The term 'PET THAT'S A PLANT' can be summarized by the crossword solution CHIA, which is a type of plant that is often kept as a pet. CHIA is a flowering plant in the mint family and is native to Mexico and Guatemala. It is known for its edible seeds, which are high in omega-3 fatty acids, fiber, and antioxidants. CHIA plants are easy to care for and require minimal maintenance, making them a popular choice for pet owners.