The Role of Plants in the Colombian Exchange timeline

(New World → Old World) Cause: Corn was the principal crop of the Americas. Corn gained popularity in colonies and Old World due to its production. Effect: Corn allowed population to grow. The biggest effect corn had was how it allowed a larger population, how far it spread (Africa, China, etc), and how it still is a large part of our diets.

(Old World → New World) Cause:
Europeans needed wheat to mill into flour, which was used for many purposes, but mostly bread. Effect:
Wheat thrived in South America and was therefore able to supply Spanish colonies. The biggest impact of wheat in the New World is how worldwide wheat has become. Today, wheat is eaten around the world.

(Old World → New World) Cause:
The use of cotton in textiles is an ancient practice, so it would make sense for colonists to grow their own cotton plants. In the 16th century, the Spanish cultivated a cotton crop in what is modern-day Florida. Effect:
Cotton became a stream of income because the fibers of American cotton were longer. Cotton is a labor-intensive crop and one of the reasons African slaves were used in the Americas, which is one of the biggest impacts.

(New World → Old World) Cause: Potatoes are endemic to Peru. They were a good food source and spread to North America and Northen Europe. Effect: Potatoes became a staple in Germany, Russia, and especially Ireland. It is estimated the poorer classes of Ireland ate 19 potatoes a day per person. The biggest effect of the introduction of the potato was the population boom it caused because it allowed more food to be grown in less land. Another effect would be the Irish potato famine.

(New World → Old World) Cause: Spanish conquistadors were the first to consume chocolate when they encountered the Aztecs. The Aztecs mixed corn, cocoa, vanilla, chilies, and achiote seeds to make a drink. Cocoa beans were sent to Spain, where sugar was added to the drink. Effect: Cocoa quickly became popular in Europe and European colonies. Cocoa spread to Africa, where it still grows today, and is a major export, which is a major effect.

(New World → Old World) Cause: Originally, only natives of San Salvador smoked tobacco but it quickly spread throughout South America while the Spanish cultivated it in America. Europeans quickly became addicted. Effect: Tobacco immediately became very popular in Europe. Tobacco was taxed, generating income. Tobacco is a labor-intensive crop and became a driving force of importation of African slaves.

(Old World → New World) Cause: Drinking tea is an ancient practice and was embedded in European culture. Tea was able to be grown in the New World and be traded. Effect: Tea was taxed so it became a source of income for European countries. The biggest effect tea had was its ability to produce money for European countries.

(Old World → New World) Cause:
Coffee plants were introduced to Europe in the 17th century and it quickly became very popular. A French officer brought a coffee plant to the Caribbean, where it thrived and then spread throughout the island and South America. Effect:
Coffee became a source of income for many European countries, especially Portugal. The biggest impact of coffee was the South American coffee empires that still exist today.