The American tropical plant crossword solutions are guava (5 letters) and cassava (6 letters). Guava is a small, round fruit with a yellow or green skin and a sweet, white flesh. It is native to tropical America and is widely cultivated in the tropics. Cassava is a woody shrub native to South America and the Caribbean. It is a major source of carbohydrates for many tropical countries and is used to make flour, tapioca, and other products.