Florivory defence: are phenolic compounds distributed differently within perianths?

Plants might allocate chemical defenses unequally within attractive units of flowers including petals, sepals, and bracts because of variations in the probability of florivory. Based on the optimal defense theory, which predicts that plants allocate higher chemical defenses to tissues with higher probabilities of herbivore attack, we predicted that distal parts and sepals would have higher chemical defense allocations than proximal parts and petals. To test this prediction, we compared total phenolics and condensed tannins concentrations as well as presence of florivory within attractive units of ten angiosperm species. In agreement with the prediction, the overall results showed that the distal parts had higher total phenolics and condensed tannins than the proximal parts. On the other hand, contrary to the prediction, petals and sepals showed no tissue-specific variations. Florivory was more severe on the distal parts than the proximal parts, although statistical support for the varia...