there are over 100 chia varieties
there are variants of the most potent strains of chia
They are: Solid black, mottled grey black, and white or cream.
Note that the last two comprise what is generally being grown and sold today as black chia, and are the source from which essentially all chia originated.
These 3 "types" have been referred to as: varieties, selections, strains, to name a few terms used.
Truly the best description as to what these should be called are germplasm lines.
In no way are they varieties nor strains. People have been simply using these “buzz” words as marketing tools.
The following technical definitions are provided by a very well qualified plant scientist. Use them to help you decide.
Cultivar: A cultivar is a cultivated variety. This is a bred and released line which has something different from others which will give growers certain characteristics repeatedly. In other words, a cultivar is a group of plants selected for desirable characteristics that can be maintained by different propagation techniques. This, although not very recent, is a newer term for what we used to call varieties. To the point, cultivars have characteristics that are easily distinguishable from other cultivars, and the characteristic is uniform/stable under repeated propagation. The plants in a cultivar may not all be genetically identical, but they breed true for the desired characteristics. Even though we all use these terms, Variety, Selection and Strain can be confusing, ambiguous and often interchanged, which just adds to confusion among non-plant breeders. We all talk about “improving strains,” for instance, but strain can mean different things to different people, so perhaps best to avoid these terms.
Variety: This is a released line that is genetically different and should breed true for whatever traits it has been bred for. The term variety is also confused because in botanical hierarchies, there can be varieties found under species that have nothing to do with plant breeding. Selection: Selection is really a technique where a new or desired trait is chosen by a plant breeder, and really depends upon the mode of reproduction for the plant. These techniques can range from single-plant selection, to half-sib selection, to full-sib selection, to mass selection, among others, all depending upon the plants reproductive biology. In many new/alternative crops, much improvement has been done by either mass selection, where the best plants are selected for a trait, and their seed bulked and then planted the next generation; or single-plant selection, where individuals with desired traits are selected and their progeny tested for the trait. Unfortunately, the progeny of these techniques are often just called selections, and that name can stick for quite some time.
Strain: Here is an example of how terms get confused from the Vegetable Seed Saving Handbook, under the section title of How to Select a New Strain from an Existing Variety: “The easiest way to create new plant varieties is by simple 'selection.' Selection means allowing only plants that show desirable traits to produce seeds. If any plants don't show the traits you are looking for, you prevent them from pollinating the plants you have selected.” Strain is a word we all use, but its exact meaning is often dependent upon context.
Germplasm: Is all of the genetic resources for a species (plant or animal).
Germplasm line: Is a breeding stock that is maintained to preserve genetic diversity from which selections can be made (a valuable resource for breeders). Germplasm lines can be land races, open pollinated varieties, exotic accessions, wild species, etc., and are usually in a germplasm collection (e.g., USDA or a seed company). Whether from an individual or a group of plants, a germplasm line contains enough genetic diversity from which selections can be made, and often have a specific marker genotype (e.g., black seed or white seed). A plant breeder would take a germplasm line, make selections and make it uniform for the desired traits.