1. Observations on the male gametophyte of Enkianthus cernuus, E. perulatus, and E. campanulatus are reported. 2. The anthers are characterized by a glandular tapetum and a prominent, fibrous endothecium. 3. The single pollen grains exhibit a dimorphism in size and an unstable number of germ pores: E. cernuus and E. campanulatus have three or four, while E. perulatus has four or five. 4. Development of the microgametophytes is synchronous. It is similar in the three species resulting in mature pollen grains which are three-celled. The male gametes are distinct cells throughout. The vegetative nucleus shows no signs of degeneration in the pollen grains. 5. Pollen-tube growth within the anther, a rare phenomenon in angiosperms, is reported in E. perulatus. Some instances of abnormal development of pollen grains in E. campanulatus are described. 6. The peculiarities of the stamen and male gametophyte in Enkianthus, added to its other unusual features for a member of the Andromedeae of the Ericaceae, suggest ...