Geographic variation in the pollen of Silene latifolia (S. alba, S. pratensis): a quantitative morphological analysis of population data

Publisher Website
Google Scholar
Abstract
There is a geographic separation of the two pollen morphs in European Silene latifolia, with the changeover zone running northwest – southeast from the Netherlands to Greece. Reticulate grains are characteristic of western populations and microechinate grains are characteristic of eastern populations. The present study is based on a sample of one pollen grain from each of the male individuals from each of 32 greenhouse-grown populations representing the distribution of S. latifolia across Europe. The 316 grains were scored for 11 morphological characters (61 character states) under the light microscope. Population character-state frequencies were analysed using cluster analysis and principal components analysis. The results support the geographic distribution of pollen morphs, but the populations with the typical eastern and western morphs are linked by a belt of populations with intermediate pollen morphology. Intermediate pollen is characteristic of populations in a zone from Belgium to Italy; the zone represents a region of relatively rapid morphological change and is coincident with a similar zone of change in seed and flavonoid characters in S. latifolia. Scanning electron micrographs from each population provided further information on the pollen morphology and complemented the light microscopical observations. The variation pattern is illustrated by scanning electron micrographs from selected populations.