SummaryHistological examination of the ovary walls from ethylene-treated cut flowering stems of the carnation showed that the cells had enlarged and this appeared to account for the increased growth of the ovary which follows ethylene treatment of this flower. Sugar analyses of the flower parts indicated that growth of the ovary was accompanied by an increase in the ratio of sucrose to reducing sugars in the petals and ovary, and a net increase in sugars in the ovary. A sugar, tentatively identified as xylose, increased in the petals after ethylene treatment. Nitrogen, phosphorus and potassium contents of the ovary also increased after the ethylene treatment. The results, consistent with the hypothesis that sucrose is translocated in response to ethylene, are discussed in relation to previous work relating to the involvement of ethylene in flower senescence.