Evaluating morphological diversity among Plantago major L. populations and influence of ecological variables

Invasive plant species are a major threat to biodiversity worldwide. Thus, information on their distribution, morphological variation as well as their reaction to ecological parameters are required to adequately evaluate their threat and manage invasions. Plantago major is a cosmopolitan invasive plant species and a possible threat to the local flora in dry grasslands. A multivariate analysis of data acquired from 19 populations of this species across various locations in Iran was used to evaluate the diversity of quantitative and qualitative morphological traits possibly affected by ecological factors to understand its distribution pattern. Morphological traits were variable and depended on the location of observation. Quantitative traits in particular exhibited a higher variation than qualitative traits between populations, with higher diversity in populations from the Central Alborz and Khorasan. Further, populations with higher vegetative growth had relatively lower reproductive fitness, i.e. a trade-off between the number of seeds per individual and vegetative traits. Cluster analysis based on either morphological data or ecological variables were capable to group the populations close to their geographical origins, despite correlation coefficients of ecological variables with morphological traits being mainly non-significant. Our results provide important insights into the variability of P. major and potentially allow inferences on distribution limits in Iran.