Varying in color from deep blue to purple or almost black, the large, round Concord grape grows in loose clusters on sturdy vines. A powdery film, or bloom, develops on the skin’s surface. They have thick, tannin-rich skins that are slightly chewy, and juicy, jelly-like pulp. Their flesh can be seedy and almost translucent, with a slight green tinge, and is tangy and flavorful.