Stylar develompent in the open flower of Gasteria verrucosa (Mill.) H. Duval

In the style of Gasteria changes occur during the five days after anthesis. The stigma becomes receptive for pollen at the time that the perianth starts wilting. The top of the style has a very narrow canal, surrounded by the thick walled papillar and inner epidermal cells. This canal enlarges basipetally and contains a viscous exudate. During the development, the exudate gets osmiophilic granules which disappear when the pollen tube passes. The cells at the top of the style show some structural differences compared with the other stylar cells, especially in their vacuolation, secretion and number of mitochondrial cristae. Slight cellular changes occur during the passing of the pollen tubes. The other stylar cells seem to have mainly a secretory activity. The papillar cells along the ovules have a transfer cell character. The hollow style of the succulent Gasteria may be considered to be a functional solid style with a gradient in the cell wall of the transmitting tissue from solid at the top to fluid at the base.