SUMMARYPoly‐ethylene glycol (PEG)‐400 was found to be superior to sucrose as the major component in media for the germination ofPetunia hybridapollen. PEG promotes pollen tube growth considerably more than sucrose. Pollen tubes grown on PEG resemble thein vivotubes much more than those grown on sucrose. The respiration rate of pollen germinating on sucrose is 33% higher than on PEG; the extra energy produced is clearly not related to tube gro