The pattern of distribution of ¹⁴C-labelled assimilates translocated from a leaf on the flower stem of carnation was found to vary with both the ambient air temperature and the localized temperature of the flower bud. A high bud temperature increased the proportion ofassimilates moving into the floral tissues while a low bud temperature increased the proportion accumulating in the stem above the source leaf. When the air temperature was raised independently of the bud temperature, the stem gained assimilates at the expense of the flower, but if both air temperature and bud temperature were raised together, effects of bud temperature predominated and movement of assimilates into the flower was promoted. The role of the flower in mediating effects of temperature is discussed with reference to the distribution of invertase activity in the shoot.