https://www.abc.botanic.hr/index.php/abc/article/view/1065?articlesBySimilarityPage=10
Variability of pollen aperture heteromorphism in annual pansies (Viola Section Melanium) | Acta...
Pollen heteromorphism is frequent in the section Melanium of the genus Viola, in which over 80% of the species produces pollen morphs with 3 to 6 apertures....
variabilitypollenapertureheteromorphismannual