you know that trees flowers and vegetables are plants. But the smallest plants are know as bacteria ( bak-TIR-ee-ya ). They are so small that you cannot see them with just your eyes. You must use a microscope to see them. The largest bacteria are only one-thousandth of an inch long, and most are much smaller than that. Bacteria are one-celled plants. While most large plants can make their own food, many bacteria cannot. Therefore, they must depend on other plants or animals for their food