Pollen morphology and reproductive biology of Calophyllum brasiliense Cambess. (Calophyllaceae)

Abstract

Pollen morphology and the reproductive biology of Calophyllum brasiliense were investigated in Parque Estadual das Fontes do Ipiranga, São Paulo, Brazil. The study encompassed pollen analyses using light, scanning, and transmission electron microscopy. Additionally, we collected data on reproductive biology, main visitors/pollinators, fruit set, and seed germination. The species exhibits individuals with perfect flowers (hermaphrodites) as well as male individuals with staminate and perfect flowers. Flowering occurs in October and November, and flowers have diurnal anthesis and pollen as a floral resource. Pollen grains are monads of medium size, isopolar, oblate-spheroidal to prolate-spheroidal, 3-(4)-zonocolporate, with exine fossulate-perforate with supratectal microechini. Hermaphrodite individuals have the highest proportion of malformed pollen due to their reduced grain size. The pollen grains from the hermaphrodite individuals displayed a low viability (0.06%), while those from male individuals had higher viability (66.38% and 55.78% for perfect and staminate flowers, respectively). The stigma was receptive throughout the anthesis period. Cross-pollination between perfect flowers of male and hermaphrodite individuals resulted in 8.80% success in fruit set, but led to the development of one abnormal seedling. Cross-pollination between staminate flowers and perfect flowers of hermaphrodite individuals showed a 7.70% success rate and the control group showed an 8.00% success rate, both groups leading to the development of normal seedlings. This tree species shows relatively low reproductive success and relies on pollinators (mainly Apis mellifera, Paratrigona subnuda, Tetragonisca angustula, and Halictidae sp. 1) for the setting of fruits and seeds.

Keywords:

• Floral visitors
• guanandi
• pollen characterization
• pollination
• reproductive system

Acknowledgements

The authors thank Prof. Dr. Elliot Watanabe Kitajima from the ‘Laboratório de Microscopia Eletrônica, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo’ for the use of the scanning electron microscope, and Prof. Dr. Pedro Duarte Novaes from the ‘Centro de Microscopia e Imagem da Faculdade de Odontologia de Piracicaba, Universidade de Campinas’ for the use of the transmission electron microscope. We thank the entire team of researchers and staff at the ‘Laboratório de Sementes, Instituto de Pesquisas Ambientais’, and Dr. Priscila Andressa Cortez from the ‘Centro de Microscopia Eletrônica, Universidade Federal de São Paulo’, for her assistance in collecting the material for microscopy. We thank the ‘Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Pesquisas Ambientais’ for technical and administrative support. Authorization was obtained for the execution of scientific activities from the Brazilian ‘Sistema de Autorização e Informação em Biodiversidade/SISBIO’ (under number 86541-1) and the PEFI managers (Cadastro e Gestão de Pesquisas/CADGP process number 000000018765/2022).

Disclosure statement

No potential conflicts of interest were reported by the author(s).

Specimens investigated

Calophyllum brasiliense Cambess. (Calophyllaceae). Brazil: São Paulo, Parque Estadual das Fontes do Ipiranga. N.S. Martarello 1, 19 November 2020 (SP526204); Brazil: São Paulo, Parque Estadual das Fontes do Ipiranga. N.S. Martarello 2, 19 November 2020 (SP526205); Brazil: São Paulo, Parque Estadual das Fontes do Ipiranga. N.S. Martarello 3, 19 November 2020 (SP526206).

Additional information

Funding

The authors are grateful for grants from: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) through the N.S. Martarello Doctoral Scholarship [process no. 141157/2019-4] and Research Productivity Scholarships granted to C. F. P. da Luz [process no. 307607/2022-4] and A. P. Martinelli [process no. 312602/2019-7].