Liatris aspera andL. spicata are remotely related species, and rarely have an opportunity to hybridize because of different flowering periods and ecological tolerances. Seasonal and ecological barriers have been surmounted in a population in southern Cook County, Illinois, which has resulted in extensive hybridization. The population was characterized on the basis of morphological and chemical features, pollen fertility, and chromosome pairing relationships. Plants considered to be F1 hybrids on the basis of morphology typically displayed the phenolic markers of both parental species, reduced fertility, and meiotic irregularities in the form of univalents and translocation figures. Plants judged to be backcrosses toL. aspera contained some of the phenolics ofL. spicata; however, backcrosses toL. spicata invariably lacked the phenolics ofL. aspera. The species-species phenolics ofL. aspera were inherited as a block, i.e., a hybrid had all or none of these compounds. The complex pattern of gene exchange within the population reflects the weakness of crossing and fertility barriers to hybridization.
KeywordsPollen Fertility Corolla Tube Advanced Generation Backcross Hybrid Extensive Hybridization
Unable to display preview. Download preview PDF.
- Alston, R. E. 1964. The genetics of phenolic compounds. Pp. 171–204.In Harborne, J. B. (Editor). Biochemistry of Phenolic Compounds. London & New York: Academic Press.Google Scholar
- Bateman, A. J. 1951. The taxonomic discrimination of bees. Heredity5: 271–278.Google Scholar
- Cruise, J. E. 1964. Biosystematic studies of three species in the genusLiatris. Canadian Jour. Bot.42: 1445–1455.Google Scholar
- Gaiser, L. O. 1946. The genusLiatris. Rhodora48: 165–183, 216–263, 273–326, 331–382, 393–412.Google Scholar
- — 1963. The Origin of Adaptations. New York: Columbia Univ. Press. x + 606 pp.Google Scholar
- — 1964. The Architecture of the Germplasm. New York: John Wiley & Sons, xv + 236 pp.Google Scholar
- Hadley, E. B. & D. A. Levin. 1967. Ecological regulation of hybridization in a complexLiatris population. Amer. Jour. Bot.54: (in press).Google Scholar