Cytological studies in South AmericanIridaceae

Although the South AmericanIridaceae are cytologically diverse, three tribes are distinguishable on the basis of karyotype morphology. TheSisyrinchieae andTrimezieae have variable basic numbers, ploidy levels and chromosome sizes, while theTigridieae are characterized by a relatively uniform basic number and bimodal karyotype. Changes in chromosome size within genera may suggest fluctuations in their DNA amount with latitude and altitude, particularly inSisyrinchium. The results are considered in terms of opportunities for more detailed research.