ALL0-9ABCDEFGHIJKLMNOPQRSTUVWXYZ Share This Tweet Share A structural, functional unit of a plant. Related Images:Related Articles: Gibberellic acid in plantsGibberellic acid (GA), a plumeria hormone stimulating plant growth and development, is a tetracyclic di-terpenoid compound...Learn More Glossary: AuxinFertilizer BasicsGlossary: CytokininWater Uptake and Transport in Vascular Plants