This image of the Food Variety Tree is interesting. It’s based on a study from 1983 by the Rural Advancement Foundation International, which “compared USDA listings of seed varieties sold by commercial U.S. seed houses in 1903 with those in the U.S. National Seed Storage Laboratory in 1983. The survey, which included 66 crops, found that about 93 percent of the varieties had gone extinct.”
Take tomatoes. In 1903, you had 408 varieties to choose from but by 1983, that was down to 79 varieties. Cabbage went from 544 varieties to 28 varieties. Radishes went from 463 varieties to 27 varieties. And so on.
However, 1983 was a long time ago. I would be willing bet that with all the heirlooms on the market, the number of available varieties have improved since this study came out. This is why I like to use seed catalogues that specialize in heirloom and non-GMO seeds.
Still, despite improvements, we’re not anywhere near 463 varieties of radishes on the market. Can you imagine?