Yellow starthistle (Centaurea solstitialis L.) is a summer-flowering annual plant of the family Asteraceae, and a significant weed of roadsides, pasture and grasslands in California. It is also distributed, though with less economic and ecological significance, throughout the US and in other temperate parts of the world. Yellow starthistle grows vigorously during the dormant period for most nat...

The insect Rhinocyllus conicus Froehlich is a flowerhead weevil deliberately introduced into the United States for the biological control of invasive exotic thistles in the genus Carduus. This study documents the course and magnitude of the weevil population expansion onto nontarget host plants. No weevils were reared from either Platte thistle, Cirsium canescens Nuttall, or wavyleaf thistle, C...

In this study, the micromorphology of vegetative and reproductive structures endemic Centaurea glaberrima Tausch subsp. divergens (Vis.) Hayek (Asteraceae), using scanning electron microscope (SEM), is presented for first time. Uniseriate whip-like non-glandular biseriate glandular trichomes are found on surface all aboveground parts (stem, leaves, peduncles, involucral bract). On adaxial leaf ...

We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in the galaxy NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499 to 678 days after outburst and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer models show that up to 0.02 solar masses of dus...