Genome size, morphological and palynological variations, and heterostyly in some species of the genus Linum L. (Linaceae) in Iran

Heterostyly is the occurrence of flowers with different sexual organ arrangements in different plants of the same species. This floral polymorphism occurs in four sections of genus Linum. The present study compares the morphological, palynologycal and genome size (C-value content) characteristics in the long-styled and short-styled plants in three Linum species, that is, Linum austriacum L., Linum album Ky.ex Boiss.and L. glaucum Boiss. & Nöe . 15 qualitative and quantitative morphologicalcharacters from both vegetative and reproductive organs of these plants were studied.A higher mean value of the plant height, size of the basal leaves width, flower leaves width, calyx length, sepal length and petal length occurred in the long-styled plants, while the mean value of branch number, basal leaves length, flower leaves length, calyx width, pedicel length and sepal length was higher in the short-styled plant populations. T-test analysis of morphological characters showed significant difference (p<0.05) for some of the characters studied. Principal coordinate analysis (PCoA) plot of long-styled and short-styled plant populations based on all morphological characters also separated these two kinds of plants in the three species studied. The pollen obtained from the mature buds was prepared for light microscopy (LM) and scanning electron microscopy (SEM). The polar and equatorial views of the pollen grains were similar in the long-styled (Ls) and short-styled (Ss) plants but the aperture shape differed in these populations. C-values obtained by flow cytometry, differed in the long-styled and short- styled plants of the species studied. The analysis of variance (ANOVA) test performed among the three Linum species showed a significant difference in 2C-value content. Positive significant correlation was observed between 2C-value and northern distribution of the Linum species studied, while a negative significant correlation occurred with eastern distribution. Key words: Heterostyly, Linum, morphology, palynology, genome size