Celery root, also known as celeriac, is a brown knobby round root topped off by skinny green stems. Its size can vary from that of a potato to that of a melon. Inside the rough brown surface is a creamy white center with a mild celery-like flavor. Unlike other root vegetables which store a lot of starch, celery root contains only about 5% starch by weight. Usually used as a flavoring in soups and stews, celery root can also be mashed in baked dishes or used raw in salads.