Palynological study of the genus Gypsophila in Iran

Gypsophila with approximately 150 speciesrepresents the fourth largest genus of Caryophyllaceae and the second genus of tribe Caryophylleae. Iran is the second main center of Gypsophila diversity with 38 species in the world. Considering Gypsophila as one of the most polymorphic genus of the family andalmost half of its taxa distributed in Iran as endemic, thus makes it as a significant genus from taxonomic and nomenclatural points of view. Moreover, following the IUCN Red List criteria, about half of these endemic taxa are categorized as Critically Endangered (CR D.); hence, the protection of these taxa and their limited habitats is necessary. Pollen grains of 40 taxa (Table 1) were studied by electron microscopy for the first time in Iran (Figs 2–5). However, these attributions do not support sections which are made based on morphological characters and rather can be used to separate some close taxa. The pollen grains of Gypsophila are monade, apolar, pantoporate with 12 pores, rounded polyhedral, tectate with granulate microechinate-microperforate ornamentation. Pores are annulate, operculate. Pollen grains size (20.7–32 µm), operculum diameter (1.6–6 µm), distance between pores (2.3–7 µm) and operculum thickness are variable among taxa (Table 2). Gypsophila pilosa var. pilosa, and G. platyphylla have the largest while G. antoninae has the smallest pollen grains. The smallest pores and, therefore, the minimum diameter of the operculums can be seen in G. acantholimoides. The largest and thickest operculum is owned by G. virgata. A phenogram of Iranian Gypsophila taxa derived from palynological analysis using UPGMA method is also given herewith (Fig. 1).