Curious if your fruit tree is male or female? Or, if other garden plants need mates for reproduction? Let’s explore the three basic groups at work in our gardens
Want lots of pollinators including bees? The secret is to grow a diverse selection of suitable plants.
Male & Female Plants and Flowers
Have you ever seen that popular meme about bell peppers saying you can tell if a pepper is male or female by counting the number of bumps on the bottom? It claims three bumps is male and four bumps is female.
Well, as fun as it sounds, the whole thing is a myth—just another example of click-bait, pseudo science, or someone’s wild imagination.
For starters, fruit is not male or female and it does not reproduce. But plants do, of course—and, depending on the species, there may be male and female plants, or male and female flowers, or flowers with everything all-in-one.
Once you know these basic groups, it’s easier to understand the pollination process and whether your plants may need some pollination partners nearby to produce fruit.
Most flowering plants (angiosperms) are hermaphroditic (90%), which means they have both male and female parts together on each flower. The males have pollen-producing stamens and the females have ovule-producing carpels.
This arrangement is called ‘perfect’ or ‘bisexual’.
“Perfect” sounds self-sufficient and it can be, but there are exceptions.
Hermaphroditic fruit trees are a good example.
Peach and sour cherry trees usually self-pollinate and produce fruit. This is known as ‘self-fruitful’.
Others like blueberries, plums, and apples do best with outside pollination from a different variety of the same species even though they too have ‘perfect’ flowers. These are called ‘self-incompatible’ or ‘self-unfruitful’ or ‘self-sterile’. Growing instructions often recommend having at least two other varieties nearby to help avoid ‘inbreeding depression‘ and reduced fruit set.
What does it mean to have another variety ‘nearby’?
Most sources say within 50 feet is best to increase the odds of animal pollinators or the wind delivering the pollen where it’s needed.
Some other apples, known as triploids including Jonagold and Gravenstein have an extra set of chromosomes making their pollen sterile. This means they can’t serve as pollinators, but they can be pollinated, of course, or they wouldn’t produce apples.
So, it’s not enough to know other apple trees are nearby but they must be pollen providers.
That said, sometimes the options are broader than we might think. Ornamental crab apple trees, which are in the same genus as other apples, are good pollinators for lots of our favorite edible apple trees.
And timing matters: bloom times need to line up so the pollen is available when the recipient flowers are ready for it.
That’s a lot of details, I know.
With so many nuances, it’s always good to check your plant tags to know whether your fruit tree may need some friends nearby and what kind.
It’s usually not an issue in established neighborhoods with older gardens and a wide variety of plant species. But new housing developments with nothing but grass lawn can be pollinator dead zones requiring more intentional plant choices.
Dioecy [Greek: “two households”]
Dioecious plants house their male and female flowers on separate plants. This is most common among gymnosperms—non-flowering seed plants, and less common with flowering plants (5-6% or approximately 15,000 species).
And, just as you’d expect, reproduction for dioecious plants is biparental, meaning it takes a male and a female plant.
One advantage to dioecy is the prevention of inbreeding or self-fertilization.
So how can you tell a male plant from a female? It’s all about the flowers. A Google image search is probably most helpful to see specific examples for each species. Besides different flower components, berries offer another hint. If the dioecious plant is growing berries, it’s female.
Dioecious Plant Examples
Here are some examples we may have in our gardens.
- Japanese knotweed (highly invasive)
- Holly (Ilex species)
- Nettle (gymnosperm)
- Osage orange
- Red cedar
- Red campion
- Skimmia japonica
- White ash
Holly plants can have male or female flowers— but not both—on an individual plant.
The female plant must be pollinated by a nearby male to produce berries (drupes).
Asparagus | It’s often recommended to remove female asparagus plants from a patch because, with some of their energy directed toward berry production, they tend to grow smaller spears. Without this demand, male asparagus plants tend to provide bigger spears. Both, however, are edible.
Monoecious plants can have male and female flowers in separate structures on the same plant.
But this flower arrangement does not mean the plant is always self-fertile. Some monoecious plants are self-infertile (the pollen ripens before the stigma are receptive) and require another cultivar for cross-pollination.
Monoecy is common in conifers, some flowering plants (7%), and some algae.
Monoecious Plant Examples
- Betula species (birch)
- Conifers (most)
- Hazel Corylus avellana
- Zea mays (maize)
Squash | If you’ve ever grown squash you may have noticed that not all of the flowers turn into squash fruit. That’s because some blossoms (on the same plant) are male and some are female. The males often grow first. You can tell the female by the immature fruit bulb at the base of the flower.
Some of us hand-pollinate our squashes to help them along. To do this, pollen is taken from the anther of the male flower and dabbed onto stigma of the female. Once that’s complete, young male flowers can be harvested and eaten, allowing the plant to puts its energy elsewhere. The females will provide your squash harvest.
There is no such thing as male or female fruit but there are male and female plants and plant parts, specifically in the flowers.
Hermaphroditic plants have male and female parts together within the same flower. A majority of flowering plants are hermaphroditic. Roses and lilies are examples. Some hermaphroditic plants are self-fertile (e.g. sour cherry, peach, and plum trees), while others still need pollen from other nearby varieties of the same species to produce fruit (blueberry, apple).
Dioecious plants house their male and female flowers on separate plants. Examples include holly, kiwi, and asparagus.
Monoecious plants can have male and female flowers in separate structures on the same plant. Examples include squash and cucumber.
Get to know what you’re growing and find out what’s recommended for the specific plants in your garden. If you have a fruit tree or shrub with low or no yields, it could just be waiting for some friends to help it along.
- Do Plants Have Gender? | Most plants are hermaphrodite, but not all—and an interesting situation arises when only one sex is imported into the UK | by Ken Thompson | The Telegraph
- Plant Reproduction | Letstalkscience.ca
- The relative and absolute frequencies of angiosperm sexual systems: Dioecy, monoecy, gynodioecy, and an updated online database | Researchgate.net
- Pollination in Lowbush Blueberry | University of Guelph
- Mechanisms That Prevent Self-Pollination | britannica.com
- Crash Course on Plant Reproduction (video)
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