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scientists studying hybrid plants

Quick Facts about Hybrid, Heirloom, and GMO Plants

What's the difference between open-pollinated, hybrid, GMO, and heirloom seeds? Do hybrid varieties outperform heirlooms? Do heirlooms produce tastier fruits and vegetables? Are hybrids the same thing as genetically-modified organisms (GMOs)? Are there frog genetics in my tomatoes? These questions come up from time to time in the gardening groups and forums we follow, and in conversation when we shoot the breeze with customers who contact us for orders or questions

We encounter these questions from beginners and experienced gardeners alike, so we decided to tackle the topic here on our gardening blog. We'll start with this: The main differences between the three are the method by which they're "bred," and how their genes are carried through generations. Now, on to the specifics: 

What is open pollination? 

Open pollination is how plants naturally reproduce. Wind, insects, birds, and mammals distribute pollen to plants of the same species, or to those related closely enough to breed. Sometimes, open pollination creates new varieties of a species. 

Horticulturists define open-pollinated plants (OPs) as producing "true to type" offspring, and these species are often referred to as "standards." Some OP plants can pollinate themselves, and these offspring most closely breed "true" as their genetics remain consistent. 

What are hybrid plants? 

Hybrids are crosses of two separate species within a genus. The resulting offspring (F1 generation, in science-y terms) exhibit characteristics of each parent, and these similarities are consistent each time the two parents reproduce. The offspring plants themselves do not reproduce true-to-type and are often sterile. A familiar example from the animal world is the mule (Equus asinus × Equus caballus), which we all know is a hybrid between a horse (Equus caballus) and a donkey (Equus asinus). These two animals can breed without human interference.

How to hybridize plants

In horticulture, seed producers and hobbyists create hybridized seeds by manually removing pollen from one plant and fertilizing another, and then saving the resulting seeds. Another method is growing parent stock from each species in close proximity but isolated from plants that may cause unwanted pollination.

Those who are the first to "invent" a plant asexually (by hand-pollination) may patent the cross. There are limitations on the types of plants that qualify for patents, but those who hold them are entitled to sue others for replicating the process. Learn more about legislation protecting rights to ownership of plant hybrids in the 1970 Plant Variety Protection Act and amendments to the 2018 Farm Bill

Naturally-occurring hybrids do exist

Peppermint is a natural hybrid of water mint (Mentha aquatica) and spearmint (Mentha spicata). It's also been artificially cultivated since the 18th century, but the plants themselves can't reproduce. If you want to keep your peppermint patch growing true to type, you can do so from cuttings made from F1 plants. 

It's difficult to create hybrids outside of a controlled environment

The clementine is a seedless and easy-to-peel mandarin orange hybrid grown in California. Its parents, a variant of standard mandarins (Citrus reticulata) and a sweet orange (Citrus sinensis "deliciosa")

Unfortunately, parent stock blooms shortly after almonds, which require honeybees for pollination. And hundreds of thousands of honey bee colonies are brought into the state from all over the country for the job. When the almond bloom is complete, commercial beekeepers stick around to get colonies ready for the trip home, and if you drive through central California, you'll see pallets of honeybees here and there in fields. Honeybees can fly up to five miles to find food, and they feed on citrus nectar. Thus, cross-pollinating mandarins with their own or unwanted varieties. 

This has been a big hoo-haw since the mid-2000s when mandarin producers tried to sue beekeepers and make laws to keep the bees from "trespassing" on their orchards. In the meantime, they covered their breeding stock with netting.

What are heirloom plants? 

Heirloom plants are varieties whose genetics have been preserved over generations through seed saving. Farmers and gardeners would select seeds from the healthiest plants in that year's crops to regrow the following season. Before the middle of the 20th century — most specifically before the rise of industrial agriculture after World War II — these were just called "plants." Now, we call them "heirlooms." 

Horticulturists continue to bicker over how long a variety's been cultivated before it can claim the "heirloom" name, but to most of us, heirloom plants are open-pollinated varieties selected for flavor, color, hardiness, and size.  

Why are heirloom plants important?

Heirloom plants play an important role in our ecosystem and food supply. The more genetic variation within plant species, the less likely any one type of staple food—corn, beans, wheat, brassicas—could be wiped out by disease or shifts in regional climates. It's kinda why we don't let first cousins get hitched, especially if they're genetically predisposed to disease or deformities. With plants, over time, specimens exhibiting disease and poor growth are eliminated. In the case of humans, we present to you, "The Darwin Awards."

Home gardeners and small-scale farmers help maintain biodiversity, food security, and cultural traditions by growing heirloom plants and harvesting fresh and robust ornamental, vegetable, and fruit seeds for future generations.

What's the definition of a GMO? 

