Cytological and Taxonomic Studies in the Genus Brodiaea

Abstract

1. The chromosome numbers of twenty-four species and varieties of Brodiaea have been investigated. 2. Somatic numbers of 10 (11), 12, 14, 16, 18, 28, 28 (30), 32, 36, 42, 48, and 50 chromosomes were observed. An incomplete series of corresponding gametic numbers includes 5 (6), 6, 8, 9, 14, 16, and 21. 3. Taxonomic and cytological findings seem to justify the separation of the material examined into three genera, Brodiaea, Dichelostemma, and Triteleia. It is suggested that the basic number for Brodiaea is 6, and for Dichelostemma the secondarily basic number 9, derived from 6; the variation of numbers in Triteleia is too great to postulate any one basic number. 4. The need for reconsideration of certain specific delimitations is suggested on the basis of cytological and taxonomic observations. 5. Variation of chromosome number is reported for two plants and an explanation for one of the variations offered on the basis of duplication of a chromosome and subsequent dislocation.