Insect-mediated indirect interactions between native plant species recently have been shown to be important determinants of plant performance in a number of ecological communities. However, the potential indirect effects of exotic plant invasion on native plant species are not well understood. We examined whether the presence or proximity of the targeted exotic weed, musk thistle, influences th...

Postrelease studies can provide data with which to evaluate expectations based on prerelease tests of biological control insects. In 2004, we observed Trichosirocalus horridus Panzer (Coleoptera: Curculionidae), the rosette weevil introduced into North America against Eurasian thistles, feeding on native tall thistle, Cirsium altissimum L. Spreng., in tallgrass prairie. In this study, we examin...

Postrelease studies can provide data with which to evaluate expectations based on prerelease tests of biological control insects. In 2004, we observed Trichosirocalus horridus Panzer (Coleoptera: Curculionidae), the rosette weevil introduced into North America against Eurasian thistles, feeding on native tall thistle, Cirsium altissimum L. Spreng., in tallgrass prairie. In this study, we examin...

Theory predicts that damage by a shared herbivore to a secondary host plant species may either be higher or lower in the vicinity of a preferred host plant species. To evaluate the importance of ecological factors, such as host plant proximity and density, in determining the direction and strength of such herbivore-mediated indirect effects, we quantified oviposition by the exotic weevil Rhinoc...

Milk thistle (Silybum marianum (L.) Gaertn.) is one of the valuable medicinal plants which used in the treatment of liver disorders. The major active constituents in this plant are flavonolignans, collectively known as silymarin which is a mixture of three isomer silybin, silydianin and silycristin. Its therapeutic properties are due to the presence of silymarin. The seeds contain the highest a...

Insect herbivory is common, but the conditions under which it reduces the fitness and population size of plants remain poorly understood. We quantified populationlevel impacts of floral herbivory by specialized insects on cobweb thistle (Cirsium occidentale var. occidentale) in a California coastal dune ecosystem, and then compared these demographic effects to those published for Platte thistle...

Understanding spatial and temporal variation in factors influencing plant regeneration is critical to predicting plant population growth. We experimentally evaluated seed limitation, insect herbivory, and their interaction in the regeneration and density of tall thistle (Cirsium altissimum) across a topographic ecosystem productivity gradient in tallgrass prairie over two years. On ridges and i...

milk thistle (silybum marianum (l.) gaertn.) is one of the valuable medicinal plants which used in the treatment of liver disorders. the major active constituents in this plant are flavonolignans, collectively known as silymarin which is a mixture of three isomer silybin, silydianin and silycristin. its therapeutic properties are due to the presence of silymarin. the seeds contain the highest a...

background and objectives: milk thistle (silybum marianum), a medicinal plant of the asteraceae family that have been used long time ago, in the treatment of liver disease. sowing date of this plant has not been determined, therefore, this study was necessary. this plant was identified as a weed, this plant is identified as a weed, while silymarin in the seeds are used in the anti-hepatitis and...

Understanding spatial and temporal variation in factors influencing plant regeneration is critical to predicting plant population growth. We experimentally evaluated seed limitation, insect herbivory, and their interaction in the regeneration and density of tall thistle (Cirsium altissimum) across a topographic ecosystem productivity gradient in tallgrass prairie over two years. On ridges and i...