4.4 Resource production
Damage to flowers of S. aversiflora at different stages of floral
development did not interfere with the amount of pollen produced,
although lower values were found in damaged flowers than in intact
flowers. Florivory in the initial developmental stage of the buds could
affect anther development and pollen production, leading to the abortion
of the complete floral structure due to the lack of resource to allocate
in deformed flowers. In the intermediate or pre-anthesis stage of floral
development, florivory can affect the amount of resource through the
loss of pollen itself due to the partial or total destruction of the
anthers. According to Carper et al. (2016), florivory has the potential
to strongly affect the male function of the plant. Haas & Lortie (2020)
add that partial florivory can reduce pollen deposition because damage
to flowers reduces the frequency of pollinator visits.
Studies on the influence of florivory on pollen production are scarce inSenna species. An investigation similar to the one carried out
here with S. aversiflora on florivory at different stages of
floral development was conducted with Iris gracilipes A. Gray by
Oguro & Sakai (2009). The authors focused more on the effects of
florivory on female reproduction, which was negatively affected (Oguro
& Sakai, 2009). A study on leaf herbivory in a species of Curcubitaceae
revealed that simulated herbivory in 50% of the leaves had a strong
effect on pollen production per flower, leading to a considerable
reduction in the number of pollen grains produced by damaged plants
compared to control plants (Avila-Skar et al., 2003).
The characterization of the floral anatomy of S. aversiflora provided novel information, revealing characteristics
that are important for the taxonomic classification of the species as
well as in the understanding of its antagonistic and mutualistic
ecological relationships. The main anatomical traits that possibly
explain why S. aversiflora flowers, and especially its
petals, are highly susceptible to florivory are the thin cuticle, low
density of trichomes on the surface of the petals, absence of papillae
on the epidermis, absence of sclerenchyma and crystals in the mesophyll,
and high concentrations of nutritive chemical compounds. These
characteristics make the flowers more palatable and accessible to
florivores. Finally, we conclude that florivory has significant impacts
on the reproduction of S. aversiflora, decreasing the amount of
pollen and volume of petal tissues. These impacts underscore the
importance of the selective pressure of florivory shaping the evolution
of plants, promoting defense and regeneration strategies to ensure the
continuity of reproduction.
Author contributions
Edinalva Vital, Natan Almeida and Emília Arruda delimited the general
idea of the work. All practical steps of the work and the writing of the
original draft, including the conceptual, methodological and discursive
writing, were carried out by the first author. The co-authors Natan
Almeida, Ana Virgínia and Emília Arruda contributed to the supervision
and formal analysis of the manuscript.