The plant growth hormone (phytohormone) gibberellic acid is the best known member of the group of gibberellins. Diterpenoid carboxylic acid promotes germination and its rapid growth, stimulates elongation growth and fertilization of vascular plants and reverses hibernation. Higher concentrations of gibberellic acids, which are found in moss protonema, affect gravitropism and elongation growth. Gibberellic acid is produced in the plastids of young leaves, and in immature seeds and fruits in order to promote maturation.