Experimental design and plant material. (A) Experimental design: fluorescent Ca2+ indicator was injected directly into the inflorescence peduncle just after it was harvested from the tree. (B) Morphology of the olive pistil harvested from an opening flower (stage 2). (C) Longitudinal section of a mature pistil of an open flower after fixation and methylene blue staining. (D) Transverse section of an ovary from a mature pistil of a flower with dehiscent anthers after fixation and methylene blue staining. (E-I) Olive flower developmental stages viewed using a stereomicroscope. (E) stage 1, green flower bud; (F) stage 2, opening flower; (G) stage 3, open flower with turgid yellow anthers; (H) stage 4, open flower with dehiscent anthers; (I) stage 5, flower without anthers and petals, brown stigma, and thick ovary. EN - endocarp, EP - epidermis, ME - mesocarp, O - ovary, OV - ovule, LO - loculus, P - placenta, S - stigma, ST - style, VB - vascular bundles. Bars = 0.5 mm.