Chlorella, a single-celled plant with a unique Chlorella Growth Factor (CGF), is a unique source of chlorophyll, nucleic acids and other phytonutrients.CGF The growth factor CGF is found in Chlorella and not in any other plant.—David C. Nelson, Ph.D.—Randall E. Merchant, Ph.D.—Michael E. Rosenbaum, MD—Shera E. Raisen, MD—Mark B. Drucker, MD—Matthias K. Maas, DC