The oldest type of seeds available on the commercial market are heirlooms and open-pollinated seeds. An heirloom is an older, open-pollinated seed variety that has been out of general commercial production. These unusual cultivars have been raised in rural or isolated communities by gardeners and farmers who grow the plants both for their food and for their seeds, which are replanted the next season. Heirlooms are usually over a hundred years old; no seed is considered an heirloom if the variety was developed after World War II.
Heirloom seeds have great histories and their stories are part of the history of the farming generations that raised them. Some naturally green and brown cotton seeds, such as Natchez Brown, were open pollinated brown cotton seeds that were saved through natural selection generation after generation, starting with the slaves on southern plantations who were allowed to grow a few small crops of their own--but not white cotton. The brown cotton allowed them to spin and weave cloth with a lovely warm color intrinsic to the fiber.
Besides their stories, heirlooms are known for their biodiversity and the way they have evolved over the years to grow well in one ecosystem. When farmers select the best plants to use as seeds for the next year, they were naturally selecting for disease resistance and good growth. These characteristics continue to be valued by farmers who use heirloom seeds. They are also fun plants to grow, as they come in colors, sizes, and shapes that are not regularly seen.
Open Pollinated Seeds
Open pollinated means the new generation of seeds will grow into the same plant as the parents. All heirlooms are open pollinated, but at its most specific, it just means the plants are either self-pollinated or pollinated by another plant of the same variety. In a garden with multiple types of pepper plants, for instance, a gardener cannot really get open pollinated peppers, but instead will have seeds at the end of the year that are cross-pollinated--the peppers all pollinated each other, and the new plants might have some characteristics of either of the parent pepper plants. On a commercial scale, open pollinated seeds are carefully segregated so this type of natural cross-pollination doesn't happen.
The cross-pollination described above is how hybrid plants are developed. Rather than each parent plant being the same variety, hybrids might have one parent plant selected for taste and one selected for disease resistance. Specific qualities for different growing regions, such as shorter growing seasons or selective resistance to local pests, can be developed into a new plant by cross-pollinating.
For commercial seed production after 1945, one group of seed developers worked on cross-pollinating seeds that would work well for farmers--specifically, they would all get ripe at the same time, so they could be picked all at the same time. Other seed companies developed hybrid seeds for the home gardener, and this is where some of our most prolific and best tasting foods have come from. We have pumpkins that are beautiful, with sweet, non-stringy flesh, and sized for a single pie. We have cukes that are the size & color of lemons, while some that are perfect for pickles. The great variety of produce a home gardener can grow is the result of cross-pollinating to make hybrids.
Concern about chemicals and pesticides on food has led to significant selection of varieties that are resistant to specific regional pests and diseases. Varieties that are naturally highly resistant to fungal disease are going to be popular in the humid south, for instance.
This type of cross-pollination for specific characteristics used to be done at home, on smallholdings and farms. Since 1945, most of the cross-pollination for specific plant characteristics has been done by plant developers in university agriculture departments. These seeds are called hybrids because they are developed from cross-pollinating two varieties- their parent seeds are two varieties of the same plant. So the seeds they produce will not be true to themselves. To grow a hybrid plant, the seeds need to have been cross-pollinated.
GMO seeds are something else entirely. While hybrids can be thought of as "sweet tomato plus big tomato equals big sweet tomato," genetically modified seeds have had the DNA of a different species spliced into their DNA. GMO seeds can have DNA from viruses, bacteria, other plants, or animals added to the seeds--rather than cross-pollination, this technology is mixing two species.
Rice had been modified to contain more protein, with the idea that a world population needs more protein from their rice. Vegetables have been modified so they contain more vitamins and minerals that their usual species. Some varieties have been modified so they resist natural pests, and thus the need for pesticides is reduced, which can be very dangerous.
Several concerns about GMO seeds continues to shadow their acceptance by people across the world. Since the GMO seeds are a new species, they can be patented and owned by the developer. We also do not know what the consequences are when these seeds get out into the world and start cross pollinating with other plants.