Rhyme and Reason

Here we have the need for differentiation rearing its head again. Heirloom vegetables have been around for eons but there has been no real need to promote them until the marketplace became very crowded with competing products. I wrote about the consumer and vendor sides of this in Where's the Special and Claims and Hooks.
Last year I was introduced for the first time to heirloom tomatoes and was impressed - posting here. On a recent trip to the Union Square Greenmarket, I ran across this array of heirloom potatoes. I had never really considered a world of heirloom vegetables beyond tomatoes, but there are many: beans, corn, cucumbers, lettuce, spinach, radish, melons, potatoes, okra, peppers, peas, squash, pumpkins, squash, tomatoes, watermelons.
As with any heirloom vegetable, there are many cultivars - a number of them can be seen in the photo with names like Purple Peruvian, Russian Banana, Rose Finn, LaRatte, etc.
I have not tried any of these, but I plan to - with the plethora of food and product options out there, I think it only makes sense to judge on merit and on a case by case basis - some trends are great, some just marketing spin.
Regarding the title of this posting. It once occurred to me that there was something quite curious about potatoes and tomatoes - they only had each other as good word rhymes and they were also both members of the nightshade family (plant family Solanaceae which includes potato, tomato, peppers, eggplant, tobacco. It also includes some poisonous plants). At one time many years ago a friend into Macrobiotics told me that the reason they avoid nightshades is because they are extremely yin. Many years later, a friend told me that the reason her mother, who had arthritis, avoided nightshades was because the alkaloids (primarily solanine) aggravate the condition. However, I'm still intrigued about the connections via rhyme and reason ...