieties, there is also a third type of cucumber variety, parthenocarpic varieties. Unlike the gynoecious and monoecious varieties, which require pollination to produce fruit, parthenocarpic varieties produce fruit without the need for pollination.

Parthenocarpic varieties are seedless, or nearly so (Figure 3), and the fruit develops in the absence of fertilized seed. These varieties can produce seed if pollinated. Therefore, parthenocarpic varieties should be spatially isolated from other types of cucumbers to keep the fruit seedless. 3

Figure 3. Fruit from seeded (left) and seedless (right) cucumbers. Parthenocarpic cucumbers are used to produce seedless fruit.

Because parthenocarpic varieties do not produce large numbers of seed, even when pollinated, the cost of seed production is high, and the seed of these varieties is typically more expensive than the seed of other varieties. 4

SOURCES

1 Schultheis, J., Averre, C., Boyette, M., Estes, E., Holmes, G., Monks, D., and Sorensen, K. 2016. Commercial production of pickling and slicing cucumbers in North Carolina. North Carolina State Cooperative Extension. AG-552.
2 Orzolek, D., Kime, L., Bogash, S., and Harpe, J. 2010. Cucumber production. Penn State Extension. Agricultural Alternatives. UA463.
3 Wyenandt, A., Kuhar, T., Hamilton, G., VenGessel, M., and Sanchez, E. 2016-2017 Mid-Atlantic commercial vegetable production recommendations.
4 Fanourakis, N., and Tzifaki, E. 1992. Some relationships of seed production with parthenocarpy and relative humidity in the cucumber. Cucurbit Genetics Cooperative Report 15:11-12.

ADDITIONAL INFORMATION

For additional agronomic information, please contact your local seed representative. Developed in partnership with Technology, Development & Agronomy by Monsanto.

Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about cucumber production. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, pathologist and similar professional dealing with this specific crop.

SEMINIS DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE. 161028154925 042717DME


Botanical Terminology: Flowers, Houses and Sexual Reproduction

Monoecious and Dioecious - What language is this? These botanical terms sound like a description of some kind of tempting dessert. Actually, these are terms used to describe the reproductive behavior of some plants. Not all plants have perfect flowers. "Perfect" in a botanical sense means that each flower has both male and female parts in the same structure. Lilies, roses, and apple flowers are perfect.

Before you decide that this topic is too technical for you - just wait! You like squash, right? You want pretty holly berries in your landscape, right? These are plants where the difference between "monoecious" and "dioecious" matters.

Monoecious plants have male flowers and female flowers in separate structures on the same plant. "Mono" means one - and the term "monoecious" is literally "one house". The same plant houses different flowers, some being male the others being female. Squash is monoecious. If you take a close look at squash flowers you can soon tell which are female because they have a tiny fruit at the base. For obvious reasons, the male flowers don't. Knowing that only the female flowers produce fruit and that only 50% of the flowers on squash are female can save some heartache when all the flowers on the plant don't produce fruit.

Dioecious plants house the male and female flowers on different plants. So not only does the plant have separate male/female flowers, they have male plants (with only male flowers) and female plants (with only female flowers). Hollies and asparagus are dioecious. Since only the female plants can produce the fruit, hollies must have a male plant and a female plant in close proximity. Male holly plants are often given masculine names like 'Southern Gentleman', 'Jim Dandy', or 'Blue Prince', so they are easy to recognize. In the landscape, one or two male hollies are often tucked behind the female hollies to ensure pollination and fruit set and to hide the male plants that don't produce the showy fruit.

The male cultivars of asparagus are more popular with gardeners than the females. This is because the male spears are larger, they don't waste any effort on fruit production. Male plants can also be neater. Male ash trees don't produce the "canoe paddle-like" fruits like the females. Male trees of Kentucky Coffeetree, Cork Tree, and Ginkgo are popular for the same reason - no messy fruit!

So knowing the difference between plants with perfect, monoecious, and dioecious flowers can be important when gardening. It also can make you sound like a gardening expert - try dropping "monoecious" on your guests at your next dinner party. If you are serving squash, it should be easy to explain!


What are Imperfect Flowers?

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Imperfect flowers are flowers that only have one set of reproductive organs, so they are considered to be either male or female. Flowering plants can fall into two categories of imperfect flowers: monoecious or dioecious. The first occurs when a plant has some flowers that contain only the pistil, or female reproductive part of the flower, while other flowers on the same plant only contain stamens, the male reproductive part of the flower self-fertilization is possible with monoecious plants, and pollination can also occur by other sources such as the wind or insects. Dioecious plants, on the other hand, are made up of flowers that are either male or female as a result, male and female versions of the plant must exist near each other in order for pollination to happen at the hand of outside sources.

Categories of Reproduction

All flowers fall into one of three categories of reproduction: perfect, imperfect, or incomplete. Perfect flowers, such as roses, are flowers that contain both a pistil and stamens, and therefore are both male and female. Imperfect flowers are either male or female, and a plant can contain male or female flowers, or both. The incomplete flower can be either perfect or imperfect, but is missing one of the four major parts of a flower: the pistil, stamens, petals, or sepals. If a flower is unable to reproduce on its own, pollination can occur to allow for fertilization and reproduction to take place.

Pollination

The process by which plants reproduce is known as pollination during this process, pollen containing sperm from the male flower is transferred to the female flower, which typically results in new life. While perfect flowers can reproduce entirely within one bloom, imperfect flowers need two separate flowers, a male and a female, in order to pollinate and create seeds. When both organs are not present on flowers of the same plant, a plant of the opposite sex must live nearby for pollination to happen. Pollen can be transferred by animals, insects, weather, or humans, but an imperfect flower will usually need some sort of outside facilitation in order to reproduce.

Monoecious and Dioecious

Imperfect flowers grow on one of two types of plants, monoecious or dioecious. Monoecious plants have both male and female flowers, while dioecious plants are either male or female. As opposed to the moneocious plant, which contains both sexes in close enough proximity to self-fertilize, the dioecious version requires that a plant of the opposite sex reside close enough for pollination to take place. In this instance, there typically needs to be intervention by outside sources, such as insects, in order to pollinate the female flowers. Some horticulturists consider imperfect flowers to be more difficult to cultivate, due to the inability of the dioecious plant to self-fertilize. Common examples of an imperfect flower that is monoecious are corn, birch trees, and walnut trees, while common dioecious plants include holly, willow trees, and poplar trees.


Watch the video: Bio group project- Monoecious vs dioecious plants


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