My inquiry into genetic diversity has grown during the last three years of incorporating native food plants into my kitchen garden. I noticed right off that unlike traditional garden varieties, native food plants tend to produce edibles parts that do not all look alike. The first year my Hopi Pumpkin, (Cucurbita pepo - a summer squash) produced fruits that were either roundish and stripped, or longish and stripped. On closer examination, you could see that no two fruits were “look-a-likes”, as you would expect to see in the zucchini squash, (C. pepo) bin at the local supermarket.

That year I saved seed from the roundish form and planted them the next year. The second year I saw no longish fruit, nor has my seed line produced any longish fruit since. This year was the first year that I have seen fruit that is plain pale green without a single dark stripe. This year I saved seed from the plain green fruits and will plant them next year. Is this a case of my selectivity causing a loss of genetic diversity in my own garden? Obviously, the full range of genetic diversity would benefit by saving seeds from as wide a variety of plant characteristics as possible.

It is not just Pinto Beans where you can see these differences in diversity between modern varieties and native varieties. It shows up in Hopi Yellow Limas (P. lunatis) as well – in a very distinct dark maroon variant as well as an unmarked yellow variant, with the bulk of seeds falling somewhere in between those two extremes.

Variation in genetic characteristics is not limited to color and size in seeds, but shows up as well in yield characteristics, plant growth and environmental tolerance. Not surprisingly, these genetic variations are even greater in Tepary Beans (P. acutifolius). Diversity research with many genotypes of Teparies has shown wide variations for plant growth, number of pods per plant and number of seeds per pod. The published research studies show only moderate variation in seed weight per 100 seeds, but the varieties selected did not include the San Felipe Pueblo White Tepary, which has a huge seed (for Teparies) and produced as prolifically (in my garden) as other varieties.

At the highest level, that is what keeps us safely fed. Consider the Irish Potato Famine, caused by an airborne fungus (phytophthora infestans) and a monoculture of the Irish Cobbler potato. Consider the Southern corn leaf blight that severely reduced corn production in the United States in 1970, caused by the lack of genetic diversity in corn. Consider the current threat to vast monocultures of Cavendish cultivar bananas caused by Black Sigatoka, also known as black leaf streak. At the same time, we have lost many of the native varieties of bananas that contain genetic resistance to diseases. (1)

It has been demonstrated many times that the loss of genetic diversity through monoculture leads to problems with food crops. So why do we keep valuing, selecting for and producing uniformity? Fortunately, there are still local and native growers who value and select for diversity, as well as several organizations working to preserve localized landraces of food plants.