In vitro pollen germination of pollen is simple and fully quantitative test for assaying pollen viability and also can be exploited for study of pollen physiology. A nutrient medium (in vitro) is supplemented with some essential compounds necessary for pollen germination and tube growth. During in vitro pollen germination and tube growth not only enzyme activity but also the effect of carbohydrates, boron, calcium, hormones, light and other factors have been studied for different plants. Here Datura metel L. was selected. In order to get maximum germination and tube growth in this taxon, modification of the basal medium of Brewbaker and Kwack was used. This book is helpful to understand the pollen physiology.