Environmental influence on interspecific and intraspecific variation within the genus Osmorhiza in northern Michigan.

Closely related species are often hard to differentiate between, with only subtle differences as keys to look for. One genus of plant, Osmorhiza, has four species native to Michigan, two of which are nearly identical except for two inconspicuous traits. We gathered measurements of 109 Osmorhiza plants, including the three more common species, and took soil measurements of pH and percent moisture with the objective of finding if interspecific variation is greater than intraspecific variation and what role abiotic environmental factors play in shaping the species' morphological characteristics. We randomly chose Osmorhiza plants dispersed throughout the Headlands, an Emmet County park, as we hiked its northern trails. On each plant we measured pubescence (on leaf, petiole, umbel, and stem), bract and style length, scent, and presence of purple coloration. When these values were compared against the soil variable, we found that every trait measured showed more variation between the species than within the individual species. We also found that the environmental factors are significant in explaining the growth location of all three species. We conclude that, while the species lineation and defining characteristics can be controversial, no evidence has yet offered a more thorough explanation for the evolutionary history of Osmorhiza.http://deepblue.lib.umich.edu/bitstream/2027.42/55073/1/3518.pdfDescription of 3518.pdf : Access restricted to on-site users at the U-M Biological Station