The term SOUTHWESTERN PLANT can be summarized by two crossword solutions: CACTUS (6 letters) and YUCCA (5 letters). Cacti are succulent plants that are native to the Americas, and are well-adapted to arid and semi-arid climates. They are often found in the southwestern United States, Mexico, and South America. Yucca is a genus of perennial shrubs and trees that are native to the hot and dry parts of the Americas and the Caribbean. They are also commonly found in the southwestern United States.