Cytogenetics of Hypericum caprifoliatum Cham. & Schltdl. (Clusiaceae) populations and other species of the genus
Ana Paula Guisso Navarini, Maria Teresa Schifino-Wittmann, Ingrid Bergman Inchausti de Barros, and Danielle Almeida
Chromosome numbers and meiotic behavior are presented for the first time for Hypericum caprifoliatum (2n=48), H. cf carinatum (2n=48) and H. polyanthemum (2n= 32) and confirmed the H. perforatum (2n=32) number. Chromosomes are very small (ca. 1 to 2 mm). Meiotic irregularities, such as uni and multivalents, un-oriented chromosomes, bridges and laggards were very frequent in H. caprifoliatum and H. cf carinatum. Meiotic indexes ranged from 44.0 to 73.0% in H. caprifoliatum, 66.0 to 77.0% in H. cf carinatum and was 80.0% for the H. polyanthemum population. Pollen fertility ranged from 42.0 to 88.0% in H. caprifoliatum, 65.0 to 88.0% in H. cf carinatum and was 89.0% for H. polyanthemum. Together with literature and meiotic behavior data, the great variability in pollen size and fertility within and among populations of H. caprifoliatum and H. cf carinatum could suggest that, as many other Hypericum species, these taxa are apomictic.