1. In this investigation a comparison was made of the morphological development of buds on olive trees held under either greenhouse temperature conditions or natural winter temperature conditions at Davis, California. 2. The flowering ability of olive trees exposed only to a portion of the natural winter chilling period was compared with that of trees exposed to the entire natural chilling period. 3. Buds from chilled trees started increasing in fresh weight about the first of February, while buds from non-chilled trees showed no increase in weight. 4. A comparison of longisections of buds from chilled and non-chilled trees sampled February 19 shows that, by this date, there was an elongation of the axis and broadening of the apical meristem with incipient initiation of lateral organs in buds of only the chilled trees. There was no evidence of initiation of flower primordia in buds from chilled trees until March 18. 5. During the period November 6, 1961, to April 2, 1962, there was little or no evidence of morphological change in buds from non-chilled trees. 6. These morphological studies show that the initiation of flower primordia in the olive is completely inhibited by high-temperature treatment during the fall and winter months. 7. Trees exposed to 1240 hours of temperatures below 45⚬ F. formed very few inflorescences as compared to those exposed to the entire natural chilling period (1852 hours below 45⚬ F.). 8. It appears that the striking increase in ability of buds to form inflorescences after an increase in low-temperature exposure from 1240 to 1850 hours below 45⚬ F. was associated with the initial morphological changes in the buds in response to low-temperature treatment.