Gibberellin-like substances and an auxin similar to IAA were detected by bioassays in extracts of flowers of Chrysanthemum morifolium. The activity of these substances was shown to reach a maximum early in the development of the flower when its relative growth-rate was at a maximum, and then to decline with the relative growth-rate. The leaves of lateral flowering shoots were found to contain gibberellins similar to those detected in the flowers while a different gibberellin, which appeared to decrease in activity with the age of the shoot, was detected in the stem. An auxin similar to indol-3yl-acetic acid (IAA) was also detected in these stems. Growth-promoting substances were not detected in the old stems and leaves from the main shoot. Gas-liquid chromatography revealed the presence of a number of additional gibberellins in the flowers. The chemical nature of the growth substances is discussed in relation to their biological and chromatographic behaviour.
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Jeffcoat et al. (1972) studied this question.