Harrington, Judith Eileen, authorBrick, Mark A., advisorBlack, William C., IV, committee memberPanella, Leonard W., committee memberWard, Sarah M., committee member2022-04-202022-04-202010https://hdl.handle.net/10217/234740Covers not scanned.The taxonomic status of the North American endemic grass Distichlis spicata subsp. striata has been in flux for more than a century. Distichlis spicata hosts the larval stage of a federally endangered butterfly and is being investigated for use in restoration and recreation, so the relationship between the species and its subspecies merits clarification. Although the subspecies stricta was once recognized as a species {Distichlis stricta), most current treatments either consider it an inland subspecies within Distichlis spicata or decline to recognize it at all. Two recent studies did not find genetic or morphological evidence differentiating the subspecies stricta from Distichlis spicata. Genetic variation among 13 coastal and inland populations of Distichlis spicata sensu lato was characterized using chromosome counts, chloroplast DNA segments, microsatellite alleles, RAPD bands, and DNA C-values. Plants grown in a common garden were evaluated for date of first flowering. The results suggest the existence of two genetically segregated lineages that differ for chromosome number, molecular sequences in cpDNA and nuclear DNA, DNA C-value, and flowering time. One lineage has a somatic chromosome number of 2n = 40 and encompasses plants from the West Coast and several inland locations in Nevada, Utah, and southern New Mexico. The other lineage has a somatic chromosome number of 2n = 38 and consists of plants distributed only inland among the populations surveyed. Genetic distances among populations were closer within each lineage than between the two lineages, even when different lineages occurred in geographic proximity. The 38-chromosome lineage should be recognized as a distinct species corresponding to the previously recognized Distichlis stricta. The 40- chromosome lineage is Distichlis spicata.doctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Distichlis spicata -- West (U.S.)Grasses -- Variation -- West (U.S.)Text