Celery actually comes in a variety of colors from sheer white to vibrant gold to rich red and deep green. In this genus/species of plant (Apium graveolens) are also found two other important types of celery. The first is celeriac (also called root celery, turnip-root celery, or knob celery). Just like the name suggests, root celery is characterized by a large root ball, which is especially prized for its unique somewhat nut-like taste. (The scientific name for celeriac is Apium graveolens var.