Hare. J. Daniel. 2002. Seasonal variation in the leaf resin components of Mimulus aurantiacus. Biochemical Systematics and Ecology 30: 709-720.

Abstract: The chaparral subshrub, Mimulus aurantiacus, produces leaf surface resins in excess of 30% of leaf dry weight. The resin provides some defense against the insect herbivore, Euphydryas chalcedona, and perhaps from desiccation and injury from UV light. The resin is comprised of six flavanones and an a -pyrone. The different components may differ in their ecological roles. Methoxylated components may be most effective as antidesiccants. Because plants face different risks at different times of the year, they may vary seasonally in resin composition. The quantities of each component from plants from five different populations but reared in a common garden were determined at 12 monthly intervals. Three hypotheses were tested: 1) plants would produce greater proportions of methoxylated components as drought stress increased during the season, 2) such increases would be greater for plants from the more xeric sites, and 3) the production of methoxylated components would occur at the expense of analogous unmethoxylated components. Resin quantity and composition differed significantly and consistently among populations, however, the seasonal increase in the proportional production of methoxylated components was slight relative to the consistent differences among populations. The production of all but one component were highly, positively correlated. The strong positive correlations among the concentrations of the five geranylflavanones suggests that their synthesis is limited by the synthesis of the geranylflavanone nucleus, and not by the attachment of different functional groups with presumably differing ecological roles.