Changes in fresh and dry weight, content of sugars and starch and activities of α-amylase and acid invertase were determined during various stages of ray floret development and senescence inChrysanthemum. Total and reducing sugars increased until the ray florets attained their maximal expansion, peak fresh and dry weights. This coincided with the highest activity of invertase. Starch content and maximal activity of α-amylase declined much earlier. It is presumed that invertase rather than α-amylase plays a major role in the expansion of ray florets inChrysanthemum. Senescing stages of ray floret are characterized by decrease in fresh and dry weights and loss of metabolites and a marked decline in the activities of both invertase and α-amylase.