The effects of declining plant biodiversity on ecosystem processes are well studied, with most investigations examining the role of species richness declines rather than declines of species abundance. Using grassland mesocosms, we examined how the abundance of a native, resident species, Hemizonia congesta (hayfield tarweed), affected exotic Centaurea solstitialis (yellow starthistle) invasion....

Understanding the role of competition in the organization of communities is limited in part by the difficulty of extrapolating the outcomes of small-scale experiments to how such outcomes might affect the distribution and abundance of species. We modeled the community-level outcomes of competition, using experimentally derived competitive effects and responses between an exotic invasive plant, ...

Our understanding of the potential mechanisms driving the spread and naturalization of alien plant species has increased over the past decades, but specific knowledge on the factors contributing to their increased impact in the introduced range is still urgently needed. The native European plant Centaurea stoebe occurs as two cytotypes with different life histories (monocarpic diploids, allo-po...

The species of Asteraceae have been found to be a rich source of externally accumulated flavonoid aglycones. This type of compounds attracts the attention, besides for their importance as chemotaxonomic markers, also for their ecological role. In the present study, two local endemic species, Centaurea davidovii and C. parilica, and one widespread species from the same group, C. stenolepis, are ...

Specimens of the knapweed nematode Subanguina picridis (Kirjanova) Brzeski obtained from different host plants were highly variable in measurement and structure. This variability refutes the validity of six Subanguina species attacking plants in the Asteraceae.

A taxonomic account of the Centaurea parlatoris complex (Asteraceae), endemic to Sicily, is presented. This includes six taxa, three described in 19th century (C. parlatoris, C. var. tomentosa and virescens) recently sicana, giardinae heywoodiana). Starting from designation types for oldest plant names that have not been typified yet, considerations are formulated virescens elevated rank specie...