Phenology and common garden and reciprocal transplant studies of Polymnia canadensis (Asteraceae), a monocarpic species of the North American Temperate Deciduous Forest

Abstract

Polymnia canadensis, an herbaceous plant species ofthe North American Temperate Deciduous Forest heretofore reported as beingperennial, is shown to be primarily monocarpic. In common garden experiments,the majority of plants grown from seeds or seedlings collected in Kentucky,Alabama, Virginia, Ohio, and Missouri were monocarpic, but some were dicarpic,tricarpic or polycarpic. Observations in natural populations of P.canadensis suggested that there is variation in the life history ofthis species throughout its geographic range. Anthesis date and height ofplantsat anthesis were significantly different between mesic and dry field sites incentral Kentucky populations, but common garden and reciprocal transplantexperiments showed that these were due mainly to environmental (and not togenetic) effects. The latter was also true for age of maturity and rate ofchange in plant height. Lack of significant site × source interaction forthese characters indicated that plants did not differ in their plasticresponsesbetween sources at each site. Winter annual, biennial, triennial, and dicarpicand tricarpic perennial life histories occurred within populations in bothcommon garden and reciprocal transplant experiments. In the latter experiments,most matured plants were either biennials (most common) or winter annuals(second most common), with the order reversed in the former experiments due toamore benign environment favoring earlier maturity. The extensive phenotypicplasticity displayed by P. canadensis for phenology andlife history enables the species to inhabit a wide range of environments.