Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10(-5) M; synthetic maculosin possessed chemical and biological activities identical to those of the n...

Centaurea cineraria L. (Compositae: Cardueae: Centaureinae), part of the group, is described and illustrated, notes provided on its cultivation, propagation, pests diseases availability. Within current concepts full synonymy C. gymnocapra are along with type citations known distribution material. The infrageneric divisions commented briefly. varying treatments complex species discussed, some cl...

The response of plant species to future atmospheric carbon dioxide concentrations [CO(2)] has been determined for hundreds of crop and tree species. However, no data are currently available regarding the response of invasive weedy species to past or future atmospheric [CO(2)]. In the current study, the growth of six species which are widely recognized as among the most invasive weeds in the con...