Endosperm is the tissue produced in the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet. For example, wheat endosperm is ground into flour for bread (the rest of the grain is included as well in whole wheat flour), while barley endosperm is the main source for beer production. Other examples of endosperm that forms the bulk of the edible portion are coconut "meat" and "milk", and corn, including popcorn. Some plants like the orchids lack endosperm in their seeds.