Genome Size Variation in Sisyrinchium L. (Iridaceae) and Its Relationship to Phenotype and Habitat

Genome size was measured in 62 plants belonging to 36 known and three unknown species of Sisyrinchium from a wide geographical range in the American continents, between British Columbia and Tierra del Fuego. Genome size varied up to 7.7-fold among species. In the Northern Hemisphere, genomes were uniformly small and varied between two and 12 in number. In the Southern Hemisphere, two groups were identified; species with x = 9 were predominantly diploid and showed an increase in genome size with latitude. Those with x = 8 had small genomes and varied in genome number, as in Northern Hemisphere species. The increase in genome size among diploid species in the Southern Hemisphere showed a positive correlation with seed weight but was not correlated with epidermal cell volume. Variation in genome size is suggested to be related to onset of growth, length of growing period, and reproductive strategies.