Phylogeographic relationships within Packera sanguisorboides (Asteraceae), a narrow endemic species that straddles a major biogeographic boundary.

Packera sanguisorboides is endemic to the Sangre de Cristo and Sacramento Mountains of New Mexico, USA. As such, its distribution spans the boundary between two major floristic regions: the southern Rocky Mountain region and the Madrean region. Chloroplast DNA haplotype polymorphism patterns in populations from both regions show that most of the molecular variance exists among populations rather than between mountain ranges and that hybridization with at least one other Packera species containing distinct cpDNA haplotypes has contributed to the cpDNA diversity within P.

Stable oxygen and hydrogen isotope composition of leaf water in C and C plant species under field conditions.

In this paper we make comparisons between the observed oxygen and hydrogen stable isotope composition of leaf water and the predictions of the Craig-Gordon model of evaporative isotopic enrichment. Comparisons were made among two C species (Chenopodium album and Helianthus annuus) and two C species (Amaranthus retroflexus and Kochia scoparia), when plants were exposed to natural environmental conditions in the field. There were significant differences among the species for the hydrogen and oxygen isotopic composition of leaf water at mid-day.