Enhancement of Gibberellin Growth-Promoting Activity by Hydrangenol Isolated from Leaves of Hydrangea Macrophylla

Abstract
The aglycone and glucoside of hydrangenol (4''8-dihydroxy 3,4-dihydro isocoumarin) were isolated from leaves of Engel''s White hydrangeas. The aglycone of hydrangenol by itself possessed little or no biological activity but when applied to several test species it enhanced the activity of low concentrations of applied gibberellin.