The Rangpur is a small, intensely acidic citrus with the loose, easy-peeling orange skin of a mandarin and the fierce sourness of a lime — despite the name it is neither a true lime nor an orange, but a mandarin-and-lemon (or citron) hybrid. Orange-fleshed and aromatic, it is prized as a hardy, juicy souring fruit and as a vigorous rootstock for other citrus.