A plant scientifically and legally classified as a genetically modified organism (GMO) has had its DNA altered in a laboratory setting, using crosses that could never reproduce in nature. Other terms for GMO technology include transgenics, gene editing, and gene splicing. Unlike hybridization, which is often done under sterile conditions, genetic "splicing" transfers genes from one distantly-related species (or completely separate family) to another using mechanical, viral, and bacterial "invasions" of a plant's genetic code. Harvard University posted a good explanation with infographics in "How to Make a GMO."

GMO plants in science lab

Some pro-GMO websites use the "all plants are genetically modified due to trait selection and traditional hybridization, as we're selecting for genetic traits." Technically (but not scientifically speaking), they're correct. But there's a lot of apprehension about combining the DNA of unrelated organisms. 

Availability of GMO seeds

We, like most seed suppliers to home gardeners and North American small-scale farmers, don't carry GMO seeds. Personal opinions aside, in the United States they're only available in industrial-scale crops grown for commodity markets:

  • apple
  • soybean
  • cotton
  • maize
  • canola
  • alfalfa (for animal feed)
  • sugar beet (for granular sugar; the pulp is often used for animal feed)
  • papaya
  • tobacco
  • flax
  • plum

The debate over GMOs

The Pew Research Center's polls indicate that consumers aren't as passionately polarized on the GMO issue as many of us would believe, but enough of the population rejects GMO products to influence marketing and labeling. Those who are wary of (or staunchly opposed to) GMOs share the following concerns: 

  • GMOs may throw ecologies out of balance
  • GMOs may cause new and dangerous food allergies and pathogens.
  • The megacorporations that develop and market GMO seeds will control our food supply.
  • We don't know enough about the long-term health effects of GMO food.

The following are organizations that support genetically engineered plants, or at least consider them a safe solution for improving world health and food security: 

  • Cornell's Alliance for Science counters what they refer to as "myths" about GMO plants. Here's a look at their donors, the largest of which is the Bill and Melinda Gates Foundation. 
  • The National Academies of Sciences, Engineering, and Medicine's verdict on GMO crops is "not guilty" of posing a health hazard
  • According to an extensive GMO factsheet published by the World Health Organization, "GM foods currently available on the international market have passed safety assessments and are not likely to present risks for human health. Also, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved." The WHO also stresses that GMO species must be evaluated on a case-by-case basis before they're approved for use. 

Those who support genetically engineered seed production argue that gene editing's benefits far outweigh any risks, none of which they claim have emerged in the two decades GMO plants have been in production. They point to the ability to quickly adapt food sources for drought-stricken regions, reduction of chemical herbicides and pesticides, and more resilient commodity markets.

What's better for home gardeners — hybrids or heirlooms? 

Even within a long-cultivated variety, open-pollinated heirlooms have little minds of their own. The fruits in a single crop often vary in size and maturity rate, and nothing p*sses off industrial agriculture more than plants that don't march along in neat little rows, producing fruit and vegetables that all grow up at the same time and fit nicely in their pre-formed packaging. They also hold up well during the sorting and shipping process. 

Heirloom vegetables don't wear brown shirts and little red and black armbands. If they were people, they might dress like they're an eclectic female lead in Fleetwood Mac and treat maturity rates as some rock stars regard rehearsal times. You might have a favorite band, and that band might have a unique sound, but you might have entirely different experiences from one concert or album to the next.

And those long tours take their toll on musicians, just as many heirlooms aren't selected long-distance transportation. 

Hybrids also produce excellent home garden varieties

Shippability isn't the hybrid grower's only goal. Some of the most delicious and colorful home-garden favorites were painstakingly hybridized by horticulture hobbyists for the same features favored by heirloom producers: Color, flavor, and hardiness. Home canners appreciate hybrids that mature at the same rate or crosses that keep us from having to choose between growth habit and productivity. 

Here are just a few examples of popular garden vegetable hybrids: 

  • Early Girl, Better Boy, and Sweet 100 tomatoes
  • Grapefruit
  • Sweet corn
  • Seedless fruits
  • Hundreds of popular ornamental flowers, shrubs, and trees

We've been hybridizing plants ever since humans, as a whole, transitioned from hunters and gatherers to farmers and flock tenders. It's how we developed grains, turned maize into the feed and sweet corn we recognize today, and got such freaking gorgeous colors in our rose gardens and flower beds.

Take control over what you grow

Once you know the difference between hybrid plants, GMO plants, and heirloom plants, you can make educated decisions for your own health and nutrition. If you're concerned about the health of your garden and its bounty, be sure to purchase high-quality heirloom and traditionally hybridized seeds. Contact us at Seed Needs if you have any questions, or you want to share your thoughts about plant propagation techniques. We'd love to hear from you! 

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