Florivory in twoChamaecristaspecies: Are secretory trichomes effective against florivores?

Abstract

AbstractFlorivory inChamaecristavaries in occurrence, intensity, and the floral structures affected. As flowers are multifunctional units, the type of damage can impact reproductive success in different ways. Oil‐resin‐secreting trichomes, present in the sepals ofChamaecristaspecies, section Absus, are suggested to inhibit florivory. We recorded florivory inChamaecrista catharticaandChamaecrista catharticoidesin order to determine the frequency of damage, floral whorls most damaged, impact on reproduction, and effectiveness of secretory trichomes in inhibiting florivory. The study was conducted in the Parque Estadual do Ibitipoca, Brazil. Twenty individuals of each species were monitored monthly over two bloom periods to record the flowering intensity, rates of florivory, and fruit set and to determine the effectiveness of trichomes in inhibiting florivory. The two species had different flowering patterns, annual forC. catharticaand continuous forC. catharticoides, both more intense during summer. Florivory occurred mainly in the winter and affected floral structures unevenly, resulting in loss of different floral functions. Florivory reduced the fruit set of both species, butC. catharticoideswas considerably more impacted. The diversity of damaged structures inC. catharticoidesresulted in direct (reduced female and male fitness due to loss of ovules and pollen grains) and indirect (loss of floral resources and reduced floral attractiveness) impacts. Damage to the tubular petal could further result in loss of specialized pollination mechanisms mediated by this structure. Secretory trichomes on the abaxial surface of sepals inhibited florivory of buds and herbivory of early‐developing fruits.