PSCIdb [Plant Stem Cell Informatics Database] is a comprehensive collection of genes related to plant stem cell. Plant stem cells are innately undifferentiated cells located in the meristems of plant. They serve as the origin of plant vitality, as they maintain themselves while providing a steady supply of precursor cells to form differentiated tissues and organs in the plant. The specification of stem cells and establishment of stem-cell harboring structures mediated the explosive radiation of land plants, which shaped the biosphere and eventually resulting in the abundant and diverse terrestrial plant communities.