Botany of Thanksgiving Everyone has their own list of things to be grateful for at Thanksgiving. Along with your thoughts of turkey and football, take a minute to appreciate the plants, yes, the plants, that originated in the Americas, that add flavor, color and nutrition to your Thanksgiving table. T
hese plants include corn, beans, squashes, potatoes, sweet potatoes, and cranberries. You might not realize that these plants are all New World species, that is, they originated in the Western Hemisphere. Many of our foodstuffs, such as wheat, barley and chick peas were domesticated from plants found growing in the Fertile Crescent, an area touching the modern countries of Israel, Jordan, Syria, Lebanon, eastern Turkey, western Iran, and northern Iraq. But most of our traditional Thanksgiving side dishes were domesticated here in the Western Hemisphere, mostly in Central or South America.
So, these dishes are uniquely American, and I mean American in the broadest sense, from North, Central and South America. Except for potatoes and sweet potatoes, these wonderful foods are all fruits; and as with all fruits, the part you eat is the swollen ovary that developed after the flower was fertilized. Yes! That’s right- plant sex right on your Thanksgiving table!
Here is a little history celebrating the plants that originated nearby and are worthy of special note on Thanksgiving. Many of you are likely familiar with the Three Sisters companion planting system, where corn, squash and beans are grown together. Early Central American farmers would plant several corn kernels together in a single hill. Once the corn got to be about 6 inches tall, the farmer planted the beans. These were all vining beans, and the bean vines climbed the cornstalk, which provided a scaffold for the growing beans. Finally, squash was also planted at the base of the cornstalks. Their large leaves provided shade to help keep the soil moist and cool, and helped keep down the weeds. Not only did these plants help each other grow, but together their fruits provided a meal with a healthy balance of proteins, carbohydrates, fats and vitamins.
Corn, also known as maize, and by its scientific name Zea mays, is a member of the grass family. Corn was domesticated about 9000 years ago in southern Mexico. The earliest maize plants grew only small, 1-inch long corn cobs and only one per plant. Likely, several centuries of artificial selection by the native people resulted in the development of corn plants with larger, and multiple cobs. Native farmers bred corn to adapt to northern climates, and corn became a staple crop throughout the Americas. Beans in the genus Phaseolus are native to the New World and have been cultivated since pre-Columbian times. These include the common bean, lima beans and scarlet running beans. These were the original pole beans that climbed the cornstalk. Beans have an extra trick to offer the Three Sisters planting scheme; bean roots have special nodules that take nitrogen out of the air and turn it into fertilizer for the growing plants. Some kinds of beans can be dried and stored for winter, providing a year-round source of food.
Squash is the third part of the Three Sisters trio. Pumpkins and squashes are all in the cucurbit family, which also includes plants not indigenous to the Americas, including gourds, cucumbers, cantaloupe and watermelon. But squash and pumpkins are native to the Andes up to southern North America and have been cultivated for at least 7000 years.
Like super-heroes in the movies, corn, beans and squash all bring amazing powers to the trio. Potatoes are in the Solanaceae plant family, another plant family where we find several edible crops including peppers and tomatoes. Potatoes were domesticated in the mountains of Peru between 5000 and 8000BC. Sweet potatoes are in the morning glory family, and not related to potatoes at all. Both potatoes and sweet potatoes are not fruits like our other Thanksgiving plants but are tubers, or the underground swollen stems where the plant stores carbohydrates and nutrients for the next year’s growth.
Perhaps the most iconic Thanksgiving fruit is the cranberry. This tart berry grows in our own Northwoods bogs. I’ll bet you could find a naturally growing cranberry within a few miles of wherever you are, presuming you are listening in the Northwoods. Cranberries have beautiful little flowers that bloom in July. Someone thought the white petals looked like wings of a crane thrown back in flight and the yellow stamens like the bird’s beak. The original name of this plant was the craneberry but is now, of course, known as cranberry.
So please give thanks to these tasty, nutritious and native New World species this Thanksgiving!
For Field Notes, this is Susan Knight of UW-Madison’s Trout Lake Station.
