The genus crocus (Family – Iridaceae or Iris) contains Ca. 150 small, corm bearing, perennial species distributed C S Europe, N. Asia and W. China. These species are highly valuated as ornamental plants of their colourful flowers, horticultural varieties and industrial application, sub-genus crocus – crocus orientales –series are closely related species; and are difficult to be separated taxonomically and have a complex cytology. Botany, taxonomy and infra-specific of crocus orientales series are presented, and their distribution, ecology, phenology, description and chromosome counts are also provided with key of their identification