Trees with seeds and fruit have their benefits - and problems - that go along with them. Luckily, there are so many options available these days that it can be confusing when hearing all the various terminology that goes with plant options.
So what’s the difference between all these new types of trees and shrubs?
In the world of plants - anything goes! Ma Nature regularly makes up rules, breaks them, remakes them, and then changes her mind once again. So plants have every possibility of reproduction available because of how ‘stuck’ in one place they are! So they of course had to get creative!
Monoecious plants have separate male flowers and female flowers on the same plant. The term "monoecious" is literally "one house". Squash for example has male flowers and female flowers on the same plant.
These plants have male on one plant, and female flowers on another. Some Holly, Ash trees, Kentucky Coffeetrees, and Ginkgo trees are good examples. You need a male plant nearby to pollinate your female plants in order to see any fruit on the female plants.
Hermaphroditic flowers have both male and female structures within each individual flower, which are known as ‘perfect’. Each bloom can potentially pollinate itself without another flower. Bees or insects help distribute the pollen, and sometimes even wind.
Perfect flowers can either be self-fertile or cross-pollinated. Cross-pollination needs another of the same plant nearby, or a slightly different variation of that plant. For instance, a Royal Ann Cherry Tree needs a Van, Stella, or a Black Tartarian Cherry tree nearby to pollinate it and set fruit. Bees are happy to visit both flowers and pollination occurs.
Ma Nature's curveball - In a process called agamospermy, a plant egg can mature into a seed without being pollinated at all! The offspring is genetically identical to the parent plant.
Sterile and seedless plants are hybrid cultivars that have been bred not to produce seed at all. This creates a triploid, like seedless watermelons and seedless grapes for instance. The genetics have been tweaked within these plants to make them entirely seedless or sterile.
A normal diploid (like you and I) has two complete sets of chromosomes - one from each parent. White a triploid plant has three sets of chromosomes and retains many desirable characteristics, including increased vigor; larger flowers, or a larger fruit set.
Then there are Triploids or Polyploidy, which as the name suggests, have three or more sets of chromosomes.
Seedless watermelons are triploid which causes them to be seedless. These seeds are created by crossing a normal diploid as the pollinator with a tetraploid (Four sets of chromosomes) parent. Each parent contributes half its respective chromosomes, resulting in one from the diploid parent and two from the tetraploid parent. Sounds confusing but luckily the scientists have it all figured out and you don’t have to worry about seeds while munching on your favorite summertime fruit!
Some plants and animals are bred (or have genetic abnormalities) and can become Polyploids that contain three, five, or some other odd number of chromosomes.
A sterile perennial Geranium we love is Rozanne, which tries so hard to produce seed that it simply keeps on producing flowers all season long in that quest of trying to make seed.
Then there are flowers like those on the Avocado tree which are perfect flowers, but they don’t function at the same time! The flowers are either male or female in the morning and then become the opposite later on or the next day. This means Avocado trees require a Type A and Type B tree planted in close proximity to increase pollination chances.
The Giant Amazon Water Lily (Victoria amazonica) is another unusual perfect flower that has evolved a unique process of pollinating itself. Called co-sexual, the flowers open white in the evening, and are fragrant and warmer (called thermogenesis) than the surrounding male flowers. These close for the night trapping insects inside. In the morning, the flowers become female and open, and pollen gets distributed while the insect searches for a way out. Finally, the beetle is released to find another flower and gets trapped to start it all over again.
Other plants can even change their sex based on the availability of other plants in the area, or based on their age and their height/sun availability.
Lastly, plants like non-flowering Mosses, Liverworts, Hornworts, Lycophytes, and Ferns dispense with flowers entirely and reproduce by spores.
There are always upsides and downsides to everything, and toying with the genetics of plants has come under scrutiny these days. Plausible, because everything in our environment does eventually affect us.
So let's break down the pros and cons of all these types of plants!
By planting trees, shrubs, and plants with perfect flowers, or a female plant with a male nearby, you then enjoy nuts, seeds, and fruit! When this comes to the perfect flowers of our favorite fruit trees like Grain, Nut trees, Apples, Pears, most Berries, and Grapes; having fruit is a great thing! Most of the world is fed on these wonderful plants! Fruit and seeds of these plants also feed birds and other wildlife.
But these fruits do have seeds and those seeds do want to grow. Good if you are propagating and expanding your garden, but bad when those seeds come up everywhere and get into trouble. Like some plants that have become invasive in some areas.
If we don't want the fruit or seeds of the plants that produce them, there are some other options to consider. Trees that are not as messy are perfect for more urban landscapes.
Male-only trees solve the problem with fruit drop and seed dispersal. No fruit means clean driveways and patios, no stains on sidewalks and deck furniture, and you don’t have to worry about birds eating the fruit and spreading their droppings and those seeds far and wide. Planting male trees or sterile trees near your home means not having the mess in your gutters, or having to rake up the mess beneath. These plants are also not considered invasives in any area.
The problem with male-only trees though, is that they still produce flowers - flowers chock full of pollen! Great for Bees and pollen-eating insects, but bad for our noses! Those who suffer from allergies are noticing an increase in their symptoms and increased frequency of pollen-related issues now that there are more male trees in the neighborhood!
From an environmental aspect, having sterile plants reduces the chances of spreading invasive plants around where they are not native, and choking out local flora. Not necessarily meaning fruitless, it simply means the fruit won’t have viable seeds or any seeds at all. In fact, food harvest and fruit size can be increased in sterile plants. Plus, sterile plants can be shipped into areas where their seeded versions cannot due to invasive concerns.
However, by planting these in areas they are not indigenous, and local pollinators and native insects often don’t recognize them as a food source. Good if you are trying to reduce pest damage, bad if you are trying to feed the bees, butterflies, and their larvae. Also having sterile plants means your feathered friends go hungry.
Most of the issue with sterile plants that won’t produce fruit comes from those who think that changing the genetic structure of these plants (especially those we eat) will ultimately result in changes to our own DNA. While this may seem like woo-woo science, the increase in cancers, behavioral disorders, and the increase in general health issues around the world may just give you some new, literal, food for thought. Remember too that many selections of plants are simply crosses of 2 different plants, or naturally occuring in nature and they are not genetically modified.
The other concern is food sustainability and maintaining native plants and landscape cultivars. With reduced genetic diversity and the ability to save seeds for planting next year, having a landscape full of sterile plants leaves us hanging should they die. Entire crops can be taken out with no way of replacing them with their seeds.
So there’s the good, the bad, and the ugly side to plant gender and how it affects us and our environment. There are benefits and worries to all sides of bringing new and exciting plants to every corner and environment in the US.
So take a look at your options and see what is available before making a decision when landscaping. Alternatives are increasingly easier to find! Look into more careful site selection and your personal needs when choosing plants for your landscape!
Cheap prices, massed produced crops, and pretty faces have hidden downsides lurking in their roots, so educate yourself before buying! As always Nature Hills is here to help with our knowledgeable staff, informative #ProPlantTips and Garden Blog, and our innovative ecosystem protecting Plant Sentry™ that ensures compliance with all Federal Agricultural laws and regulations concerning the shipment of plants from Nature Hills in 48 states.
We are committed to protecting you and your landscape with quality-grown plants that set your garden apart from the rest while ensuring it's safe for all!