PROGAMIC PHASE AND FERTILIZATION IN GASTERIA-VERRUCOSA (MILL) DUVAL,H- POLLINATION SIGNALS

A summary is given of the pollen tube pathway, the interactions during the progamic phase and the incompatibility system of Gasteria. Pollen coating substances stimulate pollen tube ovular penetration and fruit set in cases of cross-pollination. Pollen coating substances also sti mulate the water supply of the pistil which completes the pollen tube pathway. These two types of signals are related to recognition reactio ns, as well as to the activation of the pistil. Because the pollen coa ting substance is of sporophytic origin, the incompatibility system ty pe is discussed.