Experimental Ecological Genetics in Plantago Iv. Effects of Temperature on Growth Rates and Reproduction in Three Populations of Plantago Lanceolata L. (Plantaginaceae)

The effects of temperature on growth rates and flowering responses of Plantago lanceolata L. populations sampled from open, shaded, and sunflecked habitats were studied in controlled environments. A large number of characteristics were phenotypically plastic in response to a broad range of temperatures. Low night temperatures substantially reduced reproductive effort, whereas high temperatures produced a reduction in total biomass. Temperature had little effect on leaf or inflorescence production rates, other than at very low temperatures. The phenotypic plasticity observed in the growth chamber correlated well with the observed seasonal phenology. Genetic differences were found in inflorescence height and total plant productivity. The rapid growth rate, the high reproductive effort, and generally broad temperature optimum to moderate temperatures are consistent with the occurrence of P. lanceolata in a wide variety of disturbed habitats in temperate latitudes.