The evolution and taxonomy of Calectasia cyanea R. Br. (Xanthorrhoeaceae) in terms of its present-day variation and cytogenetics

Abstract

Calectasia cyanea R. Br. was collected at 48 sites throughout its range in southern South Australia and western Victoria, and in southern and western Western Australia.

The eastern and western populations have been separated since Miocene times by various factors such as the sea, drought, soil conditions, and temperature.

Ecological, morphological, chemical, palynological, and cytological features were studied to determine the variation within the populations. The close similarity of all populations of Calectasia in morphology, chemistry, pollen, and chromosome number indicated a stabilizing mechanism. This mechanism was found to be a cytological aberration of the ninth chromosome, which causes 20-30 % of the genetic material to be inherited as a supergene, thus maintaining a permanent, unchangeable heterozygosity. Two new varieties were recognized.