Search

An attempt was made to relate variation in life-history characteristics within a population of Plantago major ssp. pleiosperma to small-scale environmental variability. At a beach plain, embanked in 1966, a mosaic environment was distinguished with spatial variability in vegetation structure as well as in nutrient availability and water content of the soil. Differences between three subsites in contemporary selection were demonstrated, e.g. in shoot morphology and allocation to reproductive tissue. The effects of nutrient supply and waterlogging on morphology and life history were studied on lines from the three subsites in a greenhouse. For most of the traits high levels of phenotypic plasticity were observed, covering almost entirely the observed phenotypic variability at the beach plain. In all treatments lines from the shrubs had, however, a higher leaf-area ratio as well as delayed flowering when compared to lines from more open subsites. In addition, in a reciprocal transplant experiment it was demonstrated that lines from the shrubs had larger shoots with e.g. broader leaves in the shady environment of the shrubs than other lines. From the experiments no indications were obtained that lines from any subsite were especially adapted to specific levels of nutrient supply or water content of the soil. With respect to these environmental factors P. major ssp. pleisoperma might occur and reproduce at all subsites by means of phenotypic plasticity, e.g. in plant form. However, it is suggested that spatial variability in vegetation structure caused a population subdivision in allocation patterns, leaf form and life history at the beach plain, over distances of about 15-25 m. This differentation occurred during primary succession over a period of twenty years.

Plantago maritima L. is a halophytic species occurring on beach plains, mud flats, salt marshes, sea dikes, coastal grasslands and sea cliffs. A great variety in morphological characteristics can be found; based on differences in leaf characters, Heukels (1910) distinguished three types.

Survival, age and size at first flowering and seed production of five populations of Plantago major were studied in a reciprocal-transplant experiment to investigate if differences in flowering phenology can be explained by different selection regimes. Survival in the pre-reproductive phase was relatively low on a river bank, a beach plain and a path, compared to that in a sea-shore meadow and a dune grassland. Age at first flowering depended on the site as well as on the population from which plants originated (...)