Heirloom, hybrid, open pollinated… Seed catalogs are full of items that use these descriptions and they are, by and large, used so inconsistently that they have become almost meaningless. A lot of the fault for this lies with the seed industry, as companies have sought to distinguish themselves by providing the “purest” seed possible. This page contains definitions for the terminology as we use it in the catalog.
There is no clear definition for heirloom. The common criteria include that the variety is true breeding in some form, that it was bred conventionally, and that it has existed for some arbitrary period of time – some say 50 years, while others say 100 or more.
Our definition is simple: An heirloom is a variety that is either true breeding from seed or when propagated clonally and was bred at least 50 years ago or long enough that nobody remembers who bred it or when.
We consider a variety of modern origin if it was bred in the past 50 years. It can be true breeding, a hybrid, a grex, a mix, or anything else. The only distinguishing factor is that we know that it was bred in the past 50 years.
True breeding varieties can be grown from seed to produce progeny that are all the same phenotype as the parent. When a variety grows true from seed, that means that it is substantially homozygous. All copies of each gene that are important to the plant’s phenotype are the same. Varieties that are substantially homozygous evolve slowly because we have eliminated most of the variability in the genome. They are inbred.
A hybrid is the result of crossing between two different varieties or species. The cross can be made by any number of means. Most commonly, hybrids are made between two varieties of the same species, but it is also possible to create crosses between different species in the same genus (interspecific hybrids) and between members of different genera (intergeneric hybrids). We note interspecific and intergeneric hybrids in the catalog.
Hybrid is not synonymous with GMO. GMOs are usually hybrids, but most hybrids are not GMO. Hybridization is the natural mode of reproduction for most plants. True breeding varieties are most commonly created by man. There has been a lot of misinformation put forth on this subject. A hybrid is substantially heterozygous. Some, perhaps even most, of the genes that are important to the plant’s phenotype have different values. When recombined, they produce new phenotypes. Varieties that are substantially heterozygous evolve quickly because many different phenotypes will be expressed in the first few generations of offspring.
Many plants are propagated as clones. Any time that you start a plant from a part other than seed, you are cloning it. For example, tubers are clones of the parent plant. Cuttings of any sort are also clones. Plants that are reproduced clonally are almost always hybrids; if you grow seed from them, you don’t get the same phenotype as the parent.
This is perhaps the most abused term of all. In most seed catalogs it has come to be synonymous with “true breeding,” but that really isn’t what it means. Open pollination is allowing nature to take care of the pollination: it could be done by insects, birds, wind, or even by man as long as the pollination is done indiscriminately. I think “open pollinated” became a synonym of “true breeding” because you can produce seeds that will grow true if you have an isolated population of a single true breeding variety that you allow to be open pollinated. Still, it is equally open pollination to grow different varieties together and allow them to intermix, which produces hybrids.
When we use the term “open pollinated” in our descriptions, we mean it literally. Seeds that we describe as open pollinated are generally genetically diverse, with multiple pollinators. We may offer open pollinated seed of an individual variety or a mix of different varieties. In the first case, there is only one female parent, but potentially many male parents. In the second case, there are multiple male and female parents